Entomopathogenic Hyphomycetes Associated with Gypsy Moth Larvae

Gypsy moth, Lymantria dispar, populations were sampled in four eastern North American states during 1991 and 1992 to evaluate levels of hyphomycete infection in association with releases of the Asian gypsy moth pathogen Entomophaga maimaiga. Paecilomyces farinosus was the most abundant hyphomycete species, occurring at the majority of sites, although levels of infection averaged only 4.6% (1991) and 12.2% (1992). In the plots sampled, concurrent levels of infection by E. maimaiga averaged 22.2 ± 5.5 during 1991 and 71.4 ± 12.7% during 1992 but there was no association between prevalence of P farinosus and E. maimaiga. Beauveria bassiana was the only other hyphomycete killing larvae in the field but its occurrence was rare. Verticillium lecanii and Fusarium polyphialidicum were both isolated from cadavers and could cause larval mortality during laboratory bioassays.