Proc. Natl. Acad. Sci.
In North America there are two generally recognized pathotypes (pathotypes 1 and 2) of the fungus Entomophaga grylli which show host-preferential infection of grasshopper subfamilies. Pathotype 3, discovered in Austra- lia,hasabroadergrasshopperhostrangeandwasconsidered to be a good biocontrol agent. Between 1989 and 1991 patho- type3wasintroducedattwofieldsitesinNorthDakota.Since resting spores are morphologically indistinguishable among pathotypes, we used pathotype-specific DNA probes to con- firm pathotype identification in E. grylli-infected grasshop- pers collected at the release sites in 1992, 1993, and 1994. In 1992, up to 23% of E. grylli-infected grasshoppers of the subfamilies Melanoplinae, Oedipodinae, and Gomphocerinae were infected by pathotype 3,with no infections >1 km from the release sites. In 1993, pathotype 3 infections declined to 1.7%. In 1994 grasshopper populations were low and no pathotype3infectionswerefound.Thefrequencyofpathotype 3 infection has declined to levels where its long-term survival in North America is questionable. Analyses of biocontrol releases are critical to evaluating the environmental risks associatedwiththeseecologicalmanipulations,andmolecular probesarepowerfultoolsformonitoringbiocontrolreleases.
Bidochka, M.J., S.R.A. Walsh, M.E. Ramos, R.J. St. Leger, J.C. Silver and D.W. Roberts. 1996. Fate of biological control introductions: Monitoring an Australian fungal pathogen of grasshoppers in North America. Proc. Natl. Acad. Sci. 93: 918-921.