Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 25, 2004
Publication Date: August 1, 2004
Citation: Castrillo, L.A., Griggs, M., Vandenberg, J.D. 2004. Virulence to colorado potato beetles and genetic stability of beauveria bassiana parasexual recombinants [abstract]. Society for Invertebrate Pathology Annual Meeting Proceedings. 37:84. Technical Abstract: We wished to determine the potential for recombination between strains of Beauveria bassiana and whether recombination could result in new strains with altered virulence or host range. We co-inoculated Colorado potato beetle larvae with vegetatively compatible strains ARSEF 5813 and ARSEF 6986 and recovered spore progeny for bioassay and molecular analysis. By using nitrate reductase mutants, recombinants were readily detected by their prototrophic growth compared to sparse growth produced by parent strains or any non-recombinant spore progeny on minimal medium. Sampling among the recombinant spore progenies revealed isolates with altered virulence. Bioassays using third instar CPB larvae showed isolates more virulent, less virulent, or of comparable virulence to their parent strains. To determine whether this phenotypic change is stable, we conducted a serial passage study of three representative strains using CPB larvae. Since repeated passage through a susceptible host has been shown to enhance virulence in some B. bassiana strains, the parent strains were also included in this study. Preliminary analysis of our data indicates that changes in virulence we observed among recombinants is stable and that repeated passage through CPB larvae did not alter virulence of neither parents nor recombinants. Additional assays are underway. We are also conducting molecular analysis of parent strains and recombinant spore progenies to determine if recombinant strains are genetically stable after serial passage in vivo.