A representation of Drilonematoidea (Rhabditida) biodiversity in museum collections

Elena S. IVANOVA, Sergei E. SPIRIDONOV*

Institute of Parasitology of RAS, Leninskii pr., 33, Moscow, 117071, Russia, *spiridon@rjnem.msk.ru

Four museum collections of earthworms from Moscow State University Zoological Museum, Smithsonian Natural History Museum (Washington, USA), Muséum Histoire d’ Naturelle (Genéve, Switzerland) and Musée Royal de l’Afrique Centrale (Tervuren, Belgique) were studied for presence of nematodes (Drilonematoidea) parasitizing in body cavity of these invertebrates. Formalin-preserved earthworms were dissected and parasites were recovered. Each earthworm collection except Tervuren one represents the local annelid fauna as well as the animals from around the world. The latter part of collections reflects mainly the scientific interests of researchers contributed. If the bulk of collection in Smithsonian consists from megascolecids from South East Asia, there are South American glossoscolecids and acanthodrilids in Geneva and Indochina megascolecids in Moscow and African octochaetids and eudrilids in Tervuren. Only 3-4% of earthworms in collections was found infected by parasitic Drolonematoidea, whereas infectivity varies in different annelid taxa. About 23% of megascolecid and tropical acanthodrilid earthworms and 2.5% of glossocolecids and 3% of octochaetids and eudrilids and less than 1% of lumbricids were found infected. If megascolecids and acanthodrilids serve as hosts for several dozens genera of Drilonematidae, Ungellidae, Homungellidae and Scolecophilidae families, there are members of only two genera of Drilonematidae parasitic in lumbricids, representatives of few ungellid genera in glossoscolecids and some ungellid and drilonematid genera inhabiting in octochaetids and eudrilids. From few to couple of dozens nematode specimens can be recovered usually from body cavity of earthworms from museum collections though maximum infectivity found in natural habitat was nearly four hundreds nematodes per earthworm.

The "intermedium-affine" group of Steinernema (Rhabditida, Steinernematidae): morphological and molecular characters

Elena S. IVANOVA, Sergei E. SPIRIDONOV*

Institute of Parasitology of RAS, Leninskii pr., 33, Moscow, 117071, Russia, *spiridon@rjnem.msk.ru

Steinernematids of "intermedium-affine" group are a separate clade in the genus phylogeny, consisting of two described species and numbers of poorly distinguishable isolates from Holarctic. Morphology of adults and infective juveniles was studied and ITS rDNA sequences were obtained for 4 European isolates of S. affine, 2 isolates of S. intermedium from USA, and 8 unidentified Eurasian isolates. According to the maximum parsimony analysis all Eurasian isolates clustered together, with S. affine forming strongly supported group with Estonian isolate EE3 and Swiss CH221. Type USA isolate of S. intermedium (Poinar, 1985) differs from European "intermedium-like" cultures by shorter male stoma (2.7 μm vs 8.4 μm in cultures close to UK E1 vs 4.5 μm in Caucasus isolate vs 5.5 μm in EE3). All Eurasian isolates were characterized by the presence of mucron on male tail (1-2 μm long in E1 UK and close cultures, 1-5 μm in EE3 and 4-12 μ in Caucasus isolate). The latter one from Caucasus ridge differs from all other studied isolates by having larger and stronger spicules with wider spicule tips and longer tail mucron (4-12 μm). This isolate demonstrates the highest number of nucleotide autapomorphies and total nucleotide differences. Nematodes of the isolates similar to UK E1 presented separate clade in the trees with 100% bootstrap support, with minor total nucleotide differences between separate isolates.

Contortylenchus genitalicola (Tylenchida: Allantonematidae): the sphaerularioid nematode with a fungal feeding phase and the potential biological control agent of the Japanese pine sawyer

Hajime KOSAKA

Department of Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan, hkosaka@ffpri.affrc.go.jp

Contortylenchus genitalicola Kosaka & Ogura, 1993 is one of the insect parasitic nematodes of the order Tylenchida (sphaerularioid nematodes). This nematode can develop not only through an insect parasitic phase but also through a fungal feeding phase. The insect host of C. genitalicola is the Japanese pine sawyer, Monochamus alternatus Hope, a serious forest pest and the vector of the pine wood nematode, Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, 1970, the cause of pine wilt disease, a serious disease worldwide. The fungal host of C. genitalicola is an unidentified fungus that was isolated from the single juvenile nematode recovered from the adult host insect. First in this presentation, the basic biology of C. genitalicola, the morphology and life cycle, is reported. Then, the potentials of C. genitalicola as the biological control agent, such as the effects on the host insect, geographical distribution and mass production through the fungal feeding phase, will be presented. The taxonomic status of C. genitalicola would be delicate because different researchers allocate the fungal feeding sphaerularioids to different taxa. There are also some obstacles to develop the biological control using C. genitalicola. Further studies to break these barriers are discussed.

