3rd International Whitefly

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Symposium 2018 Putting Farmers First Esplanade Hotel Fremantle byrd Rydges, Western Australia

3 Internatio 16 – 19 September 2018

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Program Book IWS 2018 Program Book A4 24pp PR.indd 1

12/9/18 2:35 pm

Welcome to Perth! Dear Colleagues, Welcome to beautiful Perth, Western Australia. It is my great pleasure, on behalf of the organising committee, to welcome you to the 3rd International Whitefly Symposium (IWS). The Symposium is a merger with the International Bemisia Workshop (IBWS) and the European Whitefly Symposium (EWS) in 2013. The 1st IWS merged Symposium (IWS1) was held 20 – 23 May 2013 on Crete, Greece and the 2nd IWS was held in Arusha, Tanzania from 14-19 February 2016. We are very proud to host the 3rd IWS in Perth and look forward to the exciting program over the 3 days 16 – 19 September 2018. We have over 50 participants from 16 countries. The theme for IWS3 is “Putting Farmers First”. Session topics will include, genomes, systematics and evolution, biology, ecology and invasion biology, whitefly endosymbionts, whiteflyvirus interactions, whitefly-plant interactions, and management and IPM. One of the missions of IWS3 is to increase diversity and inclusion in the whitefly science community. The organising committee is especially proud to welcome the MSc and PhD students from around the world who are the next generation of scientists working on this problem.

The Organising Committee for IWS 2018 extends its appreciation to the following Symposium Sponsors and Supporters for their invaluable commitment and support:

We would like to thank our sponsors The University of Western Australia, Pawsey Supercomputing Centre, and Cray Supercomputers. In addition, thank you to our Symposium supporters CSIRO and the Perth Convention Bureau. I would personally like to thank the organising committee – Dr. Peter Sseruwagi, Dr. Renate Krause-Sakate, and Dr. Sarina Macfadyen – for the hours on skype and the hundreds of emails exchanged to make the event a success. Also, thank you to Lauren Detez and Kellee Butterworth for managing the event. In addition, a huge thank you to all of you who have traveled many hundreds of kilometers and hours to get here to one of the most isolated cities in the world. Enjoy the Symposium and look forward to seeing you at IWS4. Warmest regards, Laura Boykin Chairperson, 3rd International Whitefly Symposium

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IWS 2018 Symposium Managers 3/110 Mounts Bay Road, Perth, WA, 6000 Ph: +61 8 9486 2000 Email: [email protected] Website: www.iws2018.org

IWS Organising Committee

Symposium Supporters

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Laura Boykin

University of Western Australia

Sarina Macfadyen

CSIRO

Renate Krause-Sakate

Universidade Estadual Paulista

Peter Sseruwagi

Mikocheni Agricultural Research Institute

3rd International Whitefly Symposium 2018 iws2018.org

IWS 2018 Program Book A4 24pp PR.indd 2

12/9/18 2:35 pm

Symposium Code of Conduct We are dedicated to providing a harassment-free Symposium experience for everyone, regardless of gender, gender identity and expression, age, sexual orientation, disability, physical appearance, body size, race, ethnicity, religion (or lack thereof), or technology choices. We will not tolerate harassment of Symposium participants in any form. Sexual language and imagery is not appropriate for any Symposium venue, including talks, parties, Twitter and other online media. Symposium participants violating these rules may be sanctioned or expelled from the Symposium without a refund at the discretion of the Symposium organisers. Harassment includes offensive verbal comments related to gender, gender identity and expression, age, sexual orientation, disability, physical appearance, body size, race, ethnicity, religion, technology choices, sexual images in public spaces, deliberate intimidation, stalking, following, harassing photography or recording, sustained disruption of talks or other events, inappropriate physical contact, and unwelcome sexual attention. Participants asked to stop any harassing behaviour are expected to comply immediately. Sponsors are also subject to the anti-harassment policy. In particular, sponsors should not use sexualised images, activities, or other material. Booth staff (including volunteers) should not use sexualised clothing/uniforms/costumes, or otherwise create a sexualised environment. If a participant engages in harassing behaviour, the Symposium organisers may take any action they deem appropriate, including warning the offender or expulsion from the Symposium with no refund. If you are being harassed, notice that someone else is being harassed, or have any other concerns, please contact a member of Symposium

organisers immediately. Symposium organisers can be identified as they’ll be wearing branded clothing and/or badges. You can also send us an email, contact us via our social media platforms, or use this Symposium staff will be happy to help participants contact local law enforcement, provide escorts, or otherwise assist those experiencing harassment to feel safe for the duration of the Symposium. We value your attendance and aim to provide a safe and enjoyable experience for all participants. We expect participants to follow these rules at the Symposium and at any Symposium-related social events.

Contact information Project Manager, Kellee Butterworth 0438 890 283 Emergency number: 000 Original source and credit: Symposium Code of Conduct

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Keynote Speakers In Order of Presentation Dorothy Mukhebi serves as Deputy Director providing the strategic leadership necessary to achieving AWARD’s mission of building a more gender responsive agricultural innovation system. She has 38 years’ experience working with African agricultural networks. Before AWARD, she worked as Coordinator of the Regional Agricultural Information Network (RAIN) of the Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA). She started her career as a Planning Officer with the Kenyan Ministry of Agriculture, and later served for 10 years as a Program Manager with the African, Caribbean and Pacific / European Union (ACP/EU) Technical Centre for Agricultural and Rural Cooperation (CTA), based in Wageningen, the Netherlands. She has also previously worked with the International Centre for Insect Physiology and Ecology (ICIPE), Nairobi, Kenya. Dorothy holds a masters in Information Sciences from Loughborough University of Technology, U.K., and a bachelors in Agriculture from the University of Nairobi. Her hobbies include reading, travelling, photography and jogging. Peter Sseruwagi is a Vector Entomologist, with a PhD from the University of the Witwatersrand, South Africa he obtained in 2005. He is currently working in the Department of Biotechnology, Mikocheni Agricultural Research Institute (MARI), Dar es Salaam, Tanzania, as the Technical Assistant Coordinator for the ‘Disease diagnostics for sustainable cassava productivity in Africa’ project, which aims to build human and infrastructural capacities of seven African NARS in east, central and southern Africa to monitor, diagnose and control whiteflies and whitefly-transmitted viruses (WTV) on cassava. He joined MARI in 2011 as a Senior Investigator/ Postdoctoral Researcher on a Basic Research to Enable Agricultural Development (BREAD) Project coordinated by North Carolina State University (NCSU) to investigate the transmission of Sequences enhancing geminivirus symptoms (SEGS) by cassava whiteflies. Prior to that, he worked as Senior Scientist (Plant Virology/Entomology) and Head of Horticulture Research Programme at the National Crops Resources Research Institute (NaCRRI), Uganda, and as Consultant and Research Associate in the International Institute of Tropical Agriculture-Uganda (IITA-Uganda). His main research goal is to understand and control whitefly and WTV viruses on cassava, sweetpotato and vegetable crops in sub-Saharan Africa, and he has 24 years’ research experience in: whitefly biology, ecology, vector-virus-plant interactions, molecular characterization, pest and disease crop resistance assessment, field epidemiology, surveillance methodology and IPM. He is a reviewer for 15 leading science journals and has authored over 36 ISI scientific papers in peer-reviewed journals, and at least 52 conference presentations. He has wide collaboration within Africa and internationally. Murad Ghanim is a senior scientist at the Volcani Center in Israel and adjunct professor of Entomology in the Hebrew University of Jerusalem, Israel. He graduated from the Hebrew University of Jerusalem focusing his research on the molecular interactions between whiteflies and begomoviruses. He completed a three-year postdoc at Yale University School of Medicine in the USA, and focused his research during this period on Drosophila melanogaster genomics and early embryonic development, after which he joined the Department of Entomology of the Volcani Center in Israel. His research focuses now on the interactions between

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insect vectors of plant pathogens including whiteflies and psyllids with plant pathogenic viruses and bacteria, and factors inside insect vectors that influence pathogen transmission, such as insect proteins and endosymbiotic bacteria. He has published more than 110 ISI papers in peer-reviewed journals. Renate Krause Sakate is adjunct professor of Plant Viruses at São Paulo State University (Unesp), School of Agriculture in Botucatu, Brazil. She graduated in the Federal University of Viçosa, Brazil with a doctorate sandwich period at INRA, Bordeaux, France focusing her research on plant viruses. Her research focuses now on Bemisia tabaci diversity in Brazil and interaction of B. tabaci cryptic species with different plant virus including begomovirus, carlavirus and crinivirus. Manisha Mishra is an INSPIRE scientist at the CSIR-Indian Institute of Toxicology Research, Lucknow, India. She graduated in the year 2016 from the CSIR- National Botanical Research Institute in biological sciences focusing her research on effective control of Bemisia tabaci via strategically identified biomolecules. Her current research interests include the exploration of the molecular mechanism of novel antiwhitefly proteins and impact of transgenic cotton expressing these proteins on whitefly and associated viral diseases. Dr. Mishra is also keen to demonstrate the successful control of whiteflies through RNA interference using unique and Bemisia specific targets. She has published more than 15 ISI papers in peer-reviewed journals with more than 80 impact factor. Everlyne Wosula is a Vector Entomologist at the International Institute of Tropical Agriculture (IITA) Eastern Africa Hub, Dar es Salaam, Tanzania. She joined IITA in 2015 and her research work is focused on cassava-colonizing Bemisia tabaci whiteflies, vectors of viruses that cause devastating cassava mosaic and brown streak diseases in Africa. She is involved in molecular characterisation, studying the feeding behaviour and virus transmission characteristics, and exploring novel techniques for management of the whiteflies. Prior to joining IITA, she worked as a Postdoctoral Research Associate (2013 – 2015) in the Department of Entomology at the University of Nebraska-Lincoln. Her research work focused on understanding vector dynamics and virus epidemiology of wheat curl mite-transmitted viruses in wheat. She got a PhD in Plant Pathology (2012) from Louisiana State University. Her dissertation research was on the dynamics of sweet potato viruses and their aphid vectors. Navneet Kaur is an Indian born US Scientist pursuing research in genomics of the whitefly, Bemisia tabaci. Dr. Kaur moved to the US in 2004 after finishing her Master’s degree at Punjab Agricultural University in Ludhiana, India. She received a PhD in molecular biology and biotechnology from the University of Arkansas, Fayetteville in 2009. She has been studying whitefly genomics for the past four years with the USDA-ARS in Salinas, CA. Dr. Kaur is curious to understand the influence of plant viruses on the whitefly vectors that transmit them, particularly with the semipersistently transmitted Criniviruses that inflicts serious damage to agriculture crops worldwide, such as tomato and melon. In addition to implementing high-throughput genomics techniques to study vector – virus interactions, Dr. Kaur is also developing RNAi-based strategies for sustainable control of whitefly in food crops.



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IWS 2018 Program

Program updated 05/09/2018

Sunday 16 September 2018 16:00

18:30

Registration Open Marine Lounge Bar

17:30

18:30

Welcome Drinks

Monday 17 September 2018 8:00

16:30

Registration Open Sirius Room

8:30

8:35

Symposium Welcome Laura Boykin

8:35

8:50

Official Symposium Opening Ceremony Professor Peter Klinken – Chief Scientist

8:50

9:35

Engendering a Diversity Lens to Improve Agriculture Prosperity – lessons from AWARD Dorothy Mukhebi, Keynote Speaker

9:35

11:20

Biology, Ecology and Invasion Biology – Chairperson – Marie Connett Sirius Room

9:35

10:20

Why it is critical to understand the biology and ecology of Bemisia tabaci in smallholder farming systems Peter Sseruwagi, Keynote Speaker

10:20

10:35

What has changed in the outbreaking populations of the severe crop pest whitefly species on cassava in two decades? Hadija Ally

10:35

10:50

Ecological considerations for designing research questions and sampling plans to investigate the Bemisia tabaci species complex Alana Jacobson

10:50

11:05

Silver leaf whitefly predation: a DNA approach to its evaluation Tanya Smith

11:05

11:35

Morning Tea

11:35

12:20

Biology, Ecology and Invasion Biology – Chairperson – Patrick Chikoti Sirius Room

11:35

11:50

African Cassava Genotypes Expressing Whitefly Resistance Catherine Gwandu

11:50

12:05

Early embryonic development in Bemisia tabaci Rebecca Corkill

12:05

12:20

Characterization of genes encoding small heat shock proteins from Bemisia tabaci and expression under thermal stress Jing Bai

12:20

12:30

IWS3 Group Photo

12:30

13:30

Lunch

13:30

14:30

Whitefly Virus interactions 1 – Chairperson – Hélène Delatte Sirius Room

13:30

13:45

Proteomic analysis of the interactions between TYLCV CP and its vector proteins reveals the role of Tid in constraining viral retention Jing Zhao

13:45

14:00

Whitefly transmission, host range, and cloning of a Datura isolate of the torradovirus, tomato necrotic dwarf virus William Wintermantel

14:00

14:15

Comparison of transovarial transmission of Tomato yellow leaf curl virus by seven cryptic species of the Bemisia tabaci whitefly complex indigenous to China Qi Guo

14:15

14:30

Performance of Bemisia tabaci MEAM1 and Trialeurodes vaporariorum on healthy and Tomato chlorosis virus infected tomato plants and efficiency of virus transmission Renate Krause-Sakate

14:30

15:30

Poster Session – Chairpeople – Ibrahim Umar Mohammed and Peter Sseruwagi

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IWS 2018 Program Tuesday 18 September 8:00

16:30


8:30

10:00

Whitefly Virus interactions 1 – Chairperson- Dorothy Mukhebi

8:30

9:15

Changing a paradigm in plant virus transmission: an aphid-borne polerovirus switches its vector to the whitefly Bemisia tabaci Murad Ghanim, Keynote Speaker

9:15

9:30

The whitefly transmitted Cowpea mild mottle virus can be an important component to reduce productivity of soybean in Brazil Renate Krause-Sakate

9:30

9:45

Real time portable genome sequencing for global food security Laura Boykin

9:45

10:00

Unusual occurrence of a DAG motif in the Ipomovirus Cassava brown streak virus Monica Kehoe

10:00

10:30

Morning Tea

10:30

12:30

Whitefly Plant Interactions – Chairperson – Tonny Kinene Sirius Room

10:30

11:15

Panoramic situation of whiteflies in Brazil and the efficiency of the different cryptic species to transmit viruses Renate Krause-Sakate, Keynote Speaker

11:15

11:30

Influence of plant-produced volatile chemicals towards host-selection behaviour of the cassava whitefly B. tabaci Latifa Mrisho

11:30

11:45

Nymph mortality – a potent mechanism of whitefly resistance in Medicago sativa L. (alfalfa) Linda Walling

11:45

12:00

Indirect whitefly/plant interactions: honeydew related factors affecting cotton lint quality and options for mitigation Simone Heimoana

12:00

12:15

Evaluation of whitefly parasitism on weeds, cassava and other crops in the field Yolice Tembo

12:15

13:15

Lunch Sirius Room

13:15

14:30

Management, Control and IPM 1 – Chairperson Alana Jacobson

13:25

13:30

Enhancing Watermelon with Resistance against Whiteflies Alvin Simmons

13:30

13:45

Biological Control Informed Thresholds for Enhancing IPM of Whiteflies in Cotton Peter Ellsworth

