Hexamermis cathetospiculae n. sp. (Mermithidae: Nematoda), a ...

0 downloads 0 Views 325KB Size Report
Straits Settlements and Federated Ma- lay States No. 1. 5. Rao, V. P. 1966. Survey for natural enemies of pests of paddy. Report U.S. PL-480 Project Com-.
360 Journal of Nematology, Volume 17, No. 3, July 1985 8. Stone, A. R. 1983. T h r e e approaches to the status of a species complex, with a revision of some species of Globodera (Nematoda: Heteroderidae). Pp. 221-233 in A. R. Stone, H. M. Platt, and L. F. Khalil, eds. Concepts in nematode systematics. New York: Academic Press. 9. Szczygiel, A. 1966. Studies on the fauna and

population dynamics of nematodes occurring on strawberry plantations. EkologiaPolska Series A, 14: 651-709. 10. Viglierchio, D. R., and R. V. Schmitt. 1983. On the methodologyof nematode extraction from field samples: Comparison of methods for soil extraction.Journal of Nematology 15:450-454.

Journal of Nematology 17(3):360-363. 1985. © T h e Society of Nematologists 1985.

Hexamermis cathetospiculae n. sp. (Mermithidae: Nematoda), a Parasite of the Rice Stemborer, Tryporyza incertulas (Wlk.) (Pyralidae: Lepidoptera) in Malaysia GEORGE 0 . POINAR, J R . l AND P O O N - M I N C H A N G 2

Abstract: Hexamermis cathetospiculae n. sp. (Mermithidae: Nematoda), a parasite of the rice stemborer, Tryporyza incertulas (Wlk.), is described. This mermithid was observed to control the stemborer in Malaysia. It is distinguished from o t h e r members of the genus by the shape of the vagina, the nearly straight spicules, and the form of the amphids. Key words: biological control, mermithid nematode, taxonomy.

In 1980, the junior author found some mermithids parasitizing larvae of the rice stemborer, Tryporyza incertulas, while splitting open rice stems at Bumborg Lima in Malaysia. Earlier reports of mermithids attacking T. (Schoenbius)incertulas were made by Pagden (4), Nickel (3), and Rao (5); however, the mermithids were not identified. Examination of nematodes from Malaysian stemborers showed that the mermithid was new to science. It is described here. MATERIALS AND METHODS

Postparasitic juvenile nematodes that emerged from T. incertulas larvae were maintained in soil at 25 C for 3 weeks when they had molted to adults. T h e nematodes

Received for publication 29 October 1984. 1 Division of Entomology and Parasitology, University of California, Berkeley, CA 94720. 2 Malaysian Agricultural Research and Development Institute, Mardi, Bumlong Lima, Malaysia.

were killed in 60 C water, fixed in TAF, and processed to glycerin for taxonomic studies. T h e parasites were collected during July 1980 at Bumborg Lima, Kepala Batas, Seberang Perai in Malaysia. 8YSTEMATICS

T h e nematodes were discovered to be a new species of the genus Hexamervnis. In the quantitative portion of the following description, measurements are given in micrometers unless otherwise noted. T h e range of the character is given in parentheses following the mean value.

Hexamermis cathetospiculae n. sp. (Figs. 1-8) M e r m i t h i d a e Braun 1883, Hexamermis Steiner 1924 (emended by Rubtsov 1978) Description: Long white nematodes with an adult cuticle ranging from 17 to 24 #m thick; adult cuticle with distinct cross fibers; head attenuated; six head papillae, ---4

FIGS. 1--8. Hexamermis cathetospiculae n. sp. 1) Dorsal view of female head. 2) Lateral view of male head. 3) En face view of female. 4) Ventral view of male tail. 5) Lateral view of male tail. 6) Cross section t h r o u g h female at midbody. 7) Lateral view of vagina. 8) Lateral view of tail of postparasitic juvenile.

Hexamermis cathetospiculae n .

Chang

sp.:Poinar,

2 1

,

i

i !

@~"

,

)~:

i

0

1

d"

~:~..

,

128/~

,4,8

"

', ,~-@

' ', ~:!':i



p.) ~)

-

.i~'p ."4

; Bo

• "" . '-ii'!~

"



"

-A"~# ~ G,-',

O'-:,'gee Om

.

