Molecular Identification Of Entomopathogenic Nematodes In Gansu Province

Entomopathogenic nematodes(EPN) is a group of nematodes that parasitize on insects with diversified morphological characters and hostsPeeifieity. Beeause of their biological control value, it is important to study genetic variations and Phylogenetic relations of these entomopathogenic nematodes. However the classifieation and evolutionary relationships of them have always been hindered by the overwhelming number of species,global distribution, and the laek of morphological speeializations traditionally used in nematode classifieation. The eonfusion and debates have brought much trouble not only to the study of the Phyologenetic relationships among groupers, but also to the biological control. The molecular systematic research on Mermithidae is still very limited.The rDNA sequences of 29 geographic regions EPN in 8 different described species were tested using PCR amplified It was found that the fragments length of 26DNA region of all the nematode specimen was about 1100bp.The above results were supported by further examination of these nematodes using morphological approach.Totally, the rDNA ITS regions of 29 rice root nematodes in eight different geographic regions were amplified and Phylogenetie analysis was made together with the associated sequcences in Genbank. At the same time,all the cloned PCR produets were digested with Restrietion enzymes, Alul. It was found that the fragments length of ITS region of all the 29 nematode specimen was about 1100bp. Three speeies were confirmed according to the phylogenenc tree. ITS-RFLPS showed that different species yield different digestion pattems. Some ITS-RFLPS phenotypes variation was detected among the introspecies populations. EcoR I-AluI of entomopathogenic nematodes had no difference, and had no polymorphism of variation in the different geographic regions.The present study provides an efficient ap proach for rapid identification of large number of EPN isolates obtained from survey, which is very beneficiary to studies such as EPN survey, taxonomy and systematic.Some tests were done about the antidesiccation abilities of 8 entomopathogenic nematode species of Gansu province, and the results showed that those abilities were different. At the condition of 25℃, RH 50.5% for 5h, 7h, 9h, the Steinernem species had the higher survival rate while Heterorhabdit were almost had the zero rate. Also the antidesication abilities were different among Steinernem species, S. kraussei's was higher than the other species. The survival rate was best at 25℃,RH50.5% for 9h. Both of S. kraussei and S.bicornutum could kill Galleriamellonela totally after dael with water.