13:45

14:00

Implementing an IPM program for Silverleaf whitefly in vegetable crops Siva Subramaniam

14:00

14:15

Audacious Insect Control Approaches for an Impatient Optimist Marie Connett

14:15

14:30

Management of Cowpea mild mottle virus and the whitefly vector in beans Peter Nimmo

14:30

15:00

Short Break Sirius Room

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15:00

16:30

Management, Control and IPM 2 – Chairperson Jing Bai

15:00

15:45

Expression of an insecticidal fern protein in cotton protects against whitefly Manisha Mishra, Keynote Speaker

15:45

16:00

Bemisia tabaci insecticide resistance management in Australian cotton Jamie Hopkinson

16:00

16:15

Field evaluation of synergists to overcome pyrethroid resistance in silverleaf whitefly Siva Subramaniam

16:15

16:30

Knockdown of gut dsRNAses to improve feeding RNAi efficiency of osmoregulatory genes in B.tabaci Mridula Gupta



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Wednesday 19 September 8:00

16:00


8:30

9:15

SNP-genotyping using NextRAD sequencing unravels the genetic diversity of cassava-colonizing Bemisia tabaci Everlyne Wosula, Keynote Speaker

9:15

10:00

Systematics and Evolution – Chairperson Yolice Tembo Sirius Room

9:15

9:30

Quality control of molecular data for defining Bemisia tabaci cryptic species status Wee Tek Tay

9:30

9:45

Patterns of conflict between nuclear and mitochondrial cytochrome oxidase I (mtCOI) DNA phylogenies in Bemisia tabaci species complex Tonny Kinene

9:45

10:00

Genetic diversity of mitochondrial DNA of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) associated with cassava and occurrence of cassava mosaic disease in Zambia Patrick Chikoti

10:00

10:30

Morning Tea

10:30

12:30

Genomes- Chairperson – Chairperson Denis Persley Sirius Room

10:30

11:15

Common and distinct gene expression changes in whitefly (Bemisia tabaci, MEAM1) after feeding on three virus-host plant combinations, and whitefly control through RNAi Navneet Kaur, Keynote Speaker

11:15

11:30

CRISR/Cas9-mediated Genome Editing in the Whitefly, Bemisia tabaci Peter Atkinson

11:30

11:45

Genome-wide profiles of miRNAs and piRNAs in whitefly Bemisia tabaci in response to feeding on tomato plants infected with Tomato yellow leaf curl virus Kai-Shu Ling

11:45

12:00

Silencing of Vitellogenin Gene In Bemisia tabaci (Gennadius) Inhibits Fecundity And Egg Hatching Vikas Jindal

12:00

12:15

Optimum field sampling of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations: A management decision tool Peter Sseruwagi

12:15

12:30

NURU, an artificial intelligence system for diagnosis of plant diseases and pests Latifa Mrisho

12:30

13:30

Lunch

13:30

15:30

Management, Control and IPM 3 – Chairperson Vikas Jindal Sirius Room

13:30

13:45

Using simulation modelling to inform best management practice for the introduction of whitefly-resistant Cassava varieties Hazel Parry

13:45

14:00

An overview of Bemisia tabaci (Gennadius) MEAM1 (silverleaf whitefly) management in Australian cotton: past, present and future Richard Sequeira

14:00

14:15

Managing Whitefly, Bemisia tabaci Through Implementation of Integrated Pest Management In Indian Punjab Vijay Kumar

14:15

14:30

Automated whitefly counting – an evaluation of 3 methods Solomon Nsumba

14:30

14:45

Resistance to insecticides of MEAM1 and IO whitefly species (Hemiptera: Aleyrodidae) in La Réunion Alizee Taquet

14:45

15:00

Threats to vegetable production from whitefly-transmitted viruses in the southeastern United States: Insights into whitefly-virus interactions and epidemics Rajagopalbabu Srinivasan

15:00

15:30

Closing Ceremony IWS4 Location

19:00

23:00

Symposium Dinner

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Oral Abstracts Engendering a Diversity Lens to Improve Agriculture Prosperity – lessons from AWARD Author: Dorothy Mukhebi There is a plethora of scholarly literature that has underscored the significant role of women in agriculture in sub-Saharan Africa. It has also been widely recognized that agriculture-driven prosperity can only be achieved if inclusiveness and diversity in agricultural development is embraced. To achieve this, it is fundamental to acknowledge that diversity in the farming sector is not just a ‘women’s issue’. Women are not only a heterogenous group of actors, but they also act alongside other players in agricultural development. It is imperative that all actors along the agricultural value chains are engaged appropriately. A holistic diversity and inclusion approach to addressing gender inequality in agriculture, would see a much-needed increase in global food security. African Women in Agricultural Research and Development (AWARD) was established under the premise of data that showed that while women are a vital force in Africa’s agriculture, they are disproportionately represented. For example, only one in four agricultural researchers are women and even fewer – one in seven – of the leadership positions in African agricultural research institutions are held by women. Through its Fellowship, AWARD has invested in the continent’s leading women agricultural scientists to ensure a growing cohort of capable, confident, and influential African women scientists available to lead critical advances and innovations for the agricultural sector. The women who participate in this career development program tackle some of the most intractable problems facing farmers. To evaluate the fellowship’s impact on empowerment of women in agricultural research and development, AWARD developed the African Women in Science Empowerment Model (AWSEM) tool. The work has produced data and lessons that informs the impact of empowering African women in science. While investment and implementation of interventions tailored specifically for women is crucial for gender equity, it is certainly not sufficient to tackle the inefficiencies facing the agricultural sector across and beyond Africa. Recently, AWARD has expanded its mandate to invest in both men and women in the agricultural research and development ARD sector. We are now working toward inclusive, agriculture-driven prosperity for Africa by strengthening the production and dissemination of more inclusive and gender responsive agricultural research and innovation (GRARD). It has been recognized that, some ARD initiatives pay too much attention to the face value of, for example, women’s roles in agriculture and women’s lack of access to resources. In so doing, they fail to consider the underlying socio-cultural factors and unseen causes of inequality that have created, and maintain, the gender gap in Africa’s agriculture. Therefore, it is not adequate to focus on interventions that solely focus on women. It is imperative to dig deeper to find what the specific gender and social issues are at hand before planning an intervention.

Why it is critical to understand the biology and ecology of Bemisia tabaci in smallholder farming systems Author: Peter Sseruwagi Co-authors: Sarina Macfadyen, Laura Boykin, Luis Canas Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a frequent and severe pest in Sub-Saharan Africa, yet there remains limited understanding by scientists and farmers of the biology and ecology of whiteflies in smallholder farming systems. This is despite the large amount (hundreds of scientific papers per year) of information generated on the pest by scientists and private companies dealing in pest management products and services. Bemisia tabaci exhibits a high level of diversity, with a short reproduction cycle that quickly builds up large populations. It is adapted to many plant hosts

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(polyphagous), ecologies, and climatic conditions. Management of B. tabaci is complicated by the complex ecology that defines smallholder farming. Smallholder farmers lack science-based information on the biology and ecology of whiteflies in an IPM context. Current management options continue to fail, and millions remain food insecure. Meanwhile, whitefly and whitefly-transmitted viruses (WTV) continue to reduce crop yield and food (leaves, fruits and tuber) quality due to lack of management targeted to smallholder farmers. Building on the knowledge base of stakeholders, including scientists, farmers, extension agents and agro-dealers in whitefly biology and ecology, is key to the sustainable management of the pest. In this talk, I discuss how the current knowledge could be used to design and apply IPM strategies that are effective, affordable, and sustainable for whitefly management in smallholder farming systems. In addition, I will also highlight research gaps that remain to be addressed.

What has changed in the outbreaking populations of the severe crop pest whitefly species on cassava in two decades? Author: Hadija Ally Co-authors: Hajar El Hamss, Christophe Simiand, MN Maruthi, John Colvin, Christopher Omongo, Helene Delatte A Superabundant outbreaking population of the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) species have been associated with epidemics of two viral diseases; cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) in parts of eastern Africa since the early 1990s. We investigated what has changed over two decades in terms of insect population dynamics and genetic patterns using whitefly samples collected on cassava in 1997 during the first whitefly upsurges in Uganda and compared them to more recent collections in 2017. We obtained sequences of the taxonomic barcoding region of the mitochondrial cytochrome oxidase I (mtCOI) and 13 microsatellites loci nuclear markers for a total of 662 samples to study spatial and temporal changes on whitefly evolution and population structures over time. The mtCOI sequences revealed the presence of three B. tabaci species; sub-Saharan Africa 1 sub-group 1 (SSA1-SG1), SSA1 – SG2 and SSA2, and one population of B. afer in 1997, while SSA2 was not found in 2017. SSA1-SG1 dominated in both sampled years, but SSA1-SG2 has increased substantially from being in low abundance in 1997 (n = 2), to much higher numbers in 2017 (n = 122). Bayesian analysis, PCA and genetic diversity indices confirmed the presence of gene flow between the two sub groups -SG1 and -SG2, confirming that they should not be any more considered as separate species. Populations within SSA1 were found structured into 3 genetic clusters, where one genetic cluster dominated in 1997 and two others emerged predominantly by 2017. Contrary to previous suggestions, we did not find any new invading populations associated with the epidemics of CMD, and instead confirmed the presence of two interbreeding populations whose dynamics have changed over time.

Ecological considerations for designing research questions and sampling plans to investigate the Bemisia tabaci species complex. Author: Alana Jacobson The genetic diversity, phylogenetic relationships, and phylogeographic origins of putative species in the Bemisia tabaci species complex continue to be the focus of many studies worldwide. Importantly however, the extent of biological, ecological, and phenotypic variation among genetic groups remains poorly understood. Species- and population-level genetic structuring are important factors underlying observed phenotypic variation in economically important traits including host plant preferences, insecticide resistance, vector competence, and endosymbiont profiles. Linking phenotypic and genetic variation is essential to advancing understanding of the adaptive significance of genetic variation, impacts on species abundance and distribution, interactions with other species, pest status, and competency to transmit and spread plant viruses. An ecological perspective on cryptic species occurring in sympatry will be given using examples from other cryptic species groups. Research to understand phenotypic variation among groups in



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an ecological context so that it can be related to population processes and roles as pests and vectors in epidemiology of plant viruses, requires that sampling plans that are biologically and ecologically relevant to research questions being investigated. The importance of designing and documenting sampling efforts will be discussed.

Silver leaf whitefly predation: a DNA approach to its evaluation Author: Tanya Smith In the 1990s Silver leaf whitefly (SLW) Bemisia tabaci MEAM1 biotype appeared in Australia. As it spread to become a problem pest in cotton, difficulties in controlling it became apparent amongst growers. From previous work with predators of other cotton pests, predation was recognised as an important consideration in moderating pest populations, yet little was known about SLW predators and their ecology in Australian conditions. To identify some of the important predators of SLW, primers were developed to test gut contents of predators commonly found in cotton crops for presence of SLW DNA. Initial testing was done with commonly occurring arthropods to address any cross reactivity, assure that there were no contamination problems and to ascertain that the primer detected SLW DNA. From predators collected from SLW infested cotton, six species were selected for testing: Apple dimpling bug Campylomma liebknechti (Girault), Brown smudge bug Deraeocoris signatus (Distant), Red and blue beetle Dicranolaius bellulus (Guerin-Meneville), Mite eating ladybeetle Stethorus sp., Pale night stalker spider Cheiracanthium mordax (L. Koch) and Lynx spider Oxyopes sp. Feeding starved predators one SLW in a lab situation resulted in primer detection levels unquestionably lower than for field preserved samples. Further experiments showed that up to four SLW needed to be consumed at one time, depending on the species of predator, to allow primer based detection. We further concluded that the primer needs refinement for future experiments to increase sensitivity to Bemisia tabaci MEAM1 and maintain no cross reactivity to Bemisia tabaci AUS1 as well as other common arthropods. The project increased knowledge of the range of arthropods that prey on SLW, identified efficient predators of SLW, provided quantitative data about consumption levels for some predators, and improved the recognition of predation remains specific to certain predators. This information highlights the importance of predation in the control of SLW, which is critical for growers and consultants to make better Integrated Pest Management decisions.

Field parasitism of the cassava whitefly (Bemisia tabaci) by parasitoid natural enemies in Uganda Author: Patrick Ocitti Co-authors: Tom Omara, Sam Morris Opio, Sam Wamani, Alexandrina Acipa, Allan Tek-Kara, Micheal Otim, Andrew Kalyebi, Christopher Omongo The cassava whitefly, Bemisia tabaci causes physical damage to cassava by inducing leaf chlorosis, abscission and sooty mould formation and thus inflicting significant yield losses of about 50%. To date, no appropriate and effective control measures have been developed. While there is research to understand host plant resistance, no parallel efforts have been explored to test the potential of parasitoid natural enemies towards the control of this pest. This study was therefore conducted to assess the impact of parasitoids on the mortality of B. tabaci in cassava; The experiments were conducted during calendar year of 2015, in three different agro-ecologies of Uganda, namely, North-western Savannah Grassland, Lake Victoria Crescent and the Kyoga Plains. Four improved varieties (NARO-CASS 1, NASE 14, NASE 3 and I92/0067) and two Landraces (Njule red and Alado Alado), were used. Lower leaf samples were picked monthly and counts of parasitized and apparently healthy 3rd and 4th instars nymphs were made using a binocular microscope in the laboratory. Parasitism was expressed as a percentage of the number of nymphs parasitized to total number of nymphs present per leaf. A parasitized

nymph was defined by displaced mycetomes and colour change (black with meconia and orange shiny pupal skin). Results revealed two parasitoids, Encarsia sp. and Eretmocerus sp. that respectively contributed 57.5% and 21.2% parasitism levels. There was no significant difference (P>0.118) in parasitism across the different varieties. Parasitism however, differed significantly (P-crystallin/sHSP family (Bthsp19.5, Bthsp19.2, and Bthsp21.3) from B. tabaci. The three cDNAs encoded proteins of 171, 169 and 189 amino acids with calculated molecular weights of 19.5, 19.2 and 21.3 kDa and isoelectric points of 6.1, 6.2 and 6.0, respectively. The deduced amino acid sequences of the three genes showed strong similarity to sHSPs identified in two Lepidopteran species. All three sHSPs genes from B. tabaci lacked introns. Real-time quantitative PCR analyses revealed that the three BtsHSPs genes were significantly up-regulated in B. tabaci adults and pupae during high temperature stress (39, 41, 43, and 45 degree Celsius) but not in response to cold temperature stress (-6, -8, -10, and -12 degree Celsius). The expression levels of Bthsp19.2 and Bthsp21.3 in pupae was higher than adults in response to heat stress, while the expression level of Bthsp19.5 in adults was higher than pupae. In conclusion, our results show that B. tabaci sHSP genes have distinct regulatory roles in the physiology of B. tabaci under thermal stress.

