Outdoor evaluation of Beauveria and Metarhizium fungi for mormon cricket management

The Mormon cricket (Anabrus simplex Haldeman), a flightless, shieldbacked katydid (Orthoptera: Tettigoniidae), has been a pest since the original agricultural development of the western U.S. Historically, annual agricultural losses due to Mormon cricket have amounted to millions of dollars. Current control treatments used in USDA APHIS-sponsored programs rely on carbaryl sprays or bait formulations, and diflubenzuron sprays. Non-chemical options are highly desirable in the diverse habitats in the western U.S. but there are no generally accepted entomopathogen treatments available in the U.S. During the past several years we have evaluated Beauveria bassiana strain GHA, and several isolates of Metarhizium spp. in outdoor cage trials in which the insects and their fungal infections can be affected by environmental variables, particularly temperature. While many of the tested fungi have been highly effective in the lab, where the insects cannot thermoregulate, outdoor efficacy is poorer and mortality often greatly delayed. Nevertheless, one domestic Metarhizium robertsii, DWR346, has proven promising for potential commercialization.