Prevalence rates of Wolbachia endosymbiotic bacterium in natural populations of Ostrinia Nubilalis and Ostrinia Scapulalis (Lepidoptera: Pyraloidea: Crambidae) in South-Western Russia

Background. Endosymbiotic bacteria of the genus Wolbachia are widespread in arthropods and often cause reproductive abnormalities in lepidopteran insects, including corn borers of the genus Ostrinia. Wolbachia-Ostrinia is a promising model for studies of parasite-host interactions yet parasite prevalence in natural insect host populations remains unknown. Materials and Methods. Molecular genetic screening and statistical analysis is applied to evaluate prevalence rates of Wolbachia in sympatric populations of two corn borer species. Individual genomic DNA samples were extracted from last instar larvae collected in nature from different forage plants. For each sample of DNA showing positive signal with insect-specific primers the detection is performed using three diagnostic loci of Wolbachia: 16SrRNA, gatB and fbpA. Results. Wolbachia-positive signal is obtained for 13.5% larvae of Ostrinia nubilalis (N = 141) and 31.9% larvae of Ostrinia scapulalis (N = 138). In different localities the Wolbachia prevalence ranged from 2.9% (N = 34) to 65.8% (N = 38). Significantly higher rates of Wolbachia prevalence in insects from mugwort and hemp (O. scapulalis) as compared to those from corn (O. nubilalis) are revealed in three out of four localities. Conclusions. Endosymbiotic bacteria of the genus Wolbachia are revealed in natural populations of corn borers for the first time for Eastern Europe. The prevalence rates can be high and this should be taken into consideration when reproductive isolation is examined in population of these hosts as well as establishment of laboratory cultures is performed