Abstract
Entomogeneous fungus, Cordyceps brongniartii SHIMAZU (=Beauveria tenella (SACC.) PETCH), is expected to be a biological control agent for the yellow-spotted longicorn beetle, Psacothea hilaris PASCOE, which is a serious pest of mulberry and fig trees. In the present investigation, we evaluated the effect of DDVP (dichrolvos) on the growth of C. brongniartii. The germination of C. brongniartii conidia was reduced and retarded on DDVP mixed SDYA or PdA medium. When C. brongniartii conidia were mixed with DDVP and applied to P. hilaris adults, the death of the beetles in mixtures of high DDVP concentrations (130ppm and above) were fewer and slower than in those of lower concentrations (63ppm and below). When C. brongniartii conidia were applied to P. hilaris, 10 days after DDVP-treatment, the death of beetles was also less and slower than that of beetles which were not treated with DDVP. From these results, it appears that DDVP inhibits the growth of C. brongniartii directly and/or indirectly. It is also suggested that the susceptibility to DDVP differs between male and female adult beetles.
