Research Article SEASONAL ABUNDANCE OF ...

International Journal of Agriculture Sciences ISSN: 0975-3710&E-ISSN: 0975-9107, Volume 9, Issue 5, 2017, pp.-3759-3762. Available online at http://www.bioinfopublication.org/jouarchive.php?opt=&jouid=BPJ0000217

Research Article SEASONAL ABUNDANCE OF WHITEFLY Bemisia tabaci (GENNADIUS) ON BT COTTON IN RELATION TO METEOROLOGICAL PARAMETERS UNDER HARYANA CONDITION MEHRA SWATI* AND ROLANIA KRISHNA Department of Entomology, CCS Haryana Agricultural University, Hisar, 125 004, Haryana, India *Corresponding Author: [email protected] Received: January 11, 2017; Revised: January 13, 2017; Accepted: January 15, 2017; Published: January 30, 2017 Abstract- The present studies on population dynamics of whitefly, Bemisia tabaci (Gennadius) on cotton hybrid BIO 6588 (BG II) were carried out during Kharif 2014 at Cotton Research Area, CCS Haryana Agricultural University, Hisar. Two peaks of whitefly adults were recorded from 34 th and 38th Standard Meteorological Week (i.e. 3rd week of August and 3rd week of September, 2014) with number as high as 37.94 and 45.42 adults per leaf whereas nymphal population was as high as 45.26 and 62.93 nymphs per leaf during 33th and 39th SMW (i.e. 2nd week of August and last week of September). Whitefly adult population showed significant positive correlation with morning relative humidity (r=0.455) and sunshine hours (r=0.650). Sunshine hours also showed significant positive correlation (r=0.543) with the nymphal population. Keywords-Bemisia tabaci, Btcotton, population dynamics, weather factors. Citation: Mehra Swati and Rolania Krishna (2017) Seasonal Abundance of Whitefly Bemisia tabaci (Gennadius) on Bt Cotton in Relation to Meteorological Parameters Under Haryana Condition. International Journal of Agriculture Sciences, ISSN: 0975-3710 & E-ISSN: 0975-9107, Volume 9, Issue 5, pp.-3759-3762. Copyright: Copyright©2017 Mehra Swati and Rolania Krishna. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited. Academic Editor / Reviewer: Satbeer Singh Introduction Cotton crop has a global significance as it is commercially cultivated on large scale for fibre purpose and also known as “White gold”. In India, more than 60 million people are engaged in cultivation, processing, marketing and other cotton related activities. Area wise, India ranks first in world (11.97 million hectares), whereas, it ranks second in production (34.10 million bales) next to China. Total area under cotton crop in Haryana is 6,14,000 hectares and total production is 2.5 million bales [1]. Bt cotton is infested by a number of sucking insects including the whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), which is one of the most notorious pests in tropical and subtropical agriculture. The pest is quite devastating on cotton, brinjal, okra, tomato and several ornamental plants [2]. Both nymphs and adults cause direct damage by piercing and sucking of sap from the foliage of plants. Direct damage includes feeding on the leaves resulting into leaf chlorosis, leaf withering and premature dropping of leaves that eventually leads to plant death. Indirect damage results in the accumulation of honeydew produced by the whiteflies, which serves as a substrate for growth of black sooty mould on leaves and bolls. The mould reduces photosynthesis and lessens the value of the plant or yields rendering them unmarketable [3]. B. tabaci is considered the most common and important vector of plant viruses worldwide and transmits plant viruses in seven distinct virus groups including geminiviruses, oviruses, carlaviruses, potyviruses, nepoviruses, loteoviruses and DNA-containing rod-shaped viruses [4]. Several workers have attributed outbreaks of this pest due to favourable weather parameters i.e. temperature, relative humidity and precipitation that plays a major role for the multiplication and development of whitefly [5-8]. A combination of 27°C temperature and 72 per cent relative humidity appears to be highly conducive for population buildup of this pest [9]. Outbreaks of this pest were reported in Southern parts of India during 1985-87 and in Northern parts during 1987-95 on cotton, tobacco, okra, eggplant and several ornamental plants [2]. Whitefly has been on a song in north India, three

