Sergei E. Spiridonov

Biosystematics of entomopathogenic nematodes : current status, protocols and definitions

COST Action 819: Entomopathogenic nematodes , supercedes Action 812: Cold active lines of insect parasitic nematodes in Agriculture and Biotechnology . It functions in the field of Agriculture and Biotechnology and began in July 1994 and will end in May, 1999. The main objective is to combine interrelated European expertise to increase the use of entomopathogenic nematodes (EPNs) in integrated pest management and to reduce the need for chemical control. Coordination of the Action is the responsibility of a management committee in accordance with a Memorandum of Understanding, which has been signed by representatives of 17 countries: Austria, Belgium, Czech Republic, Finland, France, Germany, Hungary, Ireland, Italy, The Netherlands, Norway, Poland, Portugal, Spain, Sweden, Switzerland and the UK. A research institute in Israel is also participating. Over 40 research institutions and 10 commercial companies participate in Action 819. The EU funding meets the costs related to coordination including the scientific secretariat, workshops, management committee and working group meetings, publications, short term scientific missions and evaluations.

Molecular phylogeny of slug-parasitic nematodes inferred from 18S rRNA gene sequences

Terrestrial molluscs are diverse and are infected by many nematodes. We propose a phylogeny of slug-parasitic nematodes using 18S rRNA gene sequences from nematodes isolated from slugs collected from six countries. Eight species, representing six families of nematodes were identified and trees inferred placed them within four (I, III, IV and V) out of the five clades of Nematoda, indicating multiple origins of slug parasitism. Five species representing three families formed a monophyletic group in clade V. Although these species are closely related, their morphology has changed greatly, suggesting adaptive radiation to fill different niches within the host.

Four new species of Heth Cobb, 1898 (Rhigonematida: Hethidae) from Vietnamese diplopods.

Four new species of Heth are described from diplopods collected in different parts of Viet Nam: Heth vietnamensis sp. n. and H. tonkinensis sp. n. in Ba Vi National Park, Ha Tay Province; H. taybaci sp. n. in Lai Chau Province and H. taynguyeni sp. n. in Chu Yang Sin National Park, Dak Lak Province. The new species are morphologically related to those described from Papua New Guinea, but are differentiated by the form of the female cuticular armature. Heth vietnamensis sp. n. is characterised by the posterior end of the lappets overhanging the anterior pair of the lateral spines, the similar size of spines in both pairs and the presence of two pairs of small papillae on the anterior lip of the cloacal aperture. Heth tonkinensis sp. n. can be differentiated from the other species by having the longest lappets, lateral spines with fused bases and the unequal-sized spicule heads. Heth taybaci sp. n. has the shortest lappets of the described Vietnamese species, has gaps between the lateral spines that are wider than the spine base and the presence of a bursa-like cuticular fold at cloacal aperture level. Heth taynguyeni sp. n. males also have a bursa-like cuticular fold but, unlike H. taybaci sp. n., this species is characterised by the bifurcate distal tips of the spicule and the undulating inner margin of the lappets.

Riders on the sperm: sperm dimorphism and spermatozeugmata in nematodes from the genus Steinernema (Rhabditida: Steinernematidae)

A comparative ultrastructural study of the male gametes in entomopathogenic nematodes of the genus Steinernema (Rhabditida: Steinernematidae) is based on two species producing monomorphic (S. feltiae) and dimorphic (S. tami) spermatozoa. The spermatozoa of both species are basically the same as in many other Rhabditida. Immature spermatozoa from the testis are unpolarised cells containing a nucleus without a nuclear envelope, mitochondria and membranous organelles (MO), a unique component of the nematode spermatozoa. Mature spermatozoa have a nucleus, mitochondria and emptied MO, each attached to a sperm plasmalemma and opening to the exterior via a pore. Monomorphic mature spermatozoa of S. feltiae are 5 μm in diam., bear pseudopods, and form chains of several cells joined by gap junctions. The dimorphic immature spermatozoa of S. tami form spermatozeugmata where the single giant megaspermatozoon (30-35 μm diam.) bears numerous tiny, 3 μm microspermatozoa, intimately attached to the megaspermatozoon surface by gap junctions. Mature megaspermatozoa from the uterus are motile cells 35-50 μm diam.; they have prominent pseudopods and convey immotile, 2 μm microspermatozoa towards the oviduct. Unlike many other invertebrates, sperm dimorphism in S. tami does not change the basic set and structure of organelles, only their number. The genus Steinernema has two strategies for sperm agglomeration: i) chains of monomorphic spermatozoa of normal size, as in S. feltiae; and ii) spermatozeugmata based on a dramatic size difference between spermatozoa formed in the testis, as exemplified by S. tami. According to the types of sperm agglomeration, the genus Steinernema is divided into two main clades.

Steinernema lamjungense n. sp. (Rhabditida: Steinernematidae), a new species of entomopathogenic nematode from Lamjung district, Nepal

A new species of entomopathogenic nematode, Steinernema lamjungense n. sp., was recovered from soil samples collected from Tarku, Lamjung district of Nepal, during a survey in 2007. The analysis of ITS-rDNA sequence placed S. lamjungense n. sp. in the arenarium-glaseri-karii-longicaudum group. The nematode can be separated from other described species of the group by morphological and morphometric characteristics of different stages and by characterisations and phylogeny of DNA sequences of the D2D3 domain of the LSU or ITS regions of rDNA. For infective juveniles, the new species can be recognised by medium-long body length of 832 (690-950) μ m, pharynx length of 127 (110-142) μ m, H% = 61 (55-69) and E% = 79 (69-97). The lateral field pattern is 2, 6, 7, 8, 3, 2. The males have well curved, yellowish-brown spicules with a prominent velum. The spicule terminus is blunt with a longitudinal ventral notch. Spicule length is 87 (81-94) μ m and gubernaculum length is 57 (50-66) μ m in the first generation males. A tail mucron is absent in first but present in second generation males. First generation males have a lateral field with a single ridge. A post-anal swelling is not developed in first generation females but is well developed in second generation females. Three other isolates of the same species were recovered from the neighbourhood of the type locality and yet another isolate was collected from Swarketari, Syangja district.