Key words: sHSPs, Bemisia tabaci, developmental stage, expression pattern, thermal stress

Proteomic analysis of the interactions between TYLCV CP and its vector proteins reveals the role of Tid in constraining viral retention Author: Jing Zhao Co-authors: Tao Guo, Teng Lei, Wen-Qiang Xia Begomoviruses were exclusively transmitted by whitefly Bemisia tabaci in a persistent circulative manner. However, the interactions between begomovirus and whitefly were poorly known. In the present study, yeast two-hybrid system was used to identify the proteomic interactions of a begomovirus (tomato yellow leaf curl virus, TYLCV) with its whitefly vector. Totally, 20 proteins of B.tabaci were shown to interact with the coat protein (CP) of TYLCV. GO and KEGG pathway analysis showed that these 20 whitefly proteins interacting with TYLCV coat protein (CP) belonged to different classifications, including signal transduction, immune system, transportation, etc. Further experiments confirmed that tumorous imaginal discs (Tid), a protein involved in immune response, had a stable interaction with TYLCV CP, and the 300-419aa of Tid maybe the viral binding site. Feeding whiteies with dsRNA or antibody against Tid resulted in improving TYLCV level in whitefly body following viral acquisition, suggesting a role of Tid in whitefly immune response against TYLCV.

Whitefly transmission, host range, and cloning of a Datura isolate of the torradovirus, tomato necrotic dwarf virus Author: William Wintermantel Co-authors: Laura Hladky, Arturo Cortez Tomato necrotic dwarf virus (ToNDV; genus Torradovirus, family Secoviridae) is a whitefly-transmitted virus that caused significant losses for tomato production in southern California during the 1980s, and recently reemerged in central and southern California. The virus produces icosahedral virions approximately 30 nm in diameter, and can be transmitted by at least three whitefly species; Bemisia tabaci (MEAM1 and NW), Trialeurodes abutiloneus, and T. vaporariorum. Tomato (Solanum lycopersicum) is the primary crop affected by ToNDV. Fruit of infected tomato plants are severely scarred and unmarketable, and contain very few seeds. Some tomato varieties are

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known to exhibit resistance to torradoviruses, but little information exists regarding resistance to ToNDV. Whitefly transmission was efficient and comparable with both T. abutiloneus and B. tabaci MEAM1, whereas transmission by T. vaporariorum was less efficient in laboratory studies. A ToNDV isolate obtained from Datura discolor plants from Imperial Co., California in 2015 (ToNDV-D) was determined to have milder symptoms on tomato and greater sequence divergence from known ToNDV isolates collected from tomato. Like other ToNDV isolates, the ToNDV-D genome is composed of two RNA molecules of 7.2 and 4.9 Kb. RNA1 contains a large ORF encoding a 241 KDa polyprotein necessary for virus replication. RNA2 encodes two ORFs, with the latter expressed as a 133 KDa polyprotein that is proteolytically processed into movement and capsid proteins. The closest relative of ToNDV is Tomato marchitez virus at 83% and 91% identity for the RNA1 and RNA2 polyproteins, respectively. Sequence identity for other tomato-infecting members of the Torradovirus genus range from 63-82% for the RNA1, and 69-91% for the RNA2 polyproteins. The ToNDV-D isolate was cloned into the Agrobacterium vector, pJL89, and used to evaluate the host range and symptom expression of this isolate on several plant species. Results found 100 percent infection of three tomato varieties, but the common research variety, Moneymaker, remained symptomless although all plants inoculated became infected. Studies demonstrated efficient whitefly transmission from tomato plants agroinoculated with the cloned ToNDV-D isolate. In addition to tomato, ToNDV-D was shown to infect several other species within the Solanaceae, but most non-solanaceous hosts tested to date did not become infected. Interestingly, transmission efficiency using agroinoculation was much more efficient than mechanical, graft, or even whitefly transmission, and whitefly transmission from agroinoculated plants resulted in greater symptom severity on tomato plants, suggesting possible differences among inoculation methods for virus accumulation or translocation within the plant.

Comparison of transovarial transmission of Tomato yellow leaf curl virus by seven cryptic species of the Bemisia tabaci whitefly complex indigenous to China Author: Qi Guo Co-authors: Shusheng Liu, Xiaowei Wang Geminiviruses have emerged as a group of the most important insectborne plant viruses of agricultural significance in the past decades. These viruses are known to be maintained through plant-insect-plant cycle. However, other routes of transmission of the viruses remained largely unknown. A recent study reports that two cryptic species, named Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED), of the B. tabaci complex can efficiently transmit Tomato yellow leaf curl virus (TYLCV) to their offspring via ova. To further explore this phenomenon, we analyzed the capacity of transovarial transmission of TYLCV by seven other species of whitefly complex from China including Asia 1, Asia II 1, Asia II 3, Asia II 6, Asia II 7, China 1, and China 2. First, PCR detection of TYLCV DNA in the hemolymph of viruliferous adults as well as the immune-fluorescence detection of virus signals in midgut and primary salivary glands were performed. Our data showed presence of TYLCV virions in both the hemolymph and salivary glands of all the seven species of whiteflies, indicating that TYLCV could cross the midgut wall of the whiteflies. Next, we examined the capacity of TYLCV transmission by viruliferous adults of the seven species of whiteflies and found that all of them could transmit TYLCV to uninfected tomato plants. Finally, we examined the transovarial transmission TYLCV by each of the seven species of whiteflies. While we were unable to detect TYLCV virions in the eggs of viruliferous Asia II 7, TYLCV virions were detected at 1%~5% in the eggs of viruliferous Asia 1 and Asia II 6 and at about 30%~68% in the eggs of viruliferous Asia II 1, Asia II 3, China 1, and China 2. Moreover, TYLCV virions were detected at 50%~56% in the nymphs of viruliferous Asia II 3 and China 1. However, TYLCV DNA could not be detected in the offspring adults of all the seven whitefly species. These findings indicate that TYLCV could not be effectively transmitted to offspring via ova by the indigenous species of whiteflies examined in this study.



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Performance of Bemisia tabaci MEAM1 and Trialeurodes vaporariorum on healthy and Tomato chlorosis virus infected tomato plants and efficiency of virus transmission

Changing a paradigm in plant virus transmission: an aphid-borne polerovirus switches its vector to the whitefly Bemisia tabaci

Author: Luis Fernado Maranho Watanabe Co-authors: Vinicius Henrique Bello, Bruno Rossitto De Marchi, Maria Marcia Pereira Sartori, Marcelo Agenor Pavan, Renate Krause-Sakate

Author: Murad Ghanim

Whiteflies are important pests and causes great damage especially as vector of viruses. In Brazil, Bemisia tabaci (Gennadius) Middle East-Asia Minor 1 (MEAM1) is the most widespread around the country, while the Trialeurodes vaporariorum (Westwood) is found in greenhouses and under mild temperature conditions. Both whiteflies species are known to transmit the Tomato chlorosis virus (ToCV), an important Crinivirus, which causes symptoms of interveinal chlorosis, leaf brittleness and leaf bronzing on tomatoes. Herein, we investigated the performance of B. tabaci MEAM1 and T. vaporariorum on ToCV-infected and healthy tomato plants. MEAM1 performance was dramatically affected by ToCV-infected plants in number of eggs hatched and number of adults emerged, decreasing 41.8% and 92.4%, respectively, when compared to healthy plants. Moreover, the survival rate [(number of adults/ number of eggs)*100] was strongly decreased by 78.8%. Comparing both whiteflies species, MEAM1 has a much better performance on healthy plants than T. vaporariorum (94.8 vs 29.5 adults emerged). However, on ToCV-infected plants, T. vaporariorum generates more adults than MEAM1 (18.5 vs 7.2 adults emerged) in a faster development time (23 vs 25 days). We also investigated the efficiency of transmission of ToCV by MEAM1 and T. vaporariorum. We found that MEAM1 (78.6% efficiency of transmission) is a better vector than T. vaporariorum (35.7%). We conclude that T. vaporariorum can establish in the field earlier than MEAM1 under conditions of high ToCV infection and despite the lower efficiency of transmission of ToCV, T. vaporariorum can be an important vector of ToCV.

The role of the whitefly, Bemisia tabaci (Gennadius), and farmer practices in the spread of cassava brown streak ipomoviruses Author: Ibrahim Umar Mohammed Co-authors: Midatharahally N Maruthi, Simon C Jeremiah Cassava brown streak disease (CBSD) is arguably the most dangerous current threat to cassava, which is Africa’s most important food security crop. CBSD is caused by two RNA viruses: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). The roles of the whitefly Bemisia tabaci (Gennadius) and farmer practices in the spread of CBSD were investigated in a set of field and laboratory experiments. The virus was acquired and transmitted by B. tabaci within a short time (5 – 10 min each for virus acquisition and inoculation), and was retained for up to 48 hr. Highest virus transmission (60%) was achieved using 20 – 25 suspected viruliferous whiteflies per plant that were given acquisition and inoculation periods of 24 and 48 hr, respectively. Experiments mimicking the agronomic practices of cassava leaf picking or the use of contaminated tools for making cassava stem cuttings did not show the transmission of CBSV or UCBSV. Screenhouse and field experiments in Tanzania showed that the spread of CBSD next to spreader rows was high, and that the rate of spread decreased with increasing distance from the source of inoculum. The disease spread in the field up to a maximum of 17 m in a cropping season. These results collectively confirm that CBSV and UCBSV are transmitted by B. tabaci sem-ipersistently, but for only short distances in the field. This implies that spread over longer distances is due to movements of infected stem cuttings used for planting material. These findings have important implications for developing appropriate management strategies for CBSD.

Poleroviruses, like all other members of Luteoviridae are phloemlimited RNA viruses, which are exclusively transmitted by several aphid species. In the last decade, polerovirus species have been on the rise due to frequent recombination events between members of this group. Symptoms of vein yellowing, leaf rolling and fruit discoloration caused by polerovirus species transmitted by aphids are constraint to global pepper cultivation. A recent outbreak with such severe symptoms in pepper cultivations in Israel, despite low aphid population, led to reinvestigating the disease and its transmission by insect vectors. This study led to the association of a new recombinant polerovirus species with this outbreak and strikingly demonstrate a shift in its insect vector from aphids to the whitefly Bemisia tabaci. Full genome of this recombinant virus, tentatively named as Pepper whitefly borne vein yellow virus (PeWBVYV) was characterized. PeWBVYV shares homology (>95%) with Pepper vein yellow virus (PeVYV) described from Israel and Greece on its 5’ end half while being homologous to African eggplant yellow virus on the 3’ half. A recombination event between the two viruses at the boundary of ORF2, encoding the replicase protein was confirmed. The recombinant PeWBVYV was not transmissible by aphids but was transmitted by B. tabaci MEAM1 species by more than 70% efficiency. Furthermore, a constructed infectious clone of PeWBVYV was infective to Nicotiana benthamiana and pepper plants and was transmissible with B. tabaci, producing similar symptoms as the wild-type virus. Instances of such insect vector shift is rare in nature with much epidemiological significance such as capability of long distance spread by whiteflies and redefines the variables for polerovirus risk assessment. This highlights the global threat posed by the rapid evolution of plant pathogenic viruses and their insect vectors.

The whitefly transmitted Cowpea mild mottle virus can be an important component to reduce productivity of soybean in Brazil Author: Felipe Barreto da Silva Co-authors: Cristiane Muller, Vinicius Henrique Bello, Luis Fernando Maranho Watanabe, Bruno Rossitto De Marchi, Lucas Machado Fusco, Marco Antonio Tamai, Lucia Vivan, Guilherme Barbosa Minozzi, Renate Krause-Sakate Cowpea mild mottle virus (CpMMV) is a whitefly-transmitted virus and has been recognized as an emerging soybean (Glycines max) disease in Brazil. In soybean fields, the Bemisia tabaci (Gennadius) Middle East-Asia Minor 1 (MEAM1), commonly known as biotype B, is the most widespread species and it causes direct damage through sap suction and indirect damage as virus vector, also excreting honeydew during feeding, favoring the grown of the sooty mold. Once CpMMV is an emergent virus, there is no data about the losses caused by the virus in soybean. The experiments were conducted on four different fields of Brazil (corresponding to São Paulo, Mato Grosso and Federal District States), testing seven soybean varieties. Around 1000-soybean plants/variety were sap inoculated using soybean CpMMV infected leaf extracts. The productivity of the cultivars was determined as well as the plant height, pods per plant and grain weight. The symptoms observed for the virus infection was from symptomless plants to plant reduction and mosaic. Significant differences in the plant height, pods per plants and grain weight was observed for the different genotypes tested, and the reduction on yield production was around 5 to 10 sacks per hectare compared to the healthy plants, that is highly significant to soybean production. These results indicates that CpMMV, even asymptomatic on some genotypes, reduces productivity of soybean. The whitefly management to reduce virus transmission on soybean needs to be better evaluate to reduce the impact of CpMMV in the culture.

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Oral Abstracts Real time portable genome sequencing for global food security Author: Laura Boykin Co-authors: Ammar Ghalab, Bruno Rossitto De Marchi, Anders Savill, James M. Wainaina, Tonny Kinene, Stephen Lamb, Myriam Rodrigues, Monica A. Kehoe, Joseph Ndunguru, Fred Tairo, Peter Sseruwagi, Charles Kayuki, Deogratius Mark, Joel Erasto, Hilda Bachwenkizi, Titus Alicai, Geoffrey Okao-Okuja, Phillip Abidrabo, Emmanuel Ogwok, John Francis Osingada, Jimmy Akono, Elijah Ateka, Brenda Muga, Samuel Kiarie Kiarie The United Nations has listed Zero Hunger as one of the 17 global sustainable development goals to end extreme poverty by 2030. Plant viruses are a major constraint to crop production globally, causing an estimated $30 billion in damage and leaving millions of people foodinsecure. In Africa, agriculture employs up to 50% of the workforce, yet only contributes 15% to the GDP on average, suggesting that there is low productivity and limited value addition. This can be addressed through continued innovation in the fields of science and technology, as suggested in the Science Agenda for Agriculture in Africa (S3A). Sustainable management of plant viruses and their associated vectors must include efficient diagnostics for surveillance, detection and identification to inform disease management, including the development and strategic deployment of virus resistant varieties. To date, researchers have been utilizing conventional methods such as; PCR, qPCR, high-throughput sequencing (RNA-Seq, DNA-Seq) and Sanger sequencing for pathogen identification. However, these methods are both costly and time consuming, delaying timely control actions. The emergence of new tools for real-time diagnostics, such as the Oxford Nanopore MinION, have recently proven useful for the early detection of Ebola and Zika, even in poorly resourced laboratories. For the first time globally, the MinION portable pocket DNA sequencer was used to sequence whole plant virus genomes. We used this technology to identify the begomoviruses causing the devastating cassava mosaic virus, which is ravaging smallholder farmers’ crops in sub-Saharan Africa. Cassava, a carbohydrate crop from which tapioca originates, is a major source of calories for over 800 million people worldwide. With this technology, farmers struggling with diseased crops can take immediate, restorative action to improve their livelihoods based on information about the health of their plants, generated using a portable, real-time DNA sequencing device.

