Abstract: Effects of 11 chemical fungicides commonly used in the field on spore germination, growth rate, spore production, the extracellular protease and pathogenecity of Beauveria bassiana strain HFW-05 were determined under laboratory conditions. Almost all the tested fungicides significantly inhibited spore germination, mycelium growth, spore production and enzymatic activity at conventional concentrations. Among them, 68.75% fluopicolide propamocab hydrochloride and 50% boscalid didn't show negative effect on mycelium growth or spore germination at conventional concentrations. The 60% yl-ethyl metiram showed the highest inhibition against HFW-05 with no spore germination or mycelium growth at three test concentrations. The inhibition by most of the fungicides is concentration dependent. Bioassay results showed that 42.4% fluxapyroxad, 10% difenoconazole and 50% fludioxonil did not reduce activity of HFW-05 against Plutella xylostella 2nd instar larvae. But 25% mandipropamid, 50% boscalid, 50% dimethomorph, 68.75% fluopicolide propamocab hydrochloride, 50% kresoxim-methyl, 60% yl-ethyl metiram and 32.5% difenoconazole azoxystrobin significantly reduced the efficacy against P. xylostella larvae. 60% yl-ethyl metiram was the most harmful chemical fungicide to HFW-05, which reduced the corrected mortality of P. xylostella larvae by 49.9% in comparison with that obtained with HFW-05 only. 25% pyraclostrobin showed insecticidal activity to P. xylostella larvae with corrected mortality of 46.2%, which was increased by 20% when pyraclostrobin was mixed with HFW-05.

Key words: Beauveria bassiana, chemical fungicide, compatibility, Plutella xylostella