Control of leaf-footed bug Leptoglossus zonatus and shield-backed bug Pachycoris klugii with entomopathogenic fungi

The pathogenicity of three isolates of Beauveria bassiana (Bals.) Vuil. and one isolate of Metarhizium anisopliae (Metsch.) Sorok. (Deuteromycotina: Hyphomycetes) was assessed in the laboratory against adults of the leaf-footed bug Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae) and the shield-backed bug Pachycoris klugii Burmeister (Heteroptera: Scutelleridae), the two most frequent pest species in physic nut (Jatropha curcas L., Euphorbiaceae) plantations in Nicaragua. In a dipping bioassay, the median lethal concentration (LC50) of the most efficient strain, M. anisopliae NB, was determined as 4.34 x 10(6) conidia/ml for adult P. klugii. In a field trial, a scheduled high-volume spray regime using B. bassiana increased fruit yield by 28%, and was more effective than malathion of an aqueous extract of ground neem seeds. The effectiveness of M. anisopliae was further tested in field cages covering entire trees and containing a predetermined number of insects. Mineral oil-based ultra-low volume controlled droplet applications of M, anisopliae at a rate of 1 x 10(10) conidia/tree were made using hand-held Micron ULVA + sprayers. The corrected mortalities ranged from 65% in P. klugii to 94% in L. zonatus.