Unusual occurrence of a DAG motif in the Ipomovirus Cassava brown streak virus Author: Monica Kehoe Co-authors: Elijah Ateka, Titus Alicai, Joseph Ndunguru, Fred Tairo, Peter Sseruwagi, Samuel Kiarie, Timothy Makori, Laura Boykin Cassava is the main staple food for over 800 million people globally. Its production in eastern Africa is being constrained by two devastating Ipomoviruses that cause cassava brown streak disease (CBSD); Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), with up to 100% yield loss for smallholder farmers in the region. To date, vector studies have not resulted in reproducible and highly efficient transmission of CBSV and UCBSV. Most virus transmission studies have used Bemisia tabaci (whitefly), but a maximum of 41% U/CBSV transmission efficiency has been documented for this vector. With the advent of next generation sequencing, researchers are generating whole genome sequences for both CBSV and UCBSV from throughout eastern Africa. We have generated 8 new whole genomes (3 CBSV and 5 UCBSV) from Kenya, and in the process of analyzing these genomes together with 26 previously published sequences, we uncovered the aphid transmission associated DAG motif within coat protein genes of all CBSV whole genomes at amino acid positions 52-54, but not in UCBSV. Upon further investigation, the DAG motif was also found at the same positions in two other Ipomoviruses. Until this study, the highly-conserved DAG motif, which is associated with aphid transmission was only noticed once, in one other Ipomovirus, but discounted as being of minimal importance. This research represents the first comprehensive look at Ipomovirus genomes to determine the extent of DAG motif presence and significance for vector relations. The presence of this motif suggests that aphids could potentially be a previously unconsidered vector of some of these viruses. Further transmission and ipomoviral protein evolutionary studies are needed to confirm this hypothesis.

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Panoramic situation of whiteflies in Brazil and the efficiency of the different cryptic species to transmit viruses Author: Renate Krause-Sakate Co-authors: Bruno Rossitto De Marchi, Vinicius Henrique Bello, Luis Fernando Maranho Watanabe, Felipe Barreto, Lucas Fusco, Cristiane Muller, Regiane Cristina Oliveira de Freitas Bueno, Valdir Atsushi Yuki, Laura Boykin, Marcelo Agenor Pavan Bemisia tabaci is a polyphagous insect in many agricultural crops and a successful vector of plant viruses. B. tabaci is a cryptic species complex of at least 40 different species and four species were reported in Brazil: the two indigenous New World 1 and New World 2 and the two invasive Middle East-Asia Minor 1 (MEAM1), present in Brazil since the 1990s, and the Mediterranean (MED) reported in 2014 in the South and in 2017 in the Southeastern Brazil. In order to verify the distribution of the recently introduced MED in Brazil, whiteflies were collected from different locations and hosts throughout the country between the years of 2013 and 2017. The whitefly species was identified by molecular analysis of the mtCOI gene and the detection of endosymbionts present in the samples was carried out. The survey revealed that the MEAM1 species is still the prevalent found on major crops across Brazil and the only species present in North, Northwestern and Central Brazil confirming that this species is associated with the severe outbreaks of viruses in tomato and beans in our country. MED species was found in five different States infesting mainly ornamental plants in greenhouses but also other important vegetable crops such as sweet pepper, tomato and cucurbits, being sweet pepper heavily affected by this species. The two native B. tabaci species (NW1 and NW2) were found on weeds and soybean. The distribution of endosymbionts in MED was heterogeneous, indicating different invasions, but for MEAM1, Hamiltonella and Richettsia were highly frequent. In order to verify the ability of MED to transmit the main whitefly-transmitted viruses in Brazil, assays were performed to evaluate the transmission of the begomovirus Tomato severe rugose virus to tomatoes, Bean golden mosaic virus to beans and the carlavirus Cowpea mild mottle virus to beans. The results suggest that MED is as good as MEAM1 to transmit the assessed viruses and should be considered a menace to agriculture. Different aspects such as the effects of different viruses on MED and MEAM1 and the consequences of it for the epidemiology of viral diseases will also be presented.

Influence of plant-produced volatile chemicals towards host-selection behaviour of the cassava whitefly B. tabaci Author: Latifa Mrisho Co-authors: James Legg, Daniel Maeda, Marcus Stensmyr Flying insects, such as the whiteflies, use plant-produced volatile chemicals to indentify suitable and unsuitable host plants. Several studies have shown that the whitefly Bemisia tabaci can discriminate odours produced by different plants and a variety of plant-produced volatile chemicals that have repulsive or toxic effects towards the whiteflies have been identified. The ability of the whiteflies to identify and discriminate the plant-produced odours depended on several factors including the type/species of the whitefly and the concentration of the plant-produced volatile chemicals. In the present study, the odour-guided behaviour of the cassava whitefly B. tabaci towards plant-produced volatile chemicals was investigated and the volatile chemicals that influenced the behaviour of the whiteflies were identified. Two-choice assays using head-space air from cassava (variety Albert and Kiroba) and non-cassava host plants (tomato, cotton and cowpeas) as well as a non-host plant (Lemongrass) was used to determine the odour preference of B. tabaci. Settling behaviour of the whiteflies was also assessed using free-choice behaviour assays. Gas-chromatography mass-spectrometry was used to identify the volatile chemicals produced by the plants studied. When allowed to freely-chose, the whiteflies had equal preference towards cassava and tomato but not lemongrass. Approximately seven times as many whiteflies settled on cassava and tomato than on Lemongrass. Whiteflies were neither repelled or attracted to volatile chemicals produced by healthy undamaged cassava and cowpeas but were slightly repelled by volatiles produced by cotton and tomato



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as well as whitefly-infested cassava plants. Lemongrass and miteinfested cassava plants were least preferred. Of the volatile chemicals obtained from the head-space air of the tested plants, terpenes (from tomato and cotton), geranyl nitrile (from mechanical damaged cassava plants) and methyl salicylate (mite-infested cassava plants) as well as geraniol and citral (from lemongrass) were thought to be responsible for repelling the whiteflies. On-going studies are investigating how these plant-produced volatile chemicals elicit a behaviour response in the whitefly B. tabaci through identifying the olfactory receptors responsible for odour perception in the whiteflies and the chemical cues these receptors respond.

Nymph mortality – a potent mechanism of whitefly resistance in Medicago sativa L. (alfalfa) Author: Linda Walling Co-authors: Patrick Thomas, E. Charles Brummer There are few genetic mechanisms for controlling the invasive and crop-damaging whiteflies of the world. A potent resistance mechanism that controls the whitefly Bemisia tabaci B (MEAM1) was identified in alfalfa (lucerne, Medicago sativa L). This resistance is trichome independent, phloem mediated and manifested as death of first-instar nymphs. Alfalfa’s resistance prevents whitefly population expansion and has immense potential to enhance crop productivity in regions with strong whitefly pressure. Alfalfa populations were selected for hyper-susceptibility (C-1) and resistance (C+4 and C+7). To identify highly resistant and susceptible individuals within these populations, we developed a high-throughput phenotypic screen of alfalfa seedlings. The C-1, C+4 and C+7 populations display a spectrum of resistance indicating the multigenic nature of whitefly resistance. Three highly resistant and one highly susceptible alfalfa clones were used to determine the performance of MEAM1, B. tabaci A (NW1), and B. tabaci Q (MED1) on resistant and susceptible clones. The species specificity of alfalfa’s resistance and a model for the impact of resistance on population expansion will be reported. In addition, individuals from the C-1, C+4 and C+7 populations were used in a bulked, genotype-by-sequencing (GBS) strategy to identify the loci associated whitefly resistance. For each population, DNAs were isolated from 100 individuals. DNAs were pooled (25 plants/pool), digested with ApeKI, ligated to adapters and barcodes, amplified and sequenced. After removing the barcode tags, the sequence reads were aligned to the diploid M. sativa (CADL) genome and subsequently mapped to M. truncatula reference genome. Over 14,000 loci showed an allele frequency changes after cycles of selection for whitefly resistance. Two loci with the largest allele frequency changes were identified on chromosomes 8 and 3. Analysis of genes within these regions identified two candidate R genes. Surprisingly, these regions do not harbor nucleotide-binding leucine rich receptor (NLR) genes, which have been associated with resistance to aphids and planthoppers. Polymorphisms in the candidate R genes in resistant and susceptible genotypes are being determined. The nature of the putative whitefly resistance loci will be presented.

build-up. Even in the absence of early season beneficial disruptions, agronomic management and the plant physiology of Bollgard III cotton can reduce the effectiveness of whitefly sprays as dense canopies prevent adequate application of chemical to the target. In seasons where whitefly management fails, the potential losses due to discolouration of lint have led to a search for mitigation options that can remove honeydew or fungal contamination from open bolls. While rainfall may reduce the amount of honeydew on cotton bolls, it also supports fungal growth, and the amount and duration of rainfall in honeydew mitigation is critical. Short heavy showers followed by a dry period wash about 80% of honeydew off bolls without promoting sooty moulds. In contrast, an overcast and moist period may only partially alleviate honeydew and favour fungal growth. As weather factors are uncontrollable, Australian cotton growers are considering the use of fungicides to prevent or cure the occurrence of sooty mould spores. This presentation discusses the honeydew, sooty mould and weather interactions that affect cotton lint colour, and possible mitigation with conventional fungicides as well as novel compounds such as antifungal polymers and plant extracts.

Trend of whitefly (Bemisia tabaci) population on field grown cassava in Uganda Author: Tom Omara Co-authors: Sam Wamani, Patrick Ocitti, Sam Morris Opio, Geofrey Okao Okuja, Christopher Omongo Bemisia tabaci whitefly (Gennadius) a member of the order Hemiptera (suborder Homoptera) and family Aleyrodidae) is a pest and vector of most plants and plant viruses. In sub-Saharan Africa, B. tabaci is a major vector of Cassava mosaic Geminiviruses (CMGs) and Cassava brown streak viruses (CBSVs) which cause Cassava mosaic disease (CMD) and Cassava brown steak disease (CBSD) respectively. The two diseases are major constrains to cassava production in east and central African region. In Uganda, B. tabaci has been reported to cause widespread direct and indirect feeding damages to cassava crop. Increasing whitefly populations have been reported in Uganda from the time of CMD epidemic to date. Surveys are regularly conducted in Uganda to determine the abundance of B. tabaci at farm level, to map and relate it to CMD and CBSD incidence in the country so as to guide control interventions. Over a period of 3 years in 2011, 2013 and 2015, whitefly abundance surveys were conducted in 37 cassava growing districts across the 4 regions of the country. In each district, cassava fields were assessed for whitefly abundance at 5-8km intervals between fields or thereafter when a cassava field was found. Counts were made on 30 plants of the most predominant cassava variety across the two diagonals of each field. In total, 1,110 farmers’ fields were assessed yearly. Results revealed increase in average adult population from 2011 (6), 2013 (7) to 2015 (9) per region per plant and revealed an increase in mean whitefly abundance for the 3 years of study. Average whitefly population per plant per region over 3 years was highest in Central (10.9), east (7.7), Northern (7.3) West (6.6) and lowest in North West (3.8). Whitefly population was relatively abundant in regions surrounding water bodies.

Key words: Abundance, Survey, Management, Feeding damage, Region

Indirect whitefly/plant interactions: honeydew related factors affecting cotton lint quality and options for mitigation

Evaluation of whitefly parasitism on weeds, cassava and other crops in the field

Author: Simone Heimoana

Author: Yolice Tembo

Whitefly interactions with plants can be direct or indirect. One of the indirect effects of whitefly infestation of cotton is the deposition of honeydew on cotton lint late in the crop cycle. This contamination can lead to sticky cotton for which penalties can apply to individual cotton growers and, in extreme cases, to the entire industry. Honeydew contamination also provides opportunity for the growth of sooty mould fungal complexes on lint and the subsequent formation of black spores can incur significant penalties by changing the colour of cotton lint, which is an important quality factor in cotton pricing.

An experiment laid out in a randomised complete block design was conducted at Crop and Soil Sciences department research farm, Lilongwe University of Agriculture and Natural Resources, Bunda Campus in Lilongwe to investigate parasitism of whitefly on Compositae weed species, cassava, sweet potato, soybean and beans. The experiment ran from February to July, 2018. Percent parasitism tended to be higher in the weeds than in crops. This implies that weeds could be useful reservoir for whitefly parasitoids hence could be deliberately left to flourish in field margins of cassava.

While sound, IPM-based whitefly management is the best way of preventing honeydew and associated problems in cotton, early season mirid management can interfere with an IPM approach by disrupting beneficial insect species that contribute to whitefly population

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Oral Abstracts Enhancing Watermelon with Resistance against Whiteflies Author: Alvin Simmons Co-authors: Robert Jarret, Charles Cantrell, Amnon Levi Whiteflies are notorious pests in agricultural crops around the world. They attack crop plants in both field and protected environments such as greenhouses. It is well known that the Bemisia tabaci species complex (Hemiptera: Aleyrodidae) is highly polyphagous. However, there is a wide range in acceptance and performance of B. tabaci among host plant species. Moreover, in addition to damage by feeding, excessive damage results from the many plant viruses that they transmit. The B. tabaci complex is by far the most problematic among whiteflies affecting crops. The cultivated watermelon (Citrullus lanatus var. lanatus) is among the crops affected by whiteflies and whitefly-transmitted viruses. With a relatively short generation time and high rate of oviposition, whitefly populations can quickly build on host plants like watermelon. Commercial watermelon cultivars share a narrow genetic base and are highly susceptible to whiteflies. However, there is wide genetic diversity among the species of Citrullus. The Citrullus colocynthis and C. ecirrhosus are perennial desert watermelon species with a broad genetic base and viable sources of resistance to insect pests and diseases of watermelon. One of these two species (C. colocynthis) is indigenous to arid regions of Northern Africa, the Mediterranean, and Southwest Asia, while the other (C. ecirrhosus) is indigenous to Southern Africa. Insecticide is a common and convenient tool for managing whiteflies and other arthropod pests in watermelon. Yet, because of many negatives associated with that strategy, a sustainable approach of using host plant resistance is desirable. Watermelon host plant resistance against arthropod pests is based on a combination of plant tolerance, antibiosis and non-preference. Thus, we used multiple types of assays to assess plant resistance against whiteflies (B. tabaci; MEAM1). We collected olfactometer, and choice and no-choice performance assays in comparing whiteflies on cultivated watermelon versus genotypes of the perennial desert species. The data clearly demonstrated plant resistance against B. tabaci in the wild genotypes. Using traditional breeding procedures, we have been able to successfully cross C. colocynthis with watermelon cultivars (C. lanatus var. lanatus) and produced viable seeds. This research with genotypes of C. colocynthis and C. ecirrosus demonstrates their potential as sources of resistance against whiteflies for cultivated watermelon.

Biological Control Informed Thresholds for Enhancing IPM of Whiteflies in Cotton Author: Steve Naranjo Co-authors: Tim Vandervoet, Peter Ellsworth Economic thresholds are a cornerstone of modern Integrated Pest Management (IPM), allowing pest managers to make rational decisions on the need to control pest populations in agricultural systems. The concept has its roots in Integrated Control, a philosophy and approach to pest management that values and seeks to integrate the contributions of chemical and biological control. Despite explicit recognition of the value of biological control in IPM, most thresholds developed and deployed to date have focused exclusively on pest abundance as the decision metric. A suite of generalist arthropod predators prey on whiteflies and are a primary source of mortality in Arizona’s low desert cotton production system. We incorporated these natural enemies into pest control decision-making as a means of increasing the efficiency of control as well as reducing risk to growers. Experimentally, arthropod predator and whitefly populations were manipulated with a range of broad-spectrum and selective insecticide exclusions to vary predator to prey interactions in a 2-year field study. Predator to prey ratios associated with whitefly densities near the existing action threshold were estimated for six predator species found to be negatively associated with either adult and/or large whitefly nymphs. These included the crab spider Misumenops celer, a predatory dance fly Drapetis nr. divergens, the big-eyed bug Geocoris pallens, the minute pirate bug Orius tristicolor, the green lacewing Chrysoperla carnea s.l., and the predatory beetles Collops spp. Predator to prey ratios ranged from 1 M. celer per 100 sweeps to 1 whitefly adult per leaf to 44 D. nr. divergens per 100 sweeps to 1 large nymph per leaf disk. These

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ratios represent biological control informed thresholds that could function as simple-to-use decision tool for reducing risk in our current whitefly IPM strategy. High predator populations would act to delay or even eliminate the need for insecticidal control, thereby preserving crop value and saving growers money associated with control costs. But when predator populations are low, insecticidal control may be necessary in advance of the existing, prey centric, threshold. As predicated by the Integrated Control Concept, biological control should be used in concert with chemical control to most efficiently manage pest populations. Through the use of the biological control informed thresholds demonstrated here, biological control explicitly assumes a central role in pest control with potential benefits accruing to growers, consumers and the environment. Such approaches should be more fully explored and developed in many agricultural systems.

