Incidence of fungi in natural population of Phyllophaga spp. and susceptibility of Phyllophaga anxia (LeConte) (Col., Scarabaeidae) to Beauveria bassiana and Metarhizium anisopliae
1991
Poprawski, T.J. (McGill Univ., Quebec (Canada). Macdonald College. Dept. of Entomology) | Yule, W.N.
Beauveria bassiana (Balsamo) Vuillemin, Metarhizium anisopliae (Metschnikoff) Sorokin var. anisopliae, Fusarium sp. near F. solani (Martius) Appel et Wollenweber, Cordyceps sp., Penicillium sp. and Aspergillus sp. were isolated from pest June beetles, Phyllophaga spp., in southern Quebec. The pathogenicity of the Hyphomycetes for Phyllophaga grubs was assessed by contact with sporulating fungal cultures. Grubs were moderately to highly susceptible to the fungi. Mortality was higer with B. bassiana (Bb) and M. anisopliae (Ma) than with other Hyphomycetes. The muscardines were also bioassayed against grubs using various administrative routes (oral topical, injection and soil application). Both Bb and Ma were weakly to not infectious when injected or force-fed to the grubs. Topical application of spore suspensions induced green muscardine mycosis in 64 % of second and 52 % of third instar grubs, but mortality was lower with Bb (39 and 28 %). Soil application of relatively low spore rates of Ma gave respectively 82 and 97 % control of second and third instar grubs, but a 10-fold higher spore rate of Bb achieved only 24 % control of second instars. White grubs were also susceptible to Ma applied to the soil of field plots under natural environmental conditions. The LC((50)) value for the fungus was 1.0 x 10(12) spores ha(-1) of soil. Metarhizium anisopliae is considered as a promising biocontrol agent of Phyllophaga spp.
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