Molecular Identification And Population Differentiation Of Trichogramma Spp.

Trichogramma spp. is the most widely studied and used egg parasitoids for biological control of insect pests in the world. This tiny parasitoid has been used with success in the control of pests of maize, rice, cottons, vegetables and forests. Correct species identification is the first step for a successful biological control program. Domestic and overseas entomologist has showed that different molecular marker methods for molecular identification of Trichogramma species. However, each of molecular marker methods previously has own deficiency, and molecular marker genes used in Trichogramma species identification almost is ribosomal DNA(rDNA), study about mitochomadrial DNA in Trichogramma spp. is infrequent. In this paper mitochondrial cytochrome oxidase I, mitochondrial cytochrome oxidase II and mitochondrial cytochrome b genes of different Trichogramma species and different geographical populations of the same Trichogramma species were analysed for feasibility for molecular identification of Trichogramma at species and infraspecific level. Exact Trichogramma species molecular identifications were realized based mtDNA.There are biological and ecological differences in different geographical populations and biotype of Trichogramma dendrolimi, moreover the differences might effect biological control efficiency. Meanwhile, the mass release of artificial breeding T. dendrolimi can alter the genetic structure of local wild populations.So, the geographical distribution and population differentiation of T.dendrolimi should be knowed before T.dendrolimi release. However, conventional biological method do not resolve the problem. Molecular markers create new theory and method for subspecies study of Trichogramma dendrolimi. In this paper, population differentiation and genetic structure of different geographical T. dendrolimi were studied using microsatellite molecular marker (SSR). At the same time, the correlations between population genetic structure and geographical environment, weather, as well as Wolbachia endosymbiont that might effect the genetic diversity of T.dendrolimi was also studied.The mtDNA COI, mtDNA CO II and mtDNA Cytb genes of different Trichogramma species and different geographical populations of the same Trichogramma species were sequenced, and the genetic distance and phylogenetic relationships of Trichogramma were respectively established based mtDNA gene sequences. It can be concluded that COI, CO II and Cytb are suitable for molecular identification at species level, and not suitable for molecular identification at infraspecific category. At the same time the Cytb was regarded as the most suitable gene for Trichogramma species identification.The Trichogramma species specific primers of T.dendrolimi, T.ostriniae, T.chilonis,...