Implementing an IPM program for Silverleaf whitefly in vegetable crops Author: Siva Subramaniam Co-authors: Verni Sivasubramaniam, Sue Heisswolf, Robin Gunning, Mary Firrell Since its establishment the late 1990’s, the exotic pest Silverleaf whitefly (SLW), Bemisia tabaci Biotype B, has caused severe economic losses in vegetable and field crops across Queensland. In the vegetable industry, these losses are estimated at over $500 million through direct crop losses, cost of chemical control, loss of jobs and personal income. Over more than two decades, research focused on developing integrated management strategies for SLW that addressed key industry issues such as insecticide resistance and availability of new selective chemistry. In 2002, CSIRO imported the SLW parasitoid Eretmocerus hayati and started releases in late 2004 to establish the wasp in the Australian environment. In 2006, DAF researchers established a mass-rearing unit for E. hayati at the DAF Bowen Research Facility in North Queensland. The aim was to integrate E. hayati releases with compatible pesticides to implement a practical integrated pest management (IPM) program with growers and industry at the farm and district level. Researchers used crop monitoring results to make management decisions based on the relative level of whiteflies to parasitoids. Actions were triggered by tentative threshold levels which were adjusted to crop phenology and changes in parasitism levels. Targeted E. hayati releases were the main control strategy in this IPM program. Selective insecticides such as pyriproxyfen, pymetrozine and spirotetramat were used, but only when necessary. Post-release evaluation results clearly demonstrated that E. hayati releases played a significant role in SLW control with parasitism levels of 30 to 80 % recorded in most crops including melons, tomato and pumpkin. Best farm practices played an important role in suppressing SLW numbers. These included location of plantings, effective pesticide application and timely crop residue management at harvest. A critical farm practice that was widely promoted to growers and industry was a ‘crop clean-up’ strategy to prevent adult SLW migration from harvested crops into adjacent younger crops. Building industry confidence through collaboration were key factors for successful IPM implementation. The project team achieved this through long-term and intensive on-farm development work with growers, agronomists and consultants. The program was externally evaluated in 2008 and E. hayati is now commercially available for release on SLW susceptible crops. In this paper, we summarise results and describe some of the challenges faced during the development and implementation of the IPM program on commercial farms.



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Audacious Insect Control Approaches for an Impatient Optimist Author: Marie Connett Co-authors: Arty Makagon Approaches to control of insects that damage farm crops and livestock may be informed by the technical feasibility, effectiveness, costs, and experience of approaches to control of insects that vector human diseases. To counter pesticide resistance and other side effects such as detriment to food chains that result from last-century approaches to control of malaria/dengue-bearing mosquitos, Global Good, a private sector innovation fund created for Bill Gates and located in a purposebuilt lab to harness the power of invention for the achievement of large goals, developed a physical targeting system aimed at mosquitos of disease-bearing species. In proof-of-concept work, the system effectively targets only actively flying females of these species. The same device has been re-tuned and is now being tested against psyllids that carry a bacterial disease debilitating to citrus crops. Proof-of-concept data similarly show good avoidance of non-target insect species. While due to high cost and other factors this same system may not currently be suitable for targeting whiteflies of the Bemisia tabaci species complex carrying crop viruses in Africa, this will be discussed as an instructive example of how a technology idea involving audacious lateral thinking could be considered for its potential to “move the needle” and subjected to further de-risking. Global Good seeks to use Design for Social Impact principles to select from among such ideas with objectives of reducing risks and costs to create products that are safe, sufficiently rugged, and appropriately powered and priced for low-resource settings.

Management of Cowpea mild mottle virus and the whitefly vector in beans Author: Denis Persley Co-authors: Peter Nimmo, Cherie Gambley, Visnja Steele The whitefly transmitted Cowpea mild mottle virus (CPMMV, family Betaflexiviridae, genus Carlavirus was detected in Queensland in 2016. This was the first detection of the virus in Australia and of Carlavirus infection of Fabaceae species in Australia. The virus has been found in all green bean production areas in Queensland and is a threat to the industry because of the high susceptibility of currently used varieties, the long production periods in various regions and the distribution and abundance of the vector. The known natural hosts of CPMMV in Queensland are bean, soybean, mung bean, cowpea and several perennial legume species. In bean, the virus causes leaf mottling, stunting and discolouration and distortion of bean pods. The latter has resulted in considerable economic impact in the green bean industry through failure to harvest crops and downgrading of consignments in packing houses. Although most Carlaviruses are transmitted by aphids, members of the CPMMV clade are transmitted by the silver leaf whitefly Bemisia tabaci. Several Queensland isolates were transmitted by Bemisia tabaci (Middle East Asia Minor 1) following exposure of young bean plants to whitefly previously allowed access to CPMMV infected bean plants. Surveys have been undertaken over three seasons in south Queensland to determine the dynamics of white fly populations in bean crops and correlate insect numbers with CPMMV incidence. This work will be discussed in the presentation. A management plan for CPMMV in beans entails vector monitoring, strategic insecticide applications, release of parasites and selection of tolerant varieties.

Expression of an insecticidal fern protein in cotton protects against whitefly Author: Manisha Mishra Whiteflies are minute sap feeders that cause significant economic damage to several crops worldwide. The way whiteflies cause damage to plants is not new to the scientific community. It is the whitefly vectored plant viruses that cause major crop losses around the globe. Among whiteflies, Bemisia tabaci has arisen as a key

pest of agriculture and is counted among the World›s 100 worst invaders. Various control stratagems are being applied under the umbrella of Integrated Pest Management (IPM) to combat the pest. Being nonspecific in their actions, insecticides are often unsafe to the beneficial insects and are also vicious to the ecosystem. Above and beyond, the pests develop resistance to pesticides very quickly; therefore its control is always a challenging task. Other strategies viz; cultural control methods, biological control agents or host plant resistance in cultivated varieties are also implemented to deal with the problems related to chemical control and are known to offer protection with limited success. IPM programs encompassing such strategies are constantly specific to the crop, season and/or the geographical region. Therefore, exploration of unconventional approaches for the control of B. tabaci is an unmet need. The hypothesis behind the present study is that – if we control the vector, the spreading of harmful viruses will automatically be controlled. To prove the hypothesis, protein based solution to combat the vector was discovered following the exploration of lower plant biodiversity. It is noteworthy that none of the insecticidal proteins used in genetically modified (GM) crop plants to date are effective against whiteflies. Here, we report the discovery and characterization of a novel insecticidal protein viz; Tma12 from an edible fern, Tectaria macrodonta. The median lethal concentration was recorded to be 1.49 mg/ml in in vitro feeding assays. Tma12 interferes with life cycle of B. tabaci at sub-lethal doses. For functional characterization of newly discovered insecticidal protein, gene encoding Tma12 was introduced into cotton plants. Transgenic cotton lines with ~0.01% expression of Tma12 were found resistant to whitefly infestation in contained field trials, with no detectable yield penalty. Control of B. tabaci on GM cotton lines eventually offered protection against whitefly-borne cotton leaf curl viral disease. No histological or biochemical changes could be observed in Rats that were fed with Tma12. The protein was found to be devoid of any allergenic domains. Our study strongly advocates that Tma12 might be well suited for deployment in GM crops to control whitefly and the viruses it carries.

Bemisia tabaci insecticide resistance management in Australian cotton Author: Jamie Hopkinson The Silverleaf whitefly, Bemisia tabaci Middle East-Asia minor 1 (MEAM1) or B-biotype is a major introduced pest of Australian cotton, primarily due to its capacity to contaminate cotton lint with honeydew. Financial penalties for producing sticky cotton or lint colour downgrades as a result of sooty moulds that grow on contaminated bolls can be severe. Australia has an unparalleled reputation for exporting high quality cotton. Any failure to manage whitefly that results in sticky cotton would potentially jeopardise this reputation and lead to distrust of Australia’s ability to produce clean cotton. An integrated management approach to whitefly has therefore been adopted by the cotton industry, incorporating elements of biological control and farm hygiene, to minimise the build-up of populations to damaging levels at boll opening. However, in most years, many cotton fields still require a minimum of one spray for this pest, with the insect growth regulator, pyriproxyfen the most reliedupon insecticide. As insecticide resistance represents the largest threat to the sustainable management of B. tabaci in Australian cotton, a management strategy for selection and timing of insecticide application has been in place since whitefly first became a serious pest of cotton in 2002. Integral to the strategy is regular screening of whitefly populations to insecticides to determine the presence of resistance in whitefly populations from each cotton production region and to what extent any changes in susceptibility may have taken place over time. In this paper we will discuss the current insecticide resistance program for whitefly in Australian cotton, recent changes in insecticide resistance, the implications for industry, including its response to resistance detection, and how this is influencing IPM in the future.

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Oral Abstracts Field evaluation of synergists to overcome pyrethroid resistance in silverleaf whitefly Author: Siva Subramaniam Co-authors: Verni Sivasubramaniam Silverleaf whitefly (SLW), Bemisia tabaci Biotype B can be difficult to control in field and vegetable crops across Queensland. In vegetables, this exotic pest causes severe impacts by reducing yields, product quality and vectoring viruses. Initially pyrethroids, especially bifenthrin, were widely used to control the pest in vegetables however reports of spray failures on several farms during 1998 to 2004 pointed to increasing resistance problems. This paper reports on work to combat insecticide resistance to pyrethoids using the synergist Piperonyl butoxide (PBO). PBO is normally mixed with insecticides to block enzymes present in insects that are capable of breaking down the insecticide in question. For many years, PBO was considered a specific inhibitor of microsomal oxidases, but subsequent research revealed that it is also an inhibitor of enhanced esterase activity. In this study, we examined the synergism of bifenthrin and alphacypermethrin with two piperonyl butoxides (PBO) formulations (Enervate and NUQ-3313). Two pyrethroid only treatments, eight PBO/ pyrethroid combinations and an untreated control were evaluated against SLW on tomato. The treatments were applied three times at 12 to 14 days intervals. Systematic leaf and suction samples were taken to assess the egg, nymph and adult numbers in treated and control plots until harvest. The effect of treatments on fruit quality was also evaluated at harvest. Most of the PBO/pyrethroid combination treatments resulted in a significant reduction in adult SLW numbers (88 to 97%) and egg densities, compared to pyrethroid only treatments. Bifenthrin with both PBO combinations showed higher efficacy than the alphacypermethrin/PBO combinations against SLW in the field. Pre-spraying with PBOs 3 to 5 hours prior bifenthrin (split applications) provided better synergism and consistently resulted in fewer adults, eggs and nymphs as well as lower irregular ripening damage on fruit. Among tank-mixture combinations, NUQ3313 + bifenthrin performed better than all other treatments. Among the PBOs, NUQ3313 performed somewhat better than Enervate when combined with bifenthrin. Even after three applications, bifenthrin or alpha-cypermethrin only treatments did not give a significant level of control when compared to the untreated control plots. The percentage of marketable fruits was also higher in the PBO/ bifenthrin treatments than in the pyrethroid only and untreated control plots. Results demonstrated a high level of synergism when bifenthrin was combined with PBOs for controlling SLW. The PBO/pyrethroid combination is therefore a valuable, additional option within an insecticide resistance management program promoted to the vegetable industry.

Knockdown of gut dsRNAses to improve feeding RNAi efficiency of osmoregulatory genes in B.tabaci Author: Mridula Gupta Co-authors: Ramandeep Kaur, Satnam Singh, Suneet Pandher, Pankaj Rathore Whitefly (Bemisia tabaci) is serious pests of agricultural crops globally and its control is mostly relied on chemical insecticides. Double-stranded RNA (dsRNA)-mediated gene silencing, also known as RNA interference (RNAi), has been a breakthrough technology for functional genomics studies and represents a potential future tool for the management of insect pests. RNAi efficiency varies significantly across different insects groups due to prescence of nucleases which degrade the dsRNA before its processing into siRNA. In hemipterans, the gut nucleases act as major barrier in the feeding RNAi by degrading the dsRNA prior to processing of siRNA. To improve feeding RNAi efficiency in whitefly, dsRNA targeting Aquaporin (AQP) and Calcitonin (CAL) were coadministered with dsRNA against the nuclease genes (dsRNAsesI and dsRNAsesII) in synthetic diet. The

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dsRNA tageting nuclease genes (dsRNAsesI and dsRNAsesII) in the diet protect the dsRNA of AQP and CAL from degradation before the processing of dsRNA to siRNA. The dsRNA was synthesized in vitro using Ambion (Invitogen) T7 transcription system. Feeding was done using 400 ng/ul of dsRNA targeting AQP and CAL, dsRNAsesI and dsRNAsesII in 20% sucrose at room temperature for 48 hours. In case dsRNA targeting only AQP1 and CAL genes caused 23.74 and 87.69 per cent knockdown of targeted genes compared to control. On the other hand, dsRNA targeting AQP and CAL coadministered with mixture of dsRNAs of dsRNAsesI and dsRNAsesII caused 47.69 and 95.57 percent knockdown with significant t-test. As these genes are responsible for osomoregulatory functions, whiteflies were released on the water sensitive paper to count the water spots as compared to control. The spots counted were 0.03, 0.08, 0.16 spots/mm2 for dsRNA targeting mixture of dsRNAsesI, dsRNAsesII and CAL , CAL and GFP(Green Flouroscence protein) respectively. The results shed light on the improvement of feeding RNAi by targeting the genes which are responsible for dsRNA degradation or nuclease action in the insects. Hence, suppression of RNAi-suppressing nuclease genes results in protection of target dsRNA for efficient knockdown of the target genes (AQP and CAL).

SNP-genotyping using NextRAD sequencing unravels the genetic diversity of cassavacolonizing Bemisia tabaci Author: Everlyne N. Wosula Co-authors: Wenbo Chen, Zhangjun Fei, James P. Legg Bemisia tabaci, one of the most economically important pests worldwide, is the vector of cassava mosaic begomoviruses and cassava brown streak ipomoviruses which cause significant cassava yield losses in Africa. Cassava-colonizing B. tabaci comprise several cryptic species that have been distinguished using the mitochondrial DNA cytochrome oxidase I (mtCOI) sequence as the marker. New sequencing technologies, however, make it possible to examine genome-wide variability. The objectives of the study reported here were therefore to: (i) compare patterns of genetic diversity of cassava B. tabaci revealed by single nucleotide polymorphism (SNP)-genotyping vs mtCOI sequencing; and to (ii) determine if there is gene flow among these cryptic species. Ninety-five whitefly specimens collected from cassava in eight African countries were genotyped using NextRAD sequencing, and their phylogeny and population genetics were investigated using the resultant SNP markers. SNP marker and mtCOI data obtained from the same insect were compared. Eight genetically distinct groups were identified based on mtCOI, while phylogenetic analysis using SNPs identified six major groups. STRUCTURE analysis identified four ancestral B. tabaci populations that have contributed alleles to the six SNP-based groups. Significant gene flows were detected between several of the six SNP-based groups, and all groups were linked directly or indirectly through gene flow. This study reveals that mtCOI is not an effective marker for phylogenetic classification of cassava-colonizing B. tabaci, and that more robust SNP-based multilocus markers should be developed. Significant gene flows between populations could lead to the emergence of haplogroups that might alter the dynamics of cassava virus spread and disease severity in Africa. Continuous monitoring of the genetic composition of whitefly populations should be an essential component in efforts to combat cassava viruses in Africa.