years in a row, especially in Punjab, Haryana and Rajasthan [10]. However, detailed studies on the influence of abiotic and biotic factors on the incidence of whitefly on cotton under the agro-climatic conditions of Haryana, particularly on Bt cotton which is generally more susceptible to sucking pests are lacking [8]. It is needed to sort out the precise nature or extent of relationship, which exists between whitefly population and weather factors to determine pest status and to formulate effective pest control strategies for sustainable management of this pest. Hence, the present study was focused on location specific seasonal occurrence of whitefly on cotton crop and its relation with weather parameters. Materials and Methods Studies on population dynamics of whitefly, Bemisia tabaci (Gennadius) on the cotton crop were carried out during kharif 2014 at Cotton Research Area, Department of Genetics and Plant Breeding, CCS Haryana Agricultural University, Hisar (29º 10' N lattitude and 75º 43' E longitude at 215m above mean sea level). Transgenic cotton hybrid BIO-6588 BG II was sown during May, 2014 in an area of 500 m2 following recommended package and practices of to conduct population dynamics studies. The crop was kept unsprayed for the pest buildup. The observations on whitefly adults and nymphs were recorded at weekly intervals throughout the crop season starting from the last week of June. Whitefly adult population was recorded during June to October (started after one month of sowing) by observing undersides of three fully formed leaves from the upper canopy of each 25 randomly selected plants from the plot. The whitefly adult population was averaged and expressed as number of adults/leaf. Nymphal population was observed from underside of the leaf surface from three fully formed leaves of middle canopy of each 25 randomly selected plants. The nymphal population of whitefly was counted by using the hand lens of 10X zoom. The above observations (adult and nymphs) were recorded before 9:00 A.M. The nymphal population was averaged and expressed as the number of nymphs/leaf.

International Journal of Agriculture Sciences ISSN: 0975-3710&E-ISSN: 0975-9107, Volume 9, Issue 5, 2017 || Bioinfo Publications ||

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Seasonal Abundance of Whitefly Bemisia tabaci (Gennadius) on Bt Cotton in Relation to Meteorological Parameters Under Haryana Condition Statistical Analysis: The averaged data of population dynamics of whitefly nymphs and adults were subjected to correlation and multiple regression analysis with weather parameters (maximum and minimum temperature, morning and evening relative humidity, wind speed, sunshine hours and rainfall)at different Standard Meteorological Weeks (SWM). The data were at the 5 per cent level of significance. Results and Discussion Population dynamics of B. tabaci adults Studies revealed that whitefly, Bemisia tabaci remained active on the cotton crop throughout the cropping period [Fig-1] and [Table-1]. The pest was initially noticed

on the crop during last week of June (26 th SMW) with a population density of 2 adults per leaf. The population of the insects increased with the advancement of crop growth. There were two closer peaks of whitefly adult population. First peak was recorded during 34th SMW and second in 38th SMW (i.e. 3rd week of August and 3rd week of September) with number as high as 37.94 and 45.42 adults per leaf, respectively. In line with the findings, different workers have reported 1 to 2 peaks of whitefly adult population on different cotton genotypes [11, 12]. Maximum population of whitefly adults was observed when the temperature ranged from 36.2°C (Tmax) to 22.9°C (Tmin), relative humidity ranged from 77.4 per cent (RHm) to 39.3 per cent (RHe), sunshine hours (10 hrs.) and wind speed 5.5 km/h.

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.

