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 strainís virulence to pecan weevil, Curculio caryae, larvae, whereas fungicide exposure increased virulence in a mixed wild population of B. bassiana.
Species 1: Deuteromycotina Hyphomycetes Beauveria bassiana
Species 2: Coleoptera Curculionidae Curculio caryae (pecan weevil)
Keywords: biological control, genetic improvement
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