Quality control of molecular data for defining Bemisia tabaci cryptic species status Author: Samia Elfekih Co-authors: Sona Vyskocilova, Paul De Barro, Andrew Poleszek, Sarina Macfayden, Karl Gordon, John Colvin, Thomas Walsh, Wee Tek Tay Concerted efforts from the research community are currently underway to identify the separate cryptic species within the major agricultural pest Bemisia tabaci. This is important in bolstering national and international biosecurity preparedness and for developing integrated pest management (IPM) strategies and resistance management plans (RMP). Species identification within the B. tabaci complex is best achieved through an integrative approach



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that considers mating compatibility, host-plant preferences, and molecular characterization including analyses of full mitochondrial genomes and genome-wide single nucleotide DNA markers. This integrated approach has recently enabled the identification of a new cryptic B. tabaci species within the ‘Africa/Middle East/Asia Minor’ clade. High throughput sequencing of full mitochondrial DNA genomes also provided evidence of species misidentification due to the erroneous characterization of nuclear mitochondrial genes (NUMTs). Evidence supporting the impact of NUMTs on B. tabaci species status can also be seen from the more powerful genomewide sequencing (i.e., Nextera Reductive Amplified DNA or NextRAD). This represents part of the current genomic effort to revolutionise the way we perceive species within the B. tabaci complex. In this study, we show how conflicting information about B. tabaci cryptic species, obtained from sequencing the partial mitochondrial DNA cytochrome oxidase I (mtCOI) gene, and from genome-wide single nucleotide polymorphic markers, can be resolved through stringent quality control of both mitochondrial DNA and high throughput sequencing data. As a starting point to future studies that rely on defining B. tabaci species status, we advocate that all partial mtCOI genes, including publicly available ones, be analysed as the first step to ensure erroneous sequences (i.e., due to sequencing errors and/or NUMTs) are removed. This applies also to mtDNA sequences in studies that involve genome-wide sequencing methods. With the majority of studies on B. tabaci cryptic species where an integrative approach is not always possible, our inability to ensure the reliability of molecular data could complicate efforts to identify separate species and identify appropriate management solutions. These delays can have a real impact, particularly for African subsistence farmers facing food security threat imposed by African cassava whitefly species.

Patterns of conflict between nuclear and mitochondrial cytochrome oxidase I (mtCOI) DNA phylogenies in Bemisia tabaci species complex Author: Tonny Kinene Co-authors: Laura Kubatko, Titus Alicai, Christopher Omongo, Ian Small, James Wainaina, Livingstone Luboobi, Laura Boykin The genetic diversity of the Bemisia tabaci species complex has been based on the mtCOI gene and mating experiments. The advent of new sequencing technology has made it possible to collect a vast number of multiple unlinked nuclear loci. It has been suggested that the mtCOI locus might not be an effective molecular marker for delimiting B. tabaci species. Therefore, a combination of the mtCOI and multiple unlinked nuclear loci might be important in defining species boundaries. In this study we generated 137 mtCOI gene sequences, 69 shaker cognate w and 44 RNA polymerase II gene sequences from East Africa whitefly species using the Sanger method. We investigated whether nuclear loci alone can be used to delimit members of B. tabaci species complex. We did this by making inference on Bayesian phylogenies and found out that nuclear gene tree topologies were not concordant with the mtCOI gene tree topology due to incomplete lineage sorting. Thus, a single nuclear molecular marker cannot delimit members of the B. tabaci species complex but a combination of several nuclear markers would be advantageous is generating a robust species tree.

Genetic diversity of mitochondrial DNA of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) associated with cassava and occurrence of cassava mosaic disease in Zambia Author: Patrick Chikoti

subgroups (SG): SSA1-SG1, SSA1-SG2 and SSA1-SG3. All three subgroups of SSA1: SSA1-SG1, SSA1-SG2 and SSA1-SG3 occurred in Western Province, while only SSA1-SG3 occurred in Eastern Province. SSA1-SG1 also occurred in North-Western and Luapula provinces. Mean adult B. tabaci populations were most abundant in Western Province in 2013 (11.1/plant) and 2015 (10.8/plant). The lowest B. tabaci populations (0.2/plant) were recorded in Northern Province in 2013 and 2015. Cassava mosaic disease was prevalent in all the seven provinces surveyed. CMD incidence was highest in Lusaka Province in both 2013 (78%) and 2015 (83.6%) and lowest in Northern Province in both 2013 (26.6%) and 2015 (29.3%). CMD symptom severity was more severe in Lusaka Province in both 2013 (3.4) and 2015 (3.9) and mild in Eastern Province in 2013 (2.8) and 2015 (3.1). The knowledge of B. tabaci species associated with CMD and their distribution in the country is key to guiding the strategic deployment of management strategies to ensure food security for millions of cassava dependant households.

Common and distinct gene expression changes in whitefly (Bemisia tabaci, MEAM1) after feeding on three virus-host plant combinations, and whitefly control through RNAi Author: Navneet Kaur Co-authors: Daniel Hasegawa, Everlyne N. Wosula, Wenbo Chen, Mware Bernard, Leena Tripathi, James Legg, Zhangjun Fei, Wayne Hunter, William Wintermantel Whitefly, Bemisia tabaci is a global pest that threatens production of numerous economically important crops including tomato, cotton, cucurbits, and cassava. In addition to feeding on 1000 different species of plants, the whitefly transmits over 300 different viruses. Prior to our work, little was known of how whitefly gene expression is altered when whiteflies feed on virus-infected plants. Tomato chlorosis virus (ToCV) and Cucurbit yellows stunting disorder virus (CYSDV); genus Crinivirus, family Closteroviridae, are transmitted by B. tabaci in a semipersistent manner and infect several globally important agricultural crops including tomato and melon, respectively. To determine changes in global gene regulation in whiteflies after feeding on crinivirus (ToCV and CYSDV) infected plants, comparative transcriptomic analysis was performed using RNA-Seq on whiteflies (Bemisia tabaci MEAM1) fed on either ToCV-infected tomato/CYSDVinfected melon, or virus-free plants. Significant differences in gene expression were detected between whiteflies fed on virus infected plants and those fed on uninfected plants, with 1155 differentially expressed genes (DEGs) found in ToCV whiteflies whereas only 221 DEGs were found in CYSDV whiteflies. Using a comparative transcriptomics approach, we also evaluated the gene expression profiles of whiteflies (B. tabaci MEAM1) after feeding on tomato infected by a persistently transmitted virus, Tomato yellow leaf curl virus (TYLCV); genus Begomovirus, family Geminiviridae, in comparison to the semipersistently transmitted criniviruses. Results revealed common gene expression changes, but also large differences between the different virus-vector-host plant systems in the number of whitefly genes differentially expressed when fed on virus infected plants. Our team has developed and tested the efficacy of 70 different dsRNAs designed against gene(s) critical to the life cycle of whitefly. The 10 most effective RNAi constructs showing the highest whitefly mortality through in vitro testing have been screened in three labs, the USDA-ARS (Salinas & Charleston) and IITA Labs (Dar es Salaam, Tanzania). Among the 70 dsRNA constructs tested against B. tabaci, MEAM1, six constructs produced high levels of mortality (96.1%, 79.4%, 66.7%, 59.4%, 65.6%, and 72.8%) with p-value = 0.0008 as compared to two negative controls (watermelon based gene- 33.9% and sucrose diet based- 27.8%). These six dsRNA constructs also showed promising results when tested against cassava whiteflies B. tabaci, SSA1-SG3 in IITA, Tanzania. RNAi hairpin constructs have been designed to transform tomato and cassava, and this work is in progress in Charleston, SC and IITA, Nairobi, Kenya.

A study to determine the genetic variability of Bemisia tabaci species associated with cassava was carried out using mitochondrial cytochrome oxidase I (mtCOI) gene sequences of samples collected from selected provinces of Zambia in 2013 and 2015. Phylogenetic analysis showed the presence of only sub-Saharan Africa 1 (SSA1) species in the country. SSA1 species was clustered into three

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Oral Abstracts CRISR/Cas9-mediated Genome Editing in the Whitefly, Bemisia tabaci Author: Peter Atkinson Co-authors: Simran Sandhu, Jun-Bo Luan, Angela Douglas, Linda Walling The whitefly Bemisia tabaci is an important pest of global agriculture through both the impact of its feeding on infested leaves and by vectoring pathogenic viruses to the plant host. Much genetic information has been acquired about viral genome structure and the mechanism of action of the transcripts and proteins encoded by them. In contrast, the genetic and biochemical basis of how infested plants respond to B. tabaci is now emerging. What is lacking is detailed knowledge of the genetic and biochemical pathways of B. tabaci behaviour that are responsible for its pestiferous behaviour. To date B. tabaci has remained refractory to genetic analysis despite having some features which should make is an ideal genetic model insect. We have developed a novel and simple insect-embryo microinjection system combined with a small footprint, cost-effective and secure method of rearing B. tabaci that have enabled us to introduce CRISPR/ Cas9-mediated mutations into its genome. We will describe this technology and how it will enable new genetic and chemical-based approaches to B. tabaci control to be developed.

Genome-wide profiles of miRNAs and piRNAs in whitefly Bemisia tabaci in response to feeding on tomato plants infected with Tomato yellow leaf curl virus Author: Daniel K. Hasegawa Co-authors: Md Shamimuzzaman, Wenbo Chen, Alvin M. Simmons, Zhangjun Fei, Kai-Shu Ling The whitefly Bemisia tabaci is a notorious vector transmitting hundreds of viruses that infect food and fiber crops worldwide. Recently, we sequenced the B. tabaci MEAM1 genome and profiled gene expression in whiteflies during feeding on tomato infected with Tomato yellow leaf curl virus (TYLCV). To investigate the regulatory mechanisms in whiteflies during TYLCV acquisition and transmission, we performed small RNA (sRNA) sequencing and conducted microRNA (miRNA) and Piwi-interacting RNA (piRNA) profiling of B. tabaci after feeding on TYLCV-infected or virus-free tomato for 24 h, 48 h and 72 h. A total of 160 miRNAs were identified, including 68 conserved and 92 novel miRNAs. Interestingly, only two miRNAs were differentially expressed in whiteflies that fed on TYLCV-infected or non-infected tomato, which had predicted targets to Bta05482 encoding a Nuclear receptor and Bta10702 encoding a very-longchain (3R)-3-hydroxyacyl-CoA dehydratase, respectively. To shed light on the relationship between B. tabaci regulatory miRNAs and gene expression, we correlated the miRNA expression with gene expression derived from a transcriptome data that was generated from the same pool of RNAs. Interestingly, approximately half of miRNAs were correlated inversely with their predicted target transcript expression. In a separate analysis, piRNAs were clustered along the whitefly genome, which aggregated in 57 to 96 clusters in sRNA libraries prepared in three time points. Comparative analysis across the three time points identified 53 commonly expressed piRNA clusters. We also identified five TYLCV-induced and 24 TYLCV-suppressed piRNA clusters. About 62% of all identified piRNAs were derived from sequences in intergenic regions, introns and UTRs, while the remaining 38% from coding sequences (CDS) and repeat elements. Six protein-coding genes were targeted by the TYLCV-induced piRNAs, but their functions in anti-viral defence or virus transmission are not known. Transposable elements targeted by piRNA clusters include both class I retrotransposons (e.g., Gypsy, Copia, and LINEs) and class II DNA transposons (e.g., MITE, hAT, and TcMar). Together, we have tied miRNAs and piRNAs with genomic and transcriptomic information to provide an in-depth understanding on the underlying mechanisms of B. tabaci during virus acquisition and transmission, which might facilitate the identification of novel targets for RNAi control of whiteflies.

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Silencing of Vitellogenin Gene In Bemisia Tabaci (Gennadius) Inhibits Fecundity And Egg Hatchnig Author: Vikas Jindal Co-authors: Geetika Banta, Sajjan Grover Vitellogenesis is the process of yolk formation via which the nutrients are deposited in the oocyte involved in reproduction. The most important protein precursor in vitellogenesis is vitellogenin (Vg), which is produced in the fat bodies then transported through hemolymph for incorporation into growing oocytes (eggs). In this study, function of vitellogenin gene (vit) in Bemisia tabaci was studied using RNAi technology. Two different regions (vg1 and vg2) of the gene from whitefly were amplified, cloned in pTZ57 R/T vector and nucleotide sequences were determined. The dsRNA corresponding to both the regions were synthesized using MEGAscript kit (Ambion). dsRNA corresponding to green fluorescent protein gene was used as control. dsRNA of vg1, vg2 and gfp gene @ 2.5, 1.0, 0.5 and 0.1 µg/ µl incorporated in artificial diet (20% sucrose solution), sandwiched between two layers of parafilm, were fed to whiteflies for 48 hours. After 48 hours, the whiteflies were shifted to cotton leaves in leaf cages and various biological parameters of whitefly were observed under stereozoom microscope. The blast anaylsis of nucleotide sequence of partial vg1 and vg2 cloned showed >97% homology to the vitellogenin gene of whitefly. Feeding of dsRNA for 48 hours affects the survival and reproduction of whitefly adults adversely in a dose dependent manner. Knockdown of vg gene resulted in 70.63 per cent mortality in dsvg1 followed by 65.58 per cent in dsvg2 @2.5 µg/µl as compared to dsgfp treatments (11.98 to 14.04 %). The fecundity was significantly minimum (4.78 eggs/female) in dsvg1 @ 2.5 µg/µl and dsvg2 @ 2.5µg/µl (5.63 eggs/ female) in comparison to control (23.65 eggs/female). Whiteflies fed with dsvg1 and dsvg2 @ 2.5 µg/µl, resulted in minimum longevity (2.63 and 2.58 days), which was statistically lower than all dsgfp treatments and control. Significantly higher egg mortality was recorded when the whiteflies were fed with dsvg1 (35.00%) and dsvg2 (32.80%) @ 2.5 µg/µl as compared to dsgfp and control. The number of viable eggs per female was minimum (0.82 eggs/female) when whitefly adults were fed with dsvg2 @ 2.5 µg/µl, dsvg1@ 2.5 µg/µl (0.88 eggs), dsvg1@ 1.0 µg/µl (3.04 eggs) and dsvg2@ 1.0 µg/µl (3.47 eggs) but significantly lesser than all dsgfp treatments (12.70 to 15.21 eggs/female) and control (16.58 eggs/female).These data suggest that vitellogenin gene acts as a major biological player in whitefly biology and further can be the potential target gene for further studies.

