REDUCED TRANSMISSION OF FOREST TENT CATERPILLAR (LEPIDOPTERA, LASIOCAMPIDAE) NUCLEAR POLYHEDROSIS-VIRUS AT THE FOREST EDGE

Field experiments were conducted to determine the effect of forest edge, adjacent to clearings, in reducing the rate of transmission of nuclear polyhedrosis virus among forest tent caterpillar, Malacosoma disstria Hubner, larvae. Caterpillars on trees along a south-facing forest edge, picked up far less virus than did caterpillars on trees in the forest interior, and edge caterpillars died at a slower rate. Reduced transmission is presumed to result from the inactivation of virus by high UV radiation at the forest edge. The pattern of reduced transmission of virus at the forest edge may explain, in part, the pattern of prolonged outbreak of forest tent caterpillar in highly fragmented forests.