Nematode fauna from hind gut of diplopods from Guadeloupe, French West India

Svetlana V. MALYSHEVA¹, Sergei E. SPIRIDONOV²

¹Department of Invertebrate Zoology, Faculty of Biology, Moscow State University, Moscow, 119899

²Institute of Parasitology of RAS, Leninskii pr., 33, Moscow, 117071, Russia, spiridon@rjnem.msk.ru

Specimens belonging to four species of diplopods were collected in July 1996 in Guadeloupe, French West India. Leptogoniulus naresi (Pocock, 1893) and Trigoniulus lumbricinus (Gerstacker, 1873) were collected from compost heaps behind households in Gosier, Grande Terre. Anadenobolus politus (Porat, 1889) and Pseudospirobollellus avernus (Butler, 1876) were collected under leaf litter in the tropical forest near "Maison de la forêt" in Basse Terre. Twelve dissected L. naresi contained 3 species of nematodes: Heth mauriesi, Rhigonema caribae and Ruizia karukerae. H. mauriesi, Thelastoma sp. and two early juveniles of Rhigonema sp. were found in fifteen specimens of T. lumbricinus collected together with L. naresi. Thelastomatid nematodes of unknown genus were found in 9 dissected specimens of P. avernus, being accompanied with separate Galinanema females, few specimens of Heth and Rhigonematidae juveniles. Six specimens of large A. politus contained the richest fauna of nematodes: Heth mauriesi, Carnoya kermarreci, Ichthyocephalus anadenoboli, Rhigonema sp., Galinanema sp., Thelastoma sp. and unknown thelastomatid. Infection intensity varied significantly in A. politus: when two specimens contained several dozens of Ichthyocephalus anadenoboli males, females and juveniles, about a dozen of adult Heth maurieci and Carnoya kermarreci specimens and numerous juveniles of rhigonematids and thelastomatids, whereas four remaining A. politus contained only few juveniles. Observed differences in nematode fauna in both pairs of sympathric diplopods indicate that some host specificity exists in thelastomatid and rhigonematid nematodes. It seems that some exotic nematodes (Carnoya, Galinanema) can be found only in primary tropical habitats.

Entomoparasitic tylenchids Spilotylenchus (Sphaerularioidea, Tylenchida) cause malformations in male reproductive system of flea Coptopsylla lamellifer (Siphonaptera)

Olga V. SLOBODYANYUK

Institute of Parasitology of RAS, Leninskii pr., 33, Moscow, 117071, Russia, spiridon@rjnem.msk.ru

The nematode Spilotylenchus pawlowskyi (Spilotylenchidae, Sphaerularioidea) is parasite of a body cavity of flea Coptopsylla lamellifer which is ectoparasite of gerbils Meriones meridianus and M. tamariscinus. It was shown that the nematode infection caused the malformations of male flea reproductive system and modified segments of the insect hosts. Majority of infected flea males were found sterilized by reduction of phallosome and absense of testes. Also the lack of aedeagus and penis apophyses were often observed as well as the various malformations of modified segments, which represent normally a complex organ for fixing flea female during copulation. Measuring decrease, shape deformation and non-typical telomere armament, basimere narrowing, atypical set of basimere distal setae, manubrium and apodeme malformations were discovered in infected males. Shape deformation, measuring descrease, setae reduction of IX sternite horizontal arm, reduction and non-characteristic shape of IX sternite vertical arm, number and length of antesensill setae decrease, particularly the lowest one, the erratic shape and armament of VIII sternite and occasionally loss of bilateral symmetry were also revealed in infected flea males under teratogenic pressure. Amount of S. pawlowskyi juveniles in host abdomen was found not to affect on nematode teratogeneity though their number differ from few to several thousands juveniles. However some correlation between number of parasitic females penetrated into host haemocoel and number and degree of some malformations were revealed in flea males invaded by four and more parasitic females. Parasitogenous malformations of male reproductive systems caused unability of males to copulate with females.