Optimum field sampling of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations: A management decision tool Author: Peter Sseruwagi Co-authors: Kalyebi Andrew, Mlaki Leonia, Mrosso Thomas, Chacha Pashal, Mark Deogratius, Tairo Fred, Ndunguru Joseph, Sarina Macfadyen Bemisia tabaci is a pest of economic importance in agriculture globally, due to vectoring of plant viruses and physical damage caused to the crops when in high abundance. In Sub-Saharan Africa (SSA) the losses due whiteflies and whitefly-transmitted viruses (WTVs) are estimated in billions of US$ annually. Many programmes and resources have been instituted to monitor whitefly population dynamics and disease epidemiology. However, a review of these efforts showed that field sampling was always carried in the ‘low season’ of the year, when whitefly populations are lowest. This is challenging, since surveys are based on one-time assessments, which tend to underestimate the whitefly populations and their impact in the cropping season. In this talk, I will highlight the data obtained on whitefly population dynamics in empirical studies that were assessed over several months in a cropping season and compare it with data collected in the field surveys, that are based on single assessments. I will answer five key questions to guide ‘optimum field sampling’: what?, why?, where?, when? and how?, and how the knowledge generated serves as a management decision tool for: (a) ascertaining periods of low or high B. tabaci abundance, (b) predicting new whitefly and whiteflyborne disease outbreaks and/or spread, (c) the strategic deployment of IPM options that could exploit periods and areas of low whitefly



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abundance, (d) guiding when and where to multiply and/or establish new crops, and (e) where to screen for whitefly host resistance. This knowledge is critical to developing sustainable management strategies for whitefly and whitefly-borne diseases in smallholder farming systems.

NURU, an artificial intelligence system for diagnosis of plant diseases and pests Author: Latifa Mrisho Co-authors: Neema Mbilinyi, Amanda Ramcharan, Peter McCloskey, David Hughes, James Legg Insect pests and diseases are major challenges to food production worldwide, with approximately 40% of crop yields lost to diseases alone. Accurate and early identification of pests and diseases are necessary for effective management. This is usually done through direct identification of the pest and disease symptoms in the field. In most developing countries, the majority of farmers do not know how to identify symptoms of pests and diseases affecting their plants, which prevents early detection. Here we introduce NURU, a tool that serves to improve and broaden the capacity of extension agents in developing nations to support farmers by acting as the media through which the expert knowledge for pest identification is transferred to extension agents. NURU is an artificial intelligence system for diagnosis of pests and plant diseases based on foliar symptoms. NURU was developed by PlantVillage (Penn State University), FAO and IITA for the identification of Fall Armyworm and its damage on maize as well as cassava mosaic disease, cassava brown streak disease and damage caused by cassava green mite. NURU is a mobile phone app (in Android smart phones) that is currently available on Google Play as ‘PlantVillage NURU’ or just ‘NURU’. The app uses an AI system for detection and identification of disease symptoms or pests and shows the user the symptoms, damage or pests it has identified. In addition, NURU gives advice on practices for managing the pests and diseases it has identified; both the diagnosis and advice are given on realtime. NURU was developed using machine learning with an AI system developed for both object and pattern recognition to differentiate images of healthy and damaged/diseased leaves. For diagnosis of cassava diseases, NURU was trained using 2,756 images of healthy and symptomatic leaves that were collected and annotated by experts in cassava pests and diseases from IITA in Tanzania. Field tests showed that NURU could diagnose healthy plants with an accuracy rate of 88% while the accuracy for detecting disease symptoms on symptomatic plants was 100% for CMD-infected plants, 78% for CBSD-infected plants and 60% for plants with CGM damage. Ongoing work is being done to improve the accuracy of NURU in diagnosing the cassava diseases and to make it a simple and easy-to-use diagnosis and learning tool. Furthermore, NURU is being expanded to other plant diseases affecting banana, potato, sweet potato and yam.

Using simulation modelling to inform best management practice for the introduction of whitefly-resistant Cassava varieties Author: Hazel Parry Co-authors: Andrew Kalyebi, Sarina Macfadyen Cultivation of whitefly-resistant varieties of Cassava has lagged the cultivation of disease-resistant varieties, and is a “valuable, but still underexploited” opportunity1. Breeding for so-called Host Plant Resistance (HPR) to pests has great potential as a low-cost, sustainable solution to help manage pest and disease problems in poor farming regions such as sub-saharan Africa (SSA), where resources are limited across a long growing cycle2, 3. However, in order to successfully develop or introduce a new variety to suppress an insect pest in an agricultural system, an understanding of the potential efficacy of that new variety in the context of existing management practices would be highly valuable. Simulation modelling across a range of resistance mechanisms and crop management scenarios is a presented here as a novel means to enable this understanding to be developed.

An overview of Bemisia tabaci (Gennadius) MEAM1 (silverleaf whitefly) management in Australian cotton: past, present and future Author: Richard Sequeira Co-authors: Tanya Smith, Simone Heimoana, Lewis Wilson The silverleaf whitefly (SLW) exploded onto the Australian cotton pest management radar following an outbreak in 2001 centred on the cotton growing area around the town of Emerald in central Queensland (CQ). Since then, SLW has become a key pest of cotton in the southern cotton growing regions of Australia – the Macintyre, Gwydir and Namoi valleys. The outbreak of SLW in 2001 was the trigger for the development of sampling protocols and a decision support system based on dynamic population density thresholds that has underpinned effective whitefly management in CQ cotton since its introduction in 2006. Feedback from southern cotton growers and crop managers in recent years has highlighted the growing perception that current sampling and management recommendations for SLW, based primarily on research done in CQ, give inconsistent results across different cotton growing areas within and among seasons. Research done by CSIRO cotton scientists in Narrabri from 2015 – 2018 has vindicated industry feedback on the variable efficacy of the contemporary sampling guidelines and thresholds as the basis of spray decisions in southern cotton growing areas. The CSIRO research shows that variable sampling outcomes are consistent with variable behavioural responses of SLW to environmental drivers (temperature, humidity), the evolution of larger, denser crop canopies in high yielding crops, and possibly the interaction of whitefly management with spray practices aimed at controlling other major sucking pests of cotton, e.g. Creontiades spp. (mirids). The Australian cotton industry is at a cross roads from a pest management perspective. Cotton growers are now routinely achieving yields of 15-16 bales (ha-1). Such high yielding crops can sustain less insect pest damage than ever before. At the same time, pest management in cotton has also become more complex than even before with the recent (2010) addition of Phenacoccus solenopsis (cotton mealybug) to the traditional cotton pest spectrum, viz. SLW, mirids, Aphis gossypii (cotton aphid), mites and thrips. A consequence of sole reliance on chemical pesticides for insect pest control in Australian cotton is that crop managers are increasingly required to tread a fine line between controlling one pest and flaring others. The challenge for Australian cotton growers now and into the future is to embed key pests such as mirids, SLW and cotton mealybug into multifaceted IPM strategies. On-going and future SLW research will be focussed on developing reliable and effective sampling protocols for adults and nymphs in SQ and northern NSW.

Managing Whitefly, Bemisia Tabaci Through Implementation of Integrated Pest Management In Indian Punjab Author: Vijay Kumar Co-authors: PK Chhuneja, SK Kataria, Gurmail Singh, Jagdish Arora, Mandeep Pathania, Vikas Jindal, HS Bhullar, Paramjit Singh Cotton (Gossypium spp.) is an important cash crop of India. One of the major bottlenecks in cotton cultivation is biotic stresses due to attack of insect pests and diseases. Bt cotton provides protection against lepidopteran pests mainly bollworms but it does not provide resistance against sucking insect pests. Among the sucking pests, whitefly, Bemisia tabaci (Gennadius) appeared in epidemic form in Indian Punjab during 2015. As a result, the crop productivity in Punjab fell substantially from 574 kg/ha of lint in 2014-15 to only 197 kg/ha in 2015-16. The major reason for higher incidence of whitefly were favourable climatic conditions, delayed sowing, survival on alternate hosts, use of mixture of unrecommended and sporious insecticides, development of resistance and resurgence to some conventional insecticides, faulty spray technology etc. For effective management of whitefly, Integrated Pest Management strategy was implemented in Punjab. It includes regular surveillance of whitefly on alternate hosts (brinjal and cucurbits) from February

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Oral Abstracts and on cotton from April onwards, removal of weeds during MarchMay to prevent the carryover of whitefly, availability and quality inputs, ensuring canal water availability for timely sowing, use of non-chemical approaches like traps, neem based botanicals, chemical insecticides based on economic threshold level, proper spray methodology. New insecticides like pyriproxyfen, flonicamid and dinotefuran with different mode of action were evaluated and recommended. Resistance and resurgence in whitefly was recorded against fenvalrate, cypermethrin, imidaclorid, acephate, fipronil and accordingly farmers were cautioned not to use these insecticides. Literature pertaining to whitefly management were distributed to cotton growers at their doorstep. During the season, midcourse modifications were also made based on feedbacks from the field. After implementation of developed IPM strategy during 2016 and 2017, the incidence of whitefly was monitored at weekly interval in cotton belt of Punjab. The data revealed higher incidence of whitefly (22-42 adults/ leaf) in 2015, whereas in 2016 and 2017, whitefly appeared early in the season and remained comparatively low throughout the season. Judicious use of pesticides by farmers during 2016, a huge quantity of pesticide worth Rs 54.42 crore (Rs 2162 per ha) was saved. With the joint efforts of scientists, State Department of Agriculture and farmers, whitefly was managed successfully during 2016 and 2017 resulting all time the highest productivity of 756 and 730 kg/ha lint, respectively.

Automated whitefly counting – an evaluation of 3 methods Author: Ernest Mwebaze Co-authors: Solomon Nsumba A key phenotype for breeders and entomologists is the count of adult whiteflies resident on cassava leaves in the field. This task is presently a very tedious manual process involving the actual physical count of these whiteflies in the fields. Small improvements has been realized with the use of tally counters in the field. In this work we propose three automated systems for counting whiteflies; a mobile application for in-field count, a web and desktop version for out-of-field count. We show that from the initial 86% accuracy of the whitefly count application we can increase recall and precision by small adjustments in the automated whitefly count pipeline. We also provide a solid evaluation of the different systems and provide recommendations about the different use cases for the three applications.

Resistance to insecticides of MEAM1 and IO whitefly species (Hemiptera: Aleyrodidae) in La Réunion Author: Alizee Taquet Co-authors: Helene Delatte, Martial Grondin, Aela Vancassel, Benoit Barres, Helene Jourdan The generalization of the use of pesticides in pest management programmes has led to the emergence and rapid evolution of resistance in pest populations, threatening crop yield and quality and rendering long-term control difficult. Bemisia tabaci (Gennadius) is a major pest distributed worldwide and composed of more than thirty cryptic species. Three whitefly species coexist in La Rèunion, an island in the southwest Indian Ocean, two of which are widespread. The indigenous IO species and the invasive MEAM1 species, can be found preferentially on weeds and crops, respectively. In other countries, MEAM1 has already demonstrated high resistance levels to all of the important classes of insecticides commonly used to control those populations. To assess the resistance status of these two species in La Rèunion, fifteen populations were collected all over the island from greenhouses, open fields, borders of cultivated sites and from natural areas. Three main classes of pesticides were tested in leaf-dip bioassays using formulated acetamiprid (Supreme 20 SG, 200 g.kg-1), pymetrozine (Plenum 50 WG, 500 g.kg-1) and deltamethrin (Decis Protech, 15 g.L-1), which belongs to Neonicotinoid, Pyridine azomethine derivatives and Pyrethroid, respectively. The resistance ratios (RRs) of the sampled populations were calculated relative to a known susceptible laboratory strain. The susceptibility to acetamiprid varied among the collected MEAM1 populations (RRs: 3,3-147).

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The MEAM1 species displays evidence of high resistance to both deltamethrin (LC50 > 3,25 ml.L-1) and pymetrozine (LC50 > 10000 mg.L). Differences in LC50 observed between MEAM1 and IO laboratory strains were less than 3-fold for both pymetrozine and acetamiprid, but more than 550-fold for deltamethrin meaning that this IO population is more susceptible to this pyrethroid. Our results are in line with loss of efficacy reported in the field for acetamiprid and pymetrozine. Moreover, it echoes the distribution of IO and MEAM1, the former being in non-treated areas, the later in greenhouses and open fields. Our results are finally discussed with regard to their impact on farming practices in La Rèunion. 1

Threats to vegetable production from whiteflytransmitted viruses in the southeastern United States: Insights into whitefly-virus interactions and epidemics Author: Rajagopalbabu Srinivasan Co-authors: Kiran Gadhave, Saurabh Gautam, Saioa Legarrea, Bhabesh Dutta, Timothy Coolong, William Turechek, Scott Adkins The southeastern United States including Georgia, South Carolina, and Florida is a major producer of important vegetables such as beans, cucurbits, and tomato. Currently, these vegetables are being threatened by whiteflies (Bemisia tabaci Biotype B) and whiteflytransmitted DNA and RNA viruses including Tomato yellow leaf curl virus (TYLCV, Genus Begomovirus family Geminiviridae) and Tomato chlorosis virus (ToCV, Genus Crinivirus, Family Closteroviridae) in tomato; and Cucurbit leaf crumple virus (CuLCrV, Begomovirus), Cucurbit yellow stunting disorder virus (Genus Crinivirus), and Squash vein yellowing virus (Genus Ipomovirus; Family Potyviridae) in cantaloupe, cucumbers, pumpkin, squash, and watermelon. CuLCrV also severely affects snap beans. These viruses are phloem restricted in hosts and transmitted by whiteflies in a persistent or semi-persistent manner. TYLCV has been a chronic feature in this area since the mid-1990s; the other viruses were introduced subsequently. The cropping pattern in the region favours the temporal overlap of viruses. Absence of nonfeeding modes of transmission and identification of alternate hosts suggests that the viruses have become endemic to the region, and virus epidemics are becoming routine. Much of the knowledge on whitefly-virus interactions arises from the tomato-TYLCV pathosystem. Our team has been involved in evaluating whitefly fitness following virus infection, and how these variables influence host resistance to TYLCV. Typically, TYLCV infection positively influenced whitefly host preference and development. However, these effects were only realized with the virus-susceptible genotype. Absolute PCR-based quantitation revealed that resistant genotypes accumulated less virus than susceptible genotypes and remained less attractive to vectors. Also, whiteflies acquired less virus from resistant than susceptible genotypes. These results suggested that resistant genotypes could contribute to the overall reduction of virus inoculum in the agroecosystem. Mixed viral infections and synergistic interactions in plant hosts are common, and consequently virus-vector interactions could be altered. Mixed infections in whiteflies following acquisition from multiple crops, and mixed viral infections in individual crop hosts and their effects on whitefly fitness and virus transmission are being examined in depth. Results thus far indicate that the virus source, mixed virus infection in hosts, and acquisition sequence could all influence virus acquisition and transmission by vectors as well as vector fitness. The complexity of these intertwined whitefly-host-virus interactions have made prediction and management of virus epidemics difficult. Development of area-wide and novel management strategies is becoming critical to promote sustainable vegetable production because this problem shows no signs of abating.