::r

e~"£££~@5 ; ' •

~', \',,

. ':"., •

~dJ

Ooe~-O

,'/ //

V , k~ to°~~ ,,/

\~', ~

"



'

.

• '

"

.':H

f

::>7 /

361

362 Journal of Nematology, Volume 17, No. 3, July 1985 distinct; m o u t h terminal; amphids urn gina (as found in Oesophagomermis Artyushaped, opening behind the lateral ce- khovsky) and have the amphids separated phalic papillae and separated from them; from the lateral cephalic papillae (as found amphidial opening circular to triangular; in Ovomermis Rubtsov). T h e postparasitic six hy.podermal cords; lateral cords large, juveniles of Hexamermis possess a distinct containing 4 - 5 rows of nuclei in cross sec- pointed tail appendage (in contrast to the tion; ventral cord containing a double row r o u n d e d tail of Agamermis Cobb, Steiner of nuclei, whereas nuclei not visible in the and Christie). Characters separating H. dorsal and subventral cords. cathetospiculae from previously described Females (n = 10): Length 8.3 (3.0-12.8) members of the genus are the curved cm; greatest width 458 (320-544); distance V-shaped or J-shaped vagina, the nearly from head to nerve ring 468 (441-504); straight spicules, and the shape of the amvulva 55% (45-65); vagina V or J shaped, phids. containing a heart-shaped, cuticular lined Hexamermis microamphidis Steiner (6), dechamber just inside the vulvar opening, scribed from the tea bug in Java, is similar vulvar lips absent; vulvar opening circular; to the present species. However, the spicvagina length 345 (289-441), diameter of ules of H. microamphidis are shorter than amphidial openings 1.6-3.2; a vestigial anal the body width at the cloaca, whereas in opening located 315 (226-536) from the H. cathetospiculae they are longer. tail tip; trophosome terminating 386 (327T h e most similar of the described Hex409) from the tail tip. amermis species to H. cathetospiculae is the Males (n = 4): Length 3.3 (3.0-3.7) cm; EuropeanH. brevis Hagmeier (1). T h e shape greatest width 288 (256-320); distance and location of the amphids are almost from head to nerve ring 411 (396-428); identical, and the shape of the spicules is spicules paired, separate, nearly straight, similar. However, the spicules of H. cathepointed at tips; spicule length 312 (289- tospiculae are longer than those ofH. brevis 334); tail length 227 (208-252); tail width and are greater than the body width at the at cloacal opening 236 (220-252); amphid- cloaca. Also, the preanal genital papillae of ial openings diameter 4-5; genital papillae H. brevis extend anteriorly along the entire in three broken (double) rows; lateral dou- length of the spicules, whereas in H. cathble rows containing 20-32 papillae each, etospiculae, the preanal genital papillae exextending anteriorly past the cloacal open- tend less than half the length of the spicing but only half the length of the spicules; ules. median double row of 20-25 papillae exT h e present species differs from Eurotending anteriorly almost to the lateral pa- pean species, H. incisura Kaiser (2), H. elonpillae; tail bluntly rounded. gata Kaiser (2), and H. lineata Kaiser (2) by Postparasitic juveniles (n = 20): Cuticle the shape and position of the amphids and thick, measuring 17-26 micrometers, with spicules. distinct cross-striations; tail terminus with DISCUSSION a small spike-like appendage; sheds two cuticles simultaneously to become an adult. T h e parasites were readily recovered Type host: Tryporyza (= Schoenobius ) incer- from host larvae collected in July after the tulas (= incerteUus) (Pyralidae: Lepidop- rice harvest. Most host larvae contained a tera). single parasite, but some contained several. Type locality: Bumborg Lima, Malaysia. T h e insect larvae died soon after the nemaType specimens: Holotype (male) and todes emerged. allotype (female) deposited at the DeT h e parasites molted in 2-3 weeks, but partment of Nematology, University of mating and oviposition was not observed. California, Davis, California. Paratypes deLITERATURE CITED posited in the collection of the senior author. 1. Hagmeier, A. 1912. Beitrage zur Kennmis der Diagnosis: T h e present species is placed Mermithiden. Zoologisches Jahrbuch Abteilung Sysin the genus Hexamermis as characterized tematik 32:521-612. 2. Kaiser, H. 1977. Untersuchungen zur Morby Rubtsov (1978). His classification re- phologie, Biometrie, Biologie und Systematik yon stricts the genus to forms that possess a Mermithiden. Ein Beitrag zum Problem tier Trenhorn-shaped, rather than an S-shaped, va- hung morphologisch schwer unterscheidbarer Arten.

