A laboratory assessment of the potential of selected entomopathogenic fungi to control the green leafhopper Empoasca decipiens Paoli (Homoptera: Cicadellidae).

Objective: The present study was conducted to evaluate the effect of selected entomopathogenic isolates on various nymphal stages of the green leafhopper Empoasca decipiens Paoli . Methodology and results: The efficacy of 5 fungal isolates from the genera of Beauveria, Verticillium, Paecilomyces and Metarhizium to the green leafhopper, E. decipiens nymphs, was tested under laboratory conditions. A single exposure concentration (1 x 107 conidia/ml) assays for each isolate were first conducted by contact with treated disc leaf for 5 min. These were followed by multiple-concentration assays on three of the most pathogenic isolates using four test concentrations ranging from 1 x 10 3 to 1 x 10 6 conidia/ml. All isolates proved to be highly virulent to late fifth-instar nymphs of E. decipiens, with mortality ranging from 60 to 98% and the mean survival time (MST), from 4.30 to 6.09 days. Among the tested isolates, three isolates, M. anisopliae (Ma43), B. bassiana (Bba113) and P. fumosoroseus (Pfr12) were the most pathogenic to the nymphs, resulting in significantly higher mortality and lower MST values. In the multiple-concentration assays, nymphal mortality was dose-dependent. The LC 50 values ranged from 0.8 to 5.0 x 10 5 conidia/ml with the third- and fifth-instar nymphs being more susceptible than the first-instar. All tested strains were able to complete their life cycle by forming conidiospores on the dead insects; in general one to two days after the host had died. Conclusion and application of findings: Our current study has identified virulent isolates of M. anisopliae, P. fumosoroseus and B. bassiana, the first two being commercially available, and that are good candidates for further development as biological control agents for E. decipiens.