Toxicity of crude toxin protein produced by Cordyceps fumosorosea IF-1106 against Myzus persicae (Sulze)

Abstract

The entomopathogenic fungus Cordyceps fumosorosea IF-1106 is a potential biocontrol agent with high pathogenicity to the aphid Myzus persicae. We extracted the crude toxin protein from a liquid culture broth of an isolated C. fumosorosea strain using the ammonium sulfate precipitation method, and its toxicity to Myzus persicae was measured by injection, oral exposure, and topical exposure. The crude toxin protein of C. fumosorosea had insecticidal activity against M. persicae. Body cavity injection and oral exposure had significantly higher insecticidal activity against adults than contact sprays. The highest cumulative corrected mortality of adults after injection was 81.85 ± 13.45 %, and the highest cumulative corrected mortality of adults after ingestion was 85.45 ± 11.88 %. The proportion of plasmatocytes in adult blood lymphocytes reached the highest at 3 days after injection and feeding, and the proportion of granulocytes was the highest at 2 days after injection and feeding. These data confirmed the toxicity of the crude toxin protein of C. fumosorosea toxin to M. persicae and helped clarify the pathogenic mechanism of the strain. Population management of M. persicae may be possible by using a natural toxic compound produced by C. fumosorosea that is selective to this pest species.