The introduction, establishment, and spread of Ormia depleta in Florida

Ormia depleta (Wiedemann) (Diptera: Tachinidae), native to Brazil, is a parasitoid of some Scapteriscus species (Orthoptera: Gryllotalpidae). It was first cultured in a laboratory in Florida in 1987. Releases of O. depleta were made against Scapteriscus mole crickets in all regions of Florida beginning in 1988. Establishment of populations was achieved at some, but not all, of the release sites. The two earliest-established populations were monitored using traps employing synthetic calling song of male Scapteriscus mole crickets, to which gravid female flies are attracted. Additionally, progeny of the released flies were trapped between 1988 and 1993 in 32 peninsular counties, including 15 counties in which no releases had been made. The most parsimonious explanation of the pathways of spread of the current population was inferred from trapping surveys, and this yielded the probable year of colonization for peninsular counties. Reports in successive years by golf course superintendents of damage by mole crickets showed that counties with O. depleta populations had significantly less damage than did yet-uncolonized counties. (C) 1996 Academic Press, Inc.