25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

0 1 4 18.37 16.2 30.89 27.28 35.6 45.26 42.82 40.2 21.48 17.1 49.57 62.93 37.69 26.57 19.33 12.21

Tmin

RHm

RHe

40.5 38.0 38.0 38.5 38.5 37.6 35.6 35.2 36.1 38.5 35.3 33.0 34.4 36.2 36.0 37.0 34.6 29.8 32.4

27.3 26.3 27.6 28.2 27.8 27.7 26.9 26.8 26.5 25.8 25.5 25.5 24.7 22.9 21.6 21.7 18.9 15.3 19.0

66.3 68.5 64.7 63.7 66.5 69.5 91.2 83.3 78.3 70.0 84.4 91.9 89.4 77.4 74.1 76.3 79.7 89.7 85.3

38.0 43.5 43.5 42.5 50.3 52.0 64.2 54.7 48.1 37.4 60.9 66.7 59.0 39.3 37.6 31.6 38.6 38.0 47.1

8.6 7.1 6.9 6.9 7.7 7.5 5.7 4.4 9.1 5.9 6.5 8.7 4.7 5.5 6.1 4.4 5.2 2.4 3.5

Average temperature (°C)

Average relative humidity (%)

Average sunshine hours (hrs.)

0 2 4.68 9.61 13.25 18.78 21.9 24.98 33.46 37.94 34.26 24 21.69 45.42 35.42 29.2 31.44 29.45 16.22

Tmax

Average windspeed (km/h)

SMW

No. of whitefly nymphs/leaf

Sr. No.

No. of whitefly adults/leaf

Table-1 Population of whitefly adults and nymphs during different standard weeks during kharif 2014

7.3 6.5 5.2 4.8 4.7 3.8 6.5 5.3 8.6 10.4 6.3 5.4 7.0 10.0 9.9 9.5 9.0 8.0 7.0

Total rainfall (mm)

10.6 14.5 0.0 0.0 7.6 9.1 33.2 0.0 0.0 0.0 1.0 76.7 4.8 0.0 0.0 0.0 20.3 0.0 0.0

population. The population of whitefly nymphs was low during the initial periods of crop growth (i.e. 26th SMW to 27th SMW) [Fig-2] and [Table-1]. Two peaks of nymphal population were noticed throughout the cropping period. Nymphal population was as high as 45.26 and 62.93 nymphs per leaf during 33 rd and 39th SMW (i.e. 2nd week of August and last week of September), respectively. Maximum number of whitefly nymphs i.e. 62.93 per leaf was observed when temperature ranged from 36°C (Tmax) to 21.6°C (Tmin), relative humidity ranged from 74.1 per cent (RHm) to 37.6 per cent (RHe), windspeed 6.1 km/h and sunshine hours (9.9 hrs.).

Fig-1 Population of B. tabaci adults during different standard meteorological weeks The present findings are similar to the results of [13] who reported that a mean temperature of 32°C and lower relative humidity favoured the multiplication of B. tabaci in Punjab. A mean temperature of 30.3°C and mean relative humidity of 66.5 per cent resulted in maximum population of whitefly adults on urdbean crop [14]. Heavy rainfall and high temperature adversely affected the population of whitefly adults and resulted in reduction of the adult whiteflies population.Similar adverse effects of rain on whitefly population has been reported by several workers [12, 15, 16, 17]. Likewise, [18]reported that sunshine hours had significant positive influence on population of B. tabaci adults. Population dynamics of B. tabaci nymphs Similar trend was also observed in nymphal population as in case of whitefly adult

Fig-2 Population of B. tabaci nymphs during different standard meteorological weeks The present findings are in confirmation with [15] who reported that a mean


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Mehra Swati and Rolania Krishna temperature of 29.1°C and mean relative humidity of 65.8 per cent favoured the pest population on cotton crop. The population of whitefly nymphs declined with the occurrence of 76.7 mm rainfall during 36th SMW. Likewise, [15] reported that a mean temperature of 29.1°C and mean relative humidity of 65.8 per cent favoured the pest population on cotton crop.[12] reported negative influence of rainfall on the whitefly nymphal population. Non-significant but negative impact of rainfall on whitefly nymphal populations on cotton hybrid/variety (RCH-134 and H-1117) was reported by [15]. Likewise, [18 and 19]reported that sunshine hours had significant positive influence on B. tabaci nymphal population. Correlation of B. tabaci population with weather parameters The correlation analysis between different weather parameters and B. tabaci nymphs and adults presented in [Table-2] revealed that whitefly adult population had significant positive correlation with morning relative humidity (r=0.455) and sunshine hours (r=0.650). The results of [20, 21] support the present findings. They reported that whitefly population was positively correlated with morning relative humidity. All other remaining weather parameters like maximum and minimum temperatures, rainfall, wind speed and evening relative humidity had negative and non-significant correlation with adult B. tabaci population. Likewise, [16] reported negative correlation of maximum temperature (r= -0.524 to -0.561) and minimum temperature (r= -0.662 to -0.678) with whitefly population on Bt and non-Bt cotton hybrids. Similar negative effect of temperature on whitefly population was also reported by other workers [22-25]. Table-2 Correlation of B. tabaci population with weather parameters Weather parameters

