Effective control of Frankliniella occidentalis by Metarhizium anisopliae CQMa421 under field conditions

Annual economic losses of eggplant due to western flower thrips ( Frankliniella occidentalis ) infestations are considerable. F. occidentalis is difficult to control due to rapid proliferation rates and resistance to chemical insecticides. A more effective biological control strategy is urgently required. To assess the potential efficacy of M. anisopliae CQMa421 in the biological control of F. occidentalis on eggplant, we evaluated its virulence and insecticidal activity in the laboratory and field. The laboratory results indicated that the LT 50 of M. anisopliae CQMa421 against F. occidentalis at 2 × 10 7 conidia/ml was 5.5 days. The results from the experimental field trial showed that a single spray of M. anisopliae CQMa421 reduced thrips by 50–70% compared to the control; this was significantly lower than for the chemical insecticide imidacloprid. However, the results from demonstration field trials where consecutive sprays were made indicated that M. anisopliae CQMa421 controlled the pests at a level equivalent to that obtained with a chemical insecticide. The findings clearly demonstrated the feasibility of using M. anisopliae CQMa421 as an alternative to chemical insecticides in the control of F. occidentalis under field conditions.