Pathogen Reservoirs as a Biological Control Resource: Introduction of Entomophaga maimaiga to North American Gypsy Moth, Lymantria dispar, Populations

The fungal pathogen Entomophaga maimaiga Humber, Shimazu & Soper does not occur in all areas currently colonized by its hosts, larvae of the gypsy moth, Lymantria dispar (L.). Methods for introducing this fungus to novel areas using environmental manipulation and different fungal life stages were compared. In plots where overwintered resting spores were introduced and regularly moistened, over 90% of larvae became infected. The majority of fungal mortality occurred in later instars. All introduction methods resulted in infection levels of >20%. Bioassays of resting spores in soil and bark demonstrated infection throughout the period that gypsy moth larvae were present in the field. Our results suggest that resting spores probably infect larvae throughout the season and are important to epizootic development. (C) 1991 Academic PRESS, Inc.