Screening two entomopathogenic fungal strains with high virulence against Asia citrus psyllid, Diaphorina citri

Objective To screen entomopathogenic fungal strains with high virulence against Asia citrus psyllid (ACP), Diaphorina citri Kuwayama, and to provide a basis for development of microbial pesticide against ACP.

Method The growth and sporulation rates of five Beauveria bassiana strains numbered A to E and five Isaria fumosorosea strains numbered A to E, and the mortality rates of ACP after infected by these ten fungal strains were investigated.

Result The spores quantity of five B. bassiana strains were significantly different after cultured for 10 days, strain E had the largest spores quantity(3.78×10⁸ mL^-1) and strain A had the least spores quantity(7.96×10⁷ mL^-1). There was significant difference of spores quantity between strain E and strain A. There was no significant difference among the mortality rates of 2-3 instar ACP nymphs seven days after the spray of 1×10⁶ mL^-1 B. bsssiana fungal spores, and the highest mortality rate (78.0%) was found in the strain A treatment, followed by the strain E treatment (77.0%). For five I. fumosorosea strains, the spores quantity after cultured for 10 days, strain B had the highest sporulation rate (6.04×10⁸ mL^-1) and strain E had the least spores quantity(6.28×10⁷ mL^-1). There was significant difference of spores quantity between strain B and strain E. The mortality rates of 2-3 instar ACP nymphs seven days after the spray of 1×10⁶ mL^-1 I. fumosorosea fungal spores were higher than the control group except strain D. ACP infected by strain B had the highest mortality rate(81.0%).

Conclusion B. bassiana strain E and I. fumosorosea strain B are considered with high virulence against ACP and can be potentially used for biological control of ACP.