Aulacnema monodelphis n. g., n. sp. and Angiostoma coloaense n. sp. (Nematoda: Rhabditida: Angiostomatidae) from terrestrial molluscs of Vietnam

Two species of nematodes, Angiostoma coloaense n. sp. and Aulacnema monodelphis n. g., n. sp. (Angiostomatidae: Rhabditida) are described from terrestrial molluscs of Vietnam. Both species are characterised by a long bowl-shaped buccal cavity and typically angiostomatid male bursal alae, spicules and gubernaculum. The new genus, Aulacnema n. g., is erected for the first reported monodelphic angiostomatid. Angiostoma coloaense n. sp. can be distinguished from other species of Angiostoma Dujardin, 1845 by having a buccal cavity length greater than its width and the absence of tail spikes on both males and females.

Steinernema kraussei (Rhabditida, Steinernematidae) from Iceland

Abstract A survey of soils from Iceland for the presence of cold-active entomopathogenic nematodes yielded a single isolate of Steinernema kraussei. This isolate was compared morphologically with the topotype from Westphalia, Germany, and was found to be similar except that the strain from Iceland had shorter mucrons and a longer gubernaculum in second-generation males. A fragment of the ribosomal DNA (internal transcribed spacer 1 [ITS1] + 5.8S + ITS2) was amplified and sequenced along with 7 other isolates of S. kraussei, 2 isolates from Switzerland, 1 isolate from Scotland, and 4 isolates from Russia. Phylogenetic trees prepared using maximum parsimony methods placed the strain from Iceland in a cluster with 2 Russian strains. The virulence of S. kraussei from Iceland against larvae of Tenebrio molitor was compared with that of a commercially available strain of Steinernema feltiae at 12°C and 4°C. At 12°C the strain from Iceland was less virulent than S. feltiae, and at 4°C the strain from Iceland demonstrated no detectable virulence, whereas S. feltiae evinced limited virulence.

Born to be Wild – Don’t Forget the Invertebrates

Parasitology research mostly aims to control parasites of humans and domesticated animals. Recently, many scientists have realized much can be learned by studying wildlife parasites. To this end, Trends in Parasitology published two special issues comprising some of the most interesting, topical science relating to wildlife parasitology [1]. The emphasis of the published articles was almost exclusively on parasites that use vertebrate animal hosts. Here, we argue that progress in parasitology could be accelerated if more parasitologists studied parasites that use invertebrates as definitive hosts.

A new genus of Carnoyidae (Nematoda: Rhigonematida) with descriptions of Cattiena trachelomegali gen. n., sp. n. and C. trigoniuli gen. n., sp. n., parasites of Spirobolida (Diplopoda) from Vietnam

Cattiena gen. n., a new genus from the Carnoyidae, is described from the posterior gut of two genera of spirobolid diplopods from Vietnam. The new genus is characterised by: presence of eight somatic spine rows in the cervical region of both male and female, the four sublateral spine rows being better developed; presence of six cuticularised plates around the female oral opening; extremely posterior vulva; two anteriorly directed ovaries; isomorphic and isometric spicules; boat-shaped gubernaculum of similar form to the spicules; gubernaculum with a dorsal hole; well developed, smooth cephalic cap in the male and 15 copulatory papillae with three pairs located lateral, sublateral or subdorsal. The new genus has morphological affinities with Raonema Kloss, 1965, a poorly known genus from India, but is easily differentiated by the extremely posterior vulva and the presence of spine rows in the male. Two new species are described in the genus: the type, C. trachelomegali gen. n., sp. n. from Trachelomegalus sp. and C. trigoniuli gen. n., sp. n. from Trigoniulus sp. The two species differ primarily in the position of the vulva (consistently more anterior in the latter species), degree of development of the vulval flap, body length, tail length and in the relative development of the somatic spine rows.

New nematodes of the families Drilonematidae, Ungellidae, and Mesidionematidae from New Zealand megascolecid earthworms.

Abstract Iponema australe sp. n. and Siconema neozealandicum sp. n. are described from New Zealand endemic earthworms. Both new species are aberrant species in their genera. I. australe (Drilonematidae) is characterised by the ornamented eggshells with polar surface differentiation, nerve ring around the intestine, and four cephalic sensillae. Characteristic features of S. neozealandicum (Ungellidae) are cephalic hooks with diverging tips and thick bases, the tuberculate surface of the eggshell, and the presence of a lumen in the ovary. Females of an undescribed genus show features in common with Drilonematidae, including unusually large suckers with fibrous underlying tissue; however, the absence of males in our material does not permit formal identification. Three new species of Nemanoke gen. n. are described from Octochaetus huttoni (Beddard, 1892). N. pharyngata sp. n. can be distinguished from the two other new species by the long oesophagus: 670–770 urn compared with 310–361 μm in Nemanoke stomicula...