Submitted to: Society for Invertebrate Pathology Annual Meeting
Publication Type: Abstract only
Publication Acceptance Date: 7/31/2005
Publication Date: 8/11/2005
Citation: Castrillo, L.A., Griggs, M., Groden, E., Annis, S.L., Mishra, P.K., Vandenberg, J.D. 2005. Changes in virulence to colorado potato beetles of beauveria bassiana gha isolates recovered from sprayed fields one to four years post application [abstract]. Society for Invertebrate Pathology Annual Meeting. 38:29. Interpretive Summary:
Technical Abstract: Our study on the impact of inundative releases of Beauveria bassiana GHA mycoinsecticides on indigenous conspecific populations revealed persistence of the GHA strain in the field four years at most since the last application. Molecular analysis of recovered GHA "clones" using AFLP markers also revealed detectable genetic changes distinguishing the field collected isolates from the sprayed technical products. Because genetic stability is important in assessing environmental risks of an introduced fungal entomopathogen, any genetic change and, consequently, correlated phenotypic changes, especially virulence and host range, need to be examined for non-target effects. In this study we examined virulence changes by conducting bioassays against the Colorado potato beetle of three GHA field-recovered "clones" versus a GHA technical product. Results showed that strains A18 and FA1 were of comparable virulence to the technical product, while strain G30 had significantly lower virulence. Among the GHA-like strains, A18 and FA1 were collected a year after the last GHA application and were genetically very similar to the technical product. In contrast, G30, collected four years after the last spray, has mixed ancestry, suggesting that the lower virulence in this strain may be due to recombination between GHA and an indigenous isolate.