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Poster Presentation Table Poster

Presenters Name

Paper Title

Theme

1

Jing Bai

Transcriptome responses to the thermal stress and expression pattern analysis of HSP70 in Bemisia tabaci

Biology, Ecology and Invasion Biology

2

Helene Jourdan

Fitness cost of insecticide resistance in Bemisia tabaci from Reunion Island

Management Control and IPM

3

Everlyn Wosula

Exploring the potential of KASP genotyping and PCR-RFLPs in diagnosis of cassava-colonizing Bemisia tabaci

Systematics and Evolution

4

Helene Delatte

Bemisia tabaci species diversity colonizing cassava associated to the severe CBSD epidemic in the Comoros archipelago

Systematics and Evolution

5

Laura Boykin

Transcriptome analysis reveals an amino acids deletion in the GroEL chaperonin gene of Hamiltonella from native Bemisia tabaci populations

Whitefly Endosymbionts

6

Renate Krause-Skate

Behavior of Bemisia tabaci Mediterranean and Middle East Asia Minor I species on soybean

Whitefly Plant interactions

7

Renate Krause-Skate

Influence of Tomato severe rugose virus in the performance of MEAM1 and MED Bemisia tabaci species

Whitefly Virus interactions

Poster Abstracts Transcriptome responses to the thermal stress and expression pattern analysis of HSP70 in Bemisia tabaci Author: Jing Bai Co-authors: Xiao-Na Liu, Ming-Xing Lu, Yu-Zhou Du In the global climate warming environment, changed temperature not only threaten agricultural production, but also they affect individual biological behavior, popular and community of many insects, and consequently reduce the stability of our ecosystem. But it is a complex adaptive process of insect’s ability to respond to temperature stress, so we need some advanced research technology to figure out the process. At present, the transcriptome sequencing technology has been widely used in insect research. Through this technology, we microscopically understand the ability of insects to adapt to temperature stresses. Bemisia tabaci as a species complex containing at least 36 cryptic species, is a kind of important agricultural pests. It have widely distributed in more than 100 countries and regions as a very invasive pest because this pest has a strong ability to adapt to various environments. It caused the great losses of agricultural production. In this paper, transcriptional technology was used to check transcriptional profiles of MED cryptic species B. tabaci under cold temperature stress (-10 degree Celsius) and heat temperature stress (43 degree Celsius). It was showed that 3024 unigenes were significant difference expressed under cold-stress and 39 KEGG enrichment pathways were annotated. 4437 unigenes were found significant difference expressed under heat-stress and 18 KEGG enrichment pathways were annotated. What’s more, It was found 11 gene fragments of heat shock protein 70 (HSP70) in B.tabaci among the significant difference expressed associated genes under the temperature. Quantitative RT-PCR was used to identify the relative expression level of the 11 HSP70 gene fragments, and it was found that the results were consistented with results that measured by transcriptome. The expression levels of 11 HSP70 gene fragments which were found in transcriptome under heat temperature stress were significantly different from the control (26 degree Celsius). In conclusion, it was found that HSP70 plays an important role in the stress tolerance of B. tabaci through transcriptome analysis, especially under heat-stress.

Fitness cost of insecticide resistance in Bemisia tabaci from Reunion Island Author: Helene Jourdan Co-authors: Aela Vancassel, Alizee Taquet, Martial Grondin, Helene Delatte Bemisia tabaci is a major agricultural pest, with a worldwide distribution, causing serious damage to host plants mostly through the transmission of many plant viruses. It is a complex of morphologically indistinguishable species. Pest management of this species complex is mainly based on selective insecticides but this method may be hindered by the evolution of insecticide resistance. Alternation of diverse chemical classes of insecticides is a way to avoid the appearance of resistance. This method is based on the assumption that resistance carries a cost in the absence of insecticide. We tested this assumption on 7 field populations (with low genetic differentiation) and one laboratory population of MEAM1 whitefly species. Those 8 populations showed contrasted levels of resistance to acetamiprid (Supreme 20 SG, 200 g/kg) with resistance ratios ranging from 1 (equivalent to a concentration of 3.42 mg/L for the laboratory population) to 90. In each population, we measured 4 fitness-related traits: female survival, lifetime reproductive success, hatching rate and adult emergence percentage. We found no correlation between measured traits and acetamiprid resistance, indicating a lack of fitness cost. These results were confirmed by a simulation approach based on our experimental dataset. However, we found significant differences between populations in survival, lifetime reproductive success and hatching rate indicating potential local adaptations. The failure to detect resistance cost may either reflect experimental limitations or reveal a potential compensatory evolution that had attenuated fitness cost through time and favored the spread of insecticide resistance.

Keywords: Bemisia tabaci, Transcriptome, Temperature stress, Associated genes, Heat shock protein 70, Expression

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Poster Abstracts Exploring the potential of KASP genotyping and PCR-RFLPs in diagnosis of cassava-colonizing Bemisia tabaci Author: Everlyne N. Wosula Co-authors: Wenbo Chen, Zhangjun Fei, James P. Legg In view of the global importance of Bemisia tabaci coupled with its taxonomic complexity, it is essential to have methods for rapid and accurate genotyping. A recent study using SNP-genotyping demonstrated that mtCOI sequencing can be an unreliable method for distinguishing the major genetic groups of cassava-colonizing whiteflies. The objective of this study was to explore the potential of using SNP-based PCR-RFLPs and Kompetitive Allele Specific PCR (KASP) as robust tools for the rapid diagnosis of cassavacolonizing whiteflies. SNPs that distinguish the recently designated six populations of cassava whiteflies (SSA-ECA, SSA-ESA, SSA-CA, SSA-WA, SSA2 and SSA4) were identified from six separate scaffolds (introns and intergenic regions) of the SSA-ECA genome. Primers were designed to amplify ~500 – 900bp genome portions containing the SNPs which were sequenced to determine their effectiveness at distinguishing cassava whiteflies compared to mtCOI sequencing. The six SNP-based PCR amplicons were subjected to RFLP analysis using restriction enzymes targeted to cut at SNP positions. Six SNPbased primers were also designed (LGC Genomics, UK) to explore the use of a KASP assay in cassava whitefly diagnosis. Preliminary results indicate that sequencing of the six SNP-based amplicons consistently distinguishes the six populations, while RFLP and KASP assays are generally consistent in distinguishing the six populations. Further work is being undertaken to optimize these assays for rapid diagnosis of cassava whiteflies. Proper identification of cassava whitefly cryptic species is critical for the development of effective management strategies.

Bemisia tabaci species diversity colonizing cassava associated to the severe CBSD epidemic in the Comoros archipelago Author: Benoit Jobart Co-authors: Christophe Simiand, Hadija Ally, Issa Mze Hassani, Maruthi Gowda, Helene Jourdan, Helene Delatte Cassava brown streak disease (CBSD) is considered as one of the most important viral disease of cassava in Africa and is a major threat to food security. The expanding CBSD epidemic in East and Central Africa is caused by two ipomoviruses: Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV) which are both vectored by whiteflies of the Bemisia tabaci species complex. Superabundant populations of the B. tabaci SSA1 species were recently linked to the increase and spread of those viruses in Africa. In 2014, symptoms of yellowing on leaves and brown necrotic rot on roots on different cassava landraces of Mayotte, an island situated East of Tanzania in the Comoros archipelago, were associated with CBSV and UCBSV. Two years later, both of those viruses were isolated from similar symptoms on the three other islands of the Comoros archipelago: Grande Comore, Anjouan and Mohèli. Fields with those viral symptoms were also reported with high whitefly abundances. In 2017, a survey on the four islands was conducted to evaluate the viral incidence (CMD/CBSD) together with whiteflies abundances, and to determine the species diversity on cassava and associated crops. Molecular analyses were conducted on whiteflies using part of the mtCOI for species identification and microsatellite markers were analyzed for detecting population structuring between the four islands. B. tabaci adult individuals were collected from 52 representative locations on the four Comoros islands, among which several species were observed. Phylogenetic analyses allowed to determine 7 different genetic groups, that were associated to SSA1 (-SG2, -SG3), MED, Indian Ocean (IO), Bemisia afer, and three other groups of species distinct from any of the other species described so far (>4% of nucleotide identity). Sequences of the SSA1-SG2 were very close (99% nucleotide identity) to the ones of East Africa. This species was found as the dominant one on cassava and associated to high visual abundances (20 to 500 whiteflies / plant) in the sampled fields. Nuclear analyses were not able to differentiate populations between islands within SSA1-SG2 individuals. These results suggest a recent invasion in the Comoros archipelago from East Africa which

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might have triggered the expansion of the epidemic of CBSD. Cassava is an important staple food in the Comoros archipelago and in the closest continental island of Madagascar; those results are of great significance for managing cassava in this region and needs urgent attention to prevent further spread into Madagascar.

Transcriptome analysis reveals an amino acids deletion in the GroEL chaperonin gene of Hamiltonella from native Bemisia tabaci populations Author: Bruno Rossitto De Marchi Co-authors: Tonny Kinene, James Mbora Wainaina, Renate KrauseSakate, Laura Marie Boykin The whitefly, Bemisia tabaci, is a species complex of more than 40 cryptic species and a major agricultural pest. It causes extensive damage to plants mainly by transmitting plant viruses. The complexity of B. tabaci might also depend on the inherited bacterial endosymbionts whose functions are not fully understood. Among the facultative symbionts, Hamiltonella defensa is a maternally transmitted gamma-proteobacterium found sporadically in sap-feeding insects, including aphids, psyllids, and whiteflies. The GroEL proteins encoded by Hamiltonella has been found interacting with the coat protein of begomovirus and therefore facilitating virus transmission. Understanding the genetic and transcriptomic composition of these insect pests, the viruses they transmit and the microbiota is crucial to sustainable solutions for farmers to control whiteflies. Illumina RNASeq was used to obtain the transcriptome of individual whiteflies from six different populations from Brazil including Middle East-Asia Minor 1 (MEAM1), Mediterranean (MED) and New World 2 (NW2). Raw reads were assembled using CLC Genomics Workbench and subsequently mapped to a reference GroEL chaperonin gene (CP016303) from GenBank. Nucleotide sequences of the complete GroEL chaperonin gene from the facultative bacterial endosymbiont Hamiltonella were obtained for 6 different populations for further analysis in Geneious v9.1.8 software. In addition, primers were designed (GroEL 1,354 ForCCTC TGCG TCAG ATTG TGGT and GroEL 1,663 Rev – TCAT ACCA TTCA TTCC GCCC A) for a PCR reaction (95°C for 5min, 35 cycles at 95°C for 30 secs, 59.5°C for 30 secs, 72°C for 30 secs and 72°C for 10 min) followed by nucleotide sequencing to confirm the results obtained by NGS. Analysis of the translated proteins revealed a three amino acids deletion present only in Hamiltonella from the B. tabaci NW2 species among whiteflies populations analysed. The deletion was a sequence of two glycine and one isoleucine. The genomic data obtained in this study will aid for better understanding the functions that Hamiltonella may have in whitefly biology and serve as a reference for further studies regarding whiteflies in Brazil.

Behavior of Bemisia tabaci Mediterranean and Middle East Asia Minor I species on soybean Author: Luis Fernando Maranho Watanabe Co-authors: Vinicius Henrique Bello, Bruno Rossitto De Marchi, Marcelo Agenor Pavan, Renate Krause-Sakate Soybean is one of the most important crops cultivated in Brazil and generate millions of dollars to the country. It is affected by the direct feeding damage caused by the predominant species of whitefly Bemisia tabaci (Gennadius) Middle East-Asia Minor 1 (MEAM1), widespread around the country. This insect also transmits the carlavirus Cowpea mild mottle virus (CpMMV) and the begomovirus Bean golden mosaic virus (BGMV) to them, being the first one an emergent disease in Brazil. Since 2014, the Mediterranean (MED) species was reported in the South of Brazil and now it is spreading to different states imposing new concerns to the low susceptibility to insecticides used in agriculture. In this study, we investigated the competitive displacement and performance between MED and MEAM1 species on soybean. Until the fifth generation (150 days), the percentage of insects of each species was 50% suggesting that both species are equally competitive on soybean. We observed that there is no significant difference in number of eggs laid, egg hatched rate, adults emergence and the survival rate between both species. However, MEAM1 adults start to emerge five days earlier than MED



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General Information adults and the development time of MEAM1 is faster than that of MED (25 vs 28 days, respectively). We conclude that the recently introduced B. tabaci Mediterranean species is well adapted to soybean and may impose problems to this culture. Monitoring the insect is important to indicate the best control measures.

Influence of Tomato severe rugose virus in the performance of MEAM1 and MED Bemisia tabaci species Author: Vinicius Henrique Bello Co-authors: Luis Fernando Maranho Watanabe, Bruno Rossitto De Marchi, Lucas Machado Fusco, Marcelo Agenor Pavan, Renate Krause-Sakate The whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodiade) is an important pest and responsible for plant viruses outbreaks. The Middle East-Asia Minor 1 (MEAM1, formerly B biotype) and Mediterranean (MED, formerly Q biotype) are the most important and have attained global status. In Brazil, MEAM1 was reported in the 90’s and is widespread across the country; meanwhile, MED was recently reported in the South and Southeast regions. Both species transmit the predominant tomato begomovirus in Brazil, Tomato severe rugose virus (ToSRV). So we evaluated the performance of MEAM1 and MED on healthy and ToSRV-infected tomato plants. MEAM1 presented a higher egg hatch rate and number of adults emerged compared to MED in all experiments tested. Both MEAM1 and MED decreased in number of eggs, eggs hatch rate and number of adults emerged when feeding on ToSRV-infected plants. On infected ToSRV plants, all the adults’ emergence was concentrated during three days, however on healthy plants it was distributed during 10 days. For MED the emergence on infected ToSRV plants was delayed in 10 days compared to healthy plants, indicating a negative effect of the virus on the insect life cycle. Aviruliferous B. tabaci MED insects prefer to settle on healthy than on ToSRV-infected plants, while viruliferous have preference to settle on infected plants during the 6 to 96 hours evaluated. Aviruliferous MEAM1 insects does not have preference to settle on ToSRV-infected or healthy plants. However, viruliferous MEAM1 prefers to settle on ToSRV-infected plants. All these results can help for better understanding the epidemiology of ToSRV in tomato and the B. tabaci species present in the area.

Registration Desk & Check In The registration desk is located in the Southern Cross Foyer of the Esplanade Hotel Fremantle by Rydges. The desk will operate during the times below: Sunday 16 September 2018

16:00 – 18:30

Monday 17 September 2018

8:00 – 16:00

Tuesday 18 September 2018

8:00 – 16:30

Wednesday 19 September 2018

8:00 – 16:00

Program Information Speakers please bring your presentation on a USB to upload with the AV Technician in the room on the day of your presentation. Posters will be hung in the foyer on a poster board. Please bring your poster with you and you will be allocated a board at the registration desk.

Symposium BBQ Dinner Date: Wednesday 19 September 2018 Time: 1830 – 2200 Location: Resort Pool of the Esplanade Hotel Fremantle by Rydges A BBQ Dinner will be provided. A cash bar is available for drinks.

Alternative Transport SmartRider A SmartRider allows you to travel on all TransPerth bus and train services. You can purchase your go card at the following locations: – The Whistle Stop – Shepherds Newsagency

Free Transport Hail a CAT bus for free in Fremantle. The Blue CAT and Red CAT bus services circle the city every 10 – 15 minutes and stop at destinations in Fremantle and South Fremantle from 7:30 to 20:00 weekdays.

Taxis Taxi ranks are available at the Esplanade Hotel Fremantle by Rydges, as well as throughout The. Contact Black & White Cabs on 133 222 and Swan Taxi 13 13 30.

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