Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 2002
Publication Date: October 1, 2002
Citation: SHAPIRO ILAN, D.I., REILLY, C.C., HOTCHKISS, M.W., WOOD, B.W. THE POTENTIAL FOR ENHANCED FUNGICIDE RESISTANCE IN BEAUVERIA BASSIANA THROUGH STRAIN DISCOVERY AND ARTIFICIAL SELECTION. JOURNAL OF INVERTEBRATE PATHOLOGY. 2002. v.81. p.86-93. Interpretive Summary: The fungus Beauveria bassiana is an environmentally friendly natural pesticide. The fungus can control many economically important insect pests. We are evaluating the potential to use this fungus to control the pecan weevil, which is a major pest of pecans. One hindrance to using the fungus against pecan weevil and other pests is that fungicides that are used to suppress plant diseases may inadvertently also suppress the beneficial fungi (such as Beauveria). We found that some strains of Beauveria are naturally resistant to fungicides. We also found that it is possible to breed for increased fungicide resistance in the laboratory. Thus, we conclude that the problem of fungicides inhibiting the use of beneficial fungi (such as Beauveria) can be overcome.
Technical Abstract: Our objectives were to determine the (1) natural variation in fungicide resistance among Beauveria bassiana strains; (2) potential to increase fungicide resistance in B. bassiana through artificial selection; and (3) stability of virulence in selected B. bassiana strains. Fungicides included dodine, fenbuconazole, and triphenyltin Hydroxide, which are commonly used in pecan and other horticultural crops. Comparison of seven B. bassiana strains indicated some are substantially more resistant to fungicides than others; a commercial strain (GHA) was less resistant than all wild strains isolated from pecan orchards. Artificial selection resulted in enhanced fungicide resistance in the GHA strain but not in a mixed wild strain. Removal of selection pressure for three passages did not reduce the enhanced fungicide resistance. Sub-culturing with exposure to fungicides did not affect the GHA strain's virulence to pecan weevil, Curculio caryae, larvae, whereas fungicide exposure increased virulence in a mixed wild population of B. bassiana.