THE ROLE OF FUNGI IN THE CONTROL OF GRASSHOPPERS

Fungi are among the most important microbial pathogens of grasshoppers with potential for development as biological control agents. Unlike most other insect pathogens that must be ingested to initiate disease, fungi generally invade insects via the external cuticle. The most common fungi that are pathogenic to grasshoppers are Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, Sorosporella sp., and fungi in the Entomophaga grylli complex. A review of the latest information on the development of these fungi as microbial control agents of grasshoppers is presented. Species in the E, grylli complex are being used in classical biocontrol. This has resulted in controversy as there are indigenous nonpest grasshopper species that may be affected through introduction of the nonindigenous fungal strains. Beauveria bassiana and M, flavoviride are being developed for inundative control. These fungi can be mass produced and applied with equipment used for conventional pesticides. Conidia are applied either at ultralow volume in oil, as oil emulsions, or as bran-bait formulations. Field trials in Africa and North America have demonstrated significant grasshopper reductions. Improvements in formulation and inoculum targeting may further improve their efficacy.