Hexamermis cathetospiculae n. sp.: Poinar, Chang 363 ZoologischesJahrbuch, Abteilung Systemafik 104:2071. 3. Nickel, J. L. 1964. Biological control of rice stemborers: A feasibility study. Tech. Bull. No. 2. International Rice Research Institute, Los Banos, Philippines. 4. Pagden, H. T. 1930. A preliminary account of three rice stem borers. Scientific Series, Department

of Agriculture. Straits Settlements and Federated Malay States No. 1. 5. Rao, V. P. 1966. Survey for natural enemies of pests of paddy. Report U.S. PL-480 Project Commission of the Institute of Biological Control. 6. Steiner, G. 1925. Mermithids parasite in the tea bug (Helopeltis antonii Sign). Mededeelingen van het Proefstation voor thee 44:10-16.

Journal of Nematology 17(3):363-366. 1985. © T h e Society of Nematologists 1985.

Susceptibility of the Carrot Weevil (Coleoptera: Curculionidae) to Steinernema feltiae, S. bibionis, and Heterorhabditis heliothidis 1 G u Y BI~LAIR AND G u Y BOIVIN 2

Abstract: Larvae, pupae, and adults of the carrot weevil (Listronotus oregonensis) were infected and killed by the three entomophagous nematodes (Steinernema feltiae, S. bibionis, and Heterorhabditis heliothidis) u n d e r controlled conditions. Third-stage larvae were more susceptible than pupae or adults. S. feltiae and S. bibionis were the most aggressive nematode species, causing larval mortality after 2 4 - 4 8 hours in b o t h continuous and 2-hour contact with nematode suspension. T h e nematodes multiplied sufficiently in all insects at all stages of development; however, production of infectivestage larvae per host cadaver was variable. Key words: entomogenous nematodes, Listronotus oregonensis, control.

T h e carrot weevil, Listronotus oregonensis Le Conte (Coleoptera: Curculionidae), is an important pest of carrot, parsley, and celery in eastern Canada and northeastern United States (7,8,10). Chemical insecticides, applied as granules at seeding time or as foliar sprays, are the only method available to control this insect. If integrated pest management (IPM) programs are to be applied in these crops, alternative control methods are needed. Biological control could potentially replace some chemical treatments, but no information is available on pathogens of L. oregonensis. Many entomophagous nematode members of the family Steinernematidae and Heterorhabditidae have wide host ranges. Some are promising biological control agents in IPM programs (6). This laboratory study was undertaken to determine

Received for publication 13 November 1984. Contribution No J-980 from Research Station, St-Jeansur-Richelieu. 2 Nematologist and Entomologist, Agriculture Canada, Research Branch, Research Station, St-Jean-sur-Richelieu, Quebec, Canada J3B 6Z8. We thank Claude Granger, Yvon Fournier, and Danielle Thibodeau for their technical assistance.

the susceptibility of larvae, pupae, and adults o f L. oregonensis to infection by Heterorhabditis heliothidis (Khan, Brooks, and Hirschmann), Steinernema feltiae Filipjev, and S. bibionis Steiner under continuous and short exposure periods in the laboratory. MATERIALS AND METHODS

T h e three nematode species H. heliothidis, S. feltiae DD-136 strain, and S. bibionis T335 were obtained from Dr. J. W. Webster, Simon Fraser University, Vancouver, Canada, and reared on larvae of the greater wax moth, Galleria mellonella (L.), by the method of Dutky et al. (2). Carrot weevils were reared on carrots by the method of Martel et al. (4). Adults were originally collected in c a r r o t fields in southwestern Quebec; the weevil was in its sixth to eighth generation in laboratory culture. Third-instar larvae, pupae less than 48 hours old, and adults 2 - 3 months old were used in the tests. For infection experiments, 20 insects (larvae, pupae, or adults) were placed in each 10-cm-d sterile petri dish lined with two #2 Whatman filter papers. T h r e e milliliters of water containing approximately