Introduction and establishment of Entomophaga maimaiga, a fungal pathogen of gypsy moth (Lepidoptera: Lymantriidae) in Michigan
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Environmental Entomology 24(6):1685-1695
In 1991, late instars of gypsy moth, Lymantria dispar (L.), were sampled and diagnosed for infections of the pathogenic fungus Entomophaga maimaiga Humber, Shimazu & Soper and for gypsy moth nuclear polyhedrosis virus (NPV) at 50 sites in Michigan. Approximately 1,500 larvae were collected and reared from these sites, and no infections of E. maimaiga were detected. From 1991 to 1993, we tested the efficacy of 2 inoculative-release methods for E. maimaiga in replicated plots at 3 research sites by relocating soil containing E. maimaiga resting spores from Massachusetts to Michigan or by releasing inoculated larvae onto boles of trees. In the 2nd yr after introduction, E. maimaiga became established (9-40% infection) where both inoculation methods were used, and a low level of infection was detected in control plots (0.5-2.4%). In the 3rd yr, epizootics of E. maimaiga occurred at all 3 research sites, with the incidence of infection ranging from 20 to 99% in both treated and control plots. Infection levels were correlated with precipitation and relative humidity ≥90% for 2 wk preceding larval sampling. In 1993, egg mass densities at the 3 E. maimaiga study sites averaged 3- to 10-fold lower than in adjacent oak forest. We found that it is easy to introduce E. maimaiga to new locations even in the midst of an epizootic of gypsy moth NPV and that E. maimaiga reduces gypsy moth populations to levels lower than that caused by NPV alone.
KeywordsLymantria dispar Entomophthorales Entomophaga maimaiga nuclear polyhedrosis virus biological control
Smitley, D. R.; Bauer, L. S.; Hajek, A. E.; Sapio, F. J.; Humber, R. A. 1995. Introduction and establishment of Entomophaga maimaiga, a fungal pathogen of gypsy moth (Lepidoptera: Lymantriidae) in Michigan. Environmental Entomology 24(6):1685-1695