Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: August 15, 2003
Publication Date: August 15, 2003
Citation: VANDENBERG, J.D., CASTRILLO, L.A., GRIGGS, M., ANNIS, S.L., GRODEN, E. COMPARATIVE VIRULENCE OF WILD TYPE AND RECOMBINANT VEGETATIVELY COMPATIBLE STRAINS OF BEAUVERIA BASSIANA AGAINST COLORADO POTATO BEETLE. PROCEEDINGS OF THE ANNUAL MEETING OF THE SOCIETY FOR INVERTEBRATE PATHOLOGY. 2003. v. 36. p. 48-49.
We developed a system for grouping strains of Beauveria bassiana according to the vegetative compatibility of nitrate non-utilizing (nit) mutants. We showed that members of one vegetatively compatible group were genetically quite similar. All of these isolates originated in eastern North America and all were associated with Colorado potato beetle. We obtained recombinants of two compatible pairs of isolates (ARSEF 252 x ARSEF 5813 and ARSEF 5813 x ARSEF 6986) by coinoculating beetles and screening fungal progeny from cadavers. We wished to determine whether this form of recombination could influence pathogenicity and virulence. In this study we report the results of a series of dose-response assays to compare parent nit mutants and their recombinant progeny. Our assays included 4 dosages for each isolate and 30 beetles per dosage. Beetles were reared individually and observed daily for one week. Each assay was done at least 3 times on different dates for each set of isolates. A standard strain (GHA) was included in each assay. Probit analysis was used to estimate slopes and LC50s. Average survival times were computed and compared. Recombination between vegetatively compatible strains occurred in vivo at very low frequency. Quantitative changes in pathogenicity or virulence have not yet been detected among recombinants. The movement of virulence-related genes during heterokaryon formation has been shown among plant-pathogenic fungi. Further studies are needed to determine if this phenomenon occurs among insect-pathogenic strains of B. bassiana.