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United States Department of Agriculture

Agricultural Research Service

Title: Disease Interactions in Gypsy Moth Populations in Sw Virginia Usa

Authors
item Webb, Ralph
item White, Geoffrey
item Thorpe, Kevin
item Tally, S - ROCKBRIDGE CO BYP MOTH PR

Submitted to: Entomology International Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 29, 1996
Publication Date: N/A

Technical Abstract: Southwestern Virginia is currently experiencing its first cycle of defoliation from the gypsy moth, which has recently invaded this area. As gypsy moth populations rise, natural enemies are moving into the area, including the gypsy moth nuclear polyhedrosis virus (NPV). NPV typically occurs at low levels until gypsy moth populations rise; then, NPV becomes the dominant factor leading to gypsy moth population collapse. An intriguing new (to North America) disease of gypsy moth is the fungus Entomophaga maimaiga, which was introduced into SW Virginia in 1991, and which is now widely established there. In 1995, we monitored gypsy moth populations in 33 woodlots near Lexington, VA, for the presence of the two pathogens. Gypsy moth populations in the woodlots varied from very sparse to high. Monitoring was most intense in the 5 blocks with the highest gypsy moth population density. Larvae were collected weekly, and those dying within 7 days were examined by light microscopy to identify the pathogen species involved. Also, burlap band larval counts were made weekly. The virus was strongly density dependent, being confirmed only from woodlots with higher density gypsy moth populations. In contrast, the presence of the fungus was confirmed from gypsy moth cadavers found in woodlots containing very sparse (less than 1 life stage found per burlap-band larval trap) gypsy moth populations. All higher density plots had extensive fungal induced mortality, but this failed to prevent a distinct second-wave NPV occurrence.

Last Modified: 8/22/2014
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