Whitefly adults

Whitefly nymph

Maximum temperature (°C) Minimum temperature (°C) Morning RH (%) Evening RH (%) Windspeed (km/h) Total Rainfall (mm) Sunshine hours

-0.404 -0.428 0.455* -0.059 -0.312 -0.097 0.650*

-0.115 -0.161 0.181 -0.088 -0.090 -0.196 0.543*

Y= 142.40 – 5.38 Tmax + 2.22 Tmin – 1.31 RHm+ 1.23 RHe– 0.21 RF – 0.16 WS + 9.91 SSH

0.49

Conclusion: It is concluded from the study that pest density was quite high throughout the period of observation probably due to poor rains (< 200 mm) during whole monsoon season. Peak populations of whitefly adults were recorded from 34 th and 38th SMW with number as high as 37.94 and 45.42 adults per leaf whereas, nymphal population was as high as 45.26 and 62.93 nymphs per leaf during 33 th and 39th SMW. It is inferred from present study that increase in maximum and minimum temperature had adverse effect on population buildup of whitefly and on other hand any increase in morning relative humidity favoured the population buildup of B. tabaci. Abbreviations SMW: Standard Meteorological Week;Tmax: Maximum temperature; Tmin: Minimum temperature; RHm: Morning relative humidity; RHe: Evening relative humidity; 0C: degree Celsius. Author Contributions Both the authors equally contributed in the manuscript. Ethical Approval This article does not contain any studies with human participants or animals performed by any of the authors. Acknowledgements Authors are grateful to Dr. Ram Singh, Professor and Head, Department of Entomology, COA, CCSHAU, Hisar for providing necessary facilities to carry out the research work and his critical review of an earlier version of the manuscript. We also feel grateful to the other faculty members of Department of Entomology and Genetics & Plant Breeding for their needful help and comments.

*Significant at p=0.05 level of significance

Sunshine hours showed a significant positive correlation (r=0.543) with nymphal population. The present studies are in accordance with [19, 17] who reported that sunshine hours had significant positive influence on B. tabaci population. The correlation was negative and non-significant with all the remaining weather parameters like maximum and minimum temperatures, evening relative humidity, windspeed and rainfall except positive and non-significant correlation with morning relative humidity.Our results are in confirmation with the findings of [19, 24] who reported non-significant negative correlation of wind speed with whitefly population. Non-significant negative correlation of wind speed with whitefly adult and nymphal populations on cotton hybrid/variety (RCH-134, H-1117) was reported by [15]. Multiple regression analysis between weather factors and B. tabaci population The multiple regression analysis between abundance of B. tabaci nymphs and adults with weather parameters presented in the [Table-3] revealed that all weather parameters collectively accounted for 68 and 49 per cent variability in adult and nymphal populations, respectively. The present findings indicated that the influence of all the weather parameters was high and significant on whitefly adults (R2=0.68) and nymphal (R2=0.49) population. Similarly, [11] also reported high and significant (R2=0.60) influence of all weather parameters was on whiteflies population. The influence of all weather parameters was reported about 50 per cent in different cotton hybrids by [12,16]. Table-3 Multiple regression analysis between weather factors and B. tabaci population Whitefly adult

Whitefly nymph

Regression equation

R2

Y= 135.65 – 4.49 Tmax + 1.26 Tmin - 0.96 RHm + 0.94 RHe – 0.06 RF - 0.87 WS + 7.69 SSH

0.68

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