Taxonomic study of entomopathogenic nematodes (Nematoda : Steinernematidae, Heterorhabditidae) from Benin

A study on the biodiversity of entomopathogenic nematodes was conducted during 2010 and 2011 in South Benin. Soil samples from eight sites production of annual and perennial crops were analysed. We obtained 13.21 % of positive soil samples out of 280. We here report on the identification of six of these isolates. Molecular, morphometrical and morphological observations classified the isolates within the genus  Heterorhabditis ; one isolate was conspecific with H. indica and two other isolates with H. sonorensis . More information is needed for effective identification of the remaining three isolates. Phylogenic analysis based on sequences of ITS regions of rDNA grouped our isolates with H. sonorensis and H. taysearae with bootstrap support values of 94 and 99 % in Maximum Parsimony and Neighbour Joining trees, respectively. Morphological characters of the infective juveniles and males did not correspond to those of H. taysearae , but were close to H. sonorensis. In contrast, the female of the H. sonorensis populations did show some minor differences with the originally described one. No progeny was obtained from the crossbreeding of Beninese isolates and H. taysearae. Crossing with an isolate of H. sonorensis would have been more conclusive, but no isolates were available even for specimen’s morphological comparison. Keywords : Survey, identification, Molecular, cross-hybridization, Heterorhabditis. Etude taxonomique desnematodes entomopathogenes (Nematoda : Steinernematidae, Heterorhabditidae) du Benin Une etude diagnostique realisee sur les nematodes entomopathogenes (NEP) en 2010 et 2011 dans le Sud- Benin sur huit sites de production de cultures annuelles et perennes a conduit a 13,21 % d’echantillons de sols positifs sur 280. Le present travail a porte sur l’identification de six des isolats de NEP extraits. Les etudes moleculaires, morphologiques, morphometriques et d’hybridation effectuees utilisant les stades developpementaux des nematodes ont revele un isolat d ’H. indica , deux d’ H. sonorensis . Pour les autres isolats, des informations complementaires sont necessaires pour une identification complete. Le sequencage et l’analyse phylogenetique de la region interspecifique de l’ADN ribosomal ont groupe nos isolats avec H. sonorensis et H. Taysearae dans les arbres de parcimonie maximale et de Neighbour Joining avec les supports respectifs 94 et 99 %. Les caracteres morphologiques des juveniles infectieux et des mâles ne correspondent pas a ceux de la premiere description d’H. taysearae, mais sont proches d’ H. sonorensis.  Cependant, certaines femelles avec bouchon copulatoire ne correspondent pas a H. sonorensis . Nos isolats n’ont pas ete feconds avec H. taysearae . Un croisement avec H. sonorensis population type serait plus concluant, mais il n’y avait aucun isolat disponible dans la base de genes. Mots-cles : Etude, identification, moleculaire, hybridation-croisee, Heterorhabditis.

[1]  W. Crow,et al.  First record of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) from Nigerian soil and their morphometrical and ribosomal DNA sequence analysis , 2012 .

[2]  M. Moens,et al.  Distribution of entomopathogenic nematodes in Southern Cameroon. , 2012, Journal of invertebrate pathology.

[3]  E. Brusselman.  Optimizing the spray application of entomopathogenic nematodes in vegetables: from spray tank to nematode deposition , 2011 .

[4]  W. Bert,et al.  Mononchoides composticola n. sp. (Nematoda:Diplogastridae) associated with composting processes: morphological, molecular and autecological characterisation , 2011 .

[5]  K. Nguyen,et al.  Chapter 5. Heterorhabditidae: Species Descriptions , 2010 .

[6]  K. Nguyen.  Chapter 3. Methodology, Morphology And Identification , 2010 .

[7]  S. Stock,et al.  Heterorhabditis sonorensis n. sp. (Nematoda: Heterorhabditidae), a natural pathogen of the seasonal cicada Diceroprocta ornea (Walker) (Homoptera: Cicadidae) in the Sonoran desert. , 2009, Journal of invertebrate pathology.

[8]  K. Nguyen,et al.  Entomopathogenic Nematodes: Systematics, Phylogeny and Bacterial Symbionts , 2008 .

[9]  K. Nguyen,et al.  Heterorhabditis safricana n. sp. (Rhabditida: Heterorhabditidae), a new entomopathogenic nematode from South Africa , 2008 .

[10]  M. Goettel,et al.  Biological Control: A Global Perspective , 2007 .

[11]  R. Ehlers,et al.  Entomopathogenic nematodes: from science to commercial use. , 2007 .

[12]  Johannes Helder,et al.  Phylum-wide analysis of SSU rDNA reveals deep phylogenetic relationships among nematodes and accelerated evolution toward crown Clades. , 2006, Molecular biology and evolution.

[13]  R. Ehlers,et al.  Status of entomopathogenic nematodes and their symbiotic bacteria from selected countries or regions of the world , 2006 .

[14]  R. Ehlers,et al.  Dangerous liaisons: The symbiosis of entomopathogenic nematodes and bacteria , 2006 .

[15]  L. Uribe-Lorío,et al.  First record of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) in Costa Rica. , 2005, Journal of invertebrate pathology.

[16]  Urnell,et al.  Molecular characterisation of Heterorhabditis indica isolates from India , Kenya , Indonesia and Cuba , 2005 .

[17]  S. Subbotin,et al.  Heterorhabditis baujardi sp. n. (Rhabditida: Heterorhabditidae) from Vietnam and morphometric data for H. indica populations , 2003 .

[18]  A. Burnell,et al.  Molecular characterisation of Heterorhabditis indica isolates from India, Kenya, Indonesia and Cuba , 2000 .

[19]  S. Stock,et al.  A multivariate analysis of morphometric characters of Heterorhabditis species (Nemata: Heterorhabditidae) and the role of morphometrics in the taxonomy of species of the genus. , 1996, The Journal of parasitology.

[20]  R. Ehlers,et al.  Culture conditions define automictic or amphimictic reproduction in entomopathogenic rhabditid nematodes of the genus Heterorhabditis , 1994 .

[21]  R. Akhurst,et al.  DNA Relatedness between Xenorhabdus spp. (Enterobacteriaceae), Symbiotic Bacteria of Entomopathogenic Nematodes, and a Proposal To Transfer Xenorhabdus luminescens to a New Genus, Photorhabdus gen. nov. , 1993 .

[22]  G. Poinar,et al.  Heterorhabditis indicus n. sp. (Rhabditida: Nematoda) from India: separation of Heterorhabditis spp. by infective juveniles. , 1992 .

[23]  W. M. Wouts.  Mass Production of the Entomogenous Nematode Heterorhabditis heliothidis (Nematoda: Heterorhabditidae) on Artificial Media. , 1981, Journal of nematology.

[24]  G. Poinar,et al.  Xenorhabdus gen. nov., a Genus of Entomopathogenic, Nematophilic Bacteria of the Family Enterobacteriaceae , 1979 .

[25]  R. Bedding,et al.  A simple technique for the detection o f insect paristic rhabditid nematodes in soil , 1975 .

[26]  J. Seinhorst.  A Rapid Method for the Transfer of Nematodes From Fixative To Anhydrous Glycerin , 1959 .

[27]  V. Miller,et al.  TAF, an improved fixative in nematode technique. , 1955 .

[28]  N. Cobb.  Estimating the nema population of soil, with special reference to the sugar-beet and root-gall nemas, Heterodera schachtii Schmidt and Heterodera radicicola (Greef) Müller , 2022 .