The influence of Spilotylenchus (Sphaerularioidea, Tylenchida) nematode infection on flea Coptopsylla lamellifer (Siphonaptera, Coptopsyllidae) female reproductive system

Olga V. SLOBODYANYUK

Institute of Parasitology of RAS, Leninskii pr., 33, Moscow, 117071, Russia, spiridon@rjnem.msk.ru

The teratogenic effect of Spilotylenchus pawlowskyi (Sphaerularioidea, Spilotylenchidae) on female sexual organs and modified segments of flea Coptopsylla lamellifer was studied. Infected fleas were collected in the Astrakhan region, in Aral lake area and Muyunkum desert. Most of examined flea females were found sexually abnormal and lacking ovaries and the single female C. lamellifer from Muyunkum desert was found having the underdeveloped ovaries with no signs of undergoing oogenesis. A set of malformations such as deformation of spermathecs, vagina shortening, reduction and different degree of sclerotization of copulative duct (ductus bursae copulatricis), shape deformation and non-typical armament of anal segments, lesser length and number of antesensill seta were found in reproductive system of infected flea females. Also the bilateral symmetry disturbances of the modified segments were discovered in some flea female specimens. In fact, the teratogenic effect of S pawlowskyi on flea female C. lamellifer sexual organs is as large as causing inability of infected flea females for reproduction. Some taxonomically significant flea features such as number and shape of spermathecs and shape of copulative duct could be so much changed by teratogenic effect that it made difficult the identification of infected fleas.

Teratogenic effect of entomoparasitic tylenchids (Sphaerularioidea, Spilotylenchidae) in three populations of plague-vector fleas Coptopsylla lamellifer (Siphonaptera, Coptopsyllidae)

Olga V. SLOBODYANYUK¹, Nadezda L. GERSHKOVICH²

¹Institute of Parasitology of RAS, Leninskii pr., 33, Moscow, 117071, Russia, spiridon@rjnem.msk.ru

²Zoological Museum of Moscow State University, Bolshaya Nikitskaya str., 6, Moscow,103009, Russia

The nematode Spilotylenchus pawlowskyi (Sphaerularioidea, Tylenchida) is parasite in a body cavity of plague-vector flea Coptopsylla lamellifer which are ectoparasites of gerbils Meriones meridianus and M. tamariscinus. Comparative study of pathomorphology of fleas infected by entomoparasitic tylenchids from three plague natural habitats has been carried out. Infected fleas C. lamellifer dubinini were obtained in Astrakhan region, in Aral lake area and Muyunkum desert ("astrakhan", "aral" and "muyuncum" populations respectively). 36 morphological characters of flea male reproductive system and modified segments and 14 ones of females were studied and it was found that nematodes infection caused strong malformations in all populations studied. However, teratogenic effect in three populations differs from the most impact in "astrakhan" population to the least one in "muyuncum" population. Analysis of morphometry of three insect populations revealed reliable differences between populations based on characters of flea male morphology such as size and shape of phallosome rudiments, as well as manubrium and apodeme of IX tergite and vertical arm of IX sternite. The presence of testes, aedeagus rudiments, and penis apophyses were discovered only in some infected male specimens in "muyuncum" population whereas no males with these organs were found in two other populations. The lack of basimere and intersexual characters were discovered only in some infected male specimens in "aral" population. Female pathomorphology is less of males one in the studied populations. Size and shape of sclerotized copulative duct (ductus bursae copulatricis) and loss of bilateral symmetry were considered as the most affected features.

Comparative study of three coastal steinernematids, Steinernema feltiae, Steinernema sp. RFLP type MY2 and Steinernema sp. RFLP type MY8

Mutsuhiro YOSHIDA

National Institute for Agro-Environmental Sciences, Kannondai Tsukuba, Ibaraki, Japan, mutsuysd@niaes.affrc.go.jp

As a result of a series of survey for the entomopathogenic nematodes in Japan and Russian Far East, Steinernema feltiae and Steinernema. spp. RFLP types MY2 and MY8 were considered to be coastal steinernematids in the survey regions and many isolates of them were detected from grassland in sandy beach. S. feltiae was isolated from southern part of Sakhalin and Hokkaido, Steinernema sp. MY2 from Hokkaido to central part of Honshu and Steinernema sp. MY8 from central part of Honshu to Amami-Oshima Is., south of Kyushu. S. feltiae and S. sp. MY2 were isolated sympatrically in Hokkaido, while Steinernema sp. MY2 and Steinernema sp. MY8 were isolated allopatrically from the same coast in the boundary area of their distribution. S. feltiae and Steinernema sp. MY2 showed many morphological similarities. From the lateral field pattern of infective juveniles, Steinernema spp. MY2 and MY8 were sorted into a group, which belonged to the glaseri group, but they were clearly discriminated morphologically from each other. As for pathogenicity for some species of lepidopteran larvae, Steinernema sp. MY8 showed much lower mortality as compared with S. feltiae and Steinernema sp. MY2. S. feltiae and Honshu isolates of Steinernema sp. MY2 showed high pathogenicity at 10°C, however Hokkaido isolates of Steinernema sp. MY2 showed low pathogenicity at 10°C. In this report, the biological relationship among two morphological related species and the third species, which showed the same habitat preference as the former two species, will be discussed with some data on their distribution and pathogenicity.

© Russian Society of Nematologists, Institute of Marine Biology FEB RAS, 2002