PREDATION OF GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) PUPAE BY INVERTEBRATES AT LOW SMALL MAMMAL POPULATION-DENSITIES

A census of small mammal populations was taken, and freeze-dried gypsy moth, Lymantria dispar (L.), pupae were placed at 6 sites near the le ading edge of moth spread into the southeastern United States. Pupal p redation was monitored during 3 consecutive nights and a significant r elationship between the number of live small mammals and predation was observed. There was a significant inverse relationship between verteb rate and invertebrate predation levels. Pupal predation by vertebrates increased as small mammal density increased,; but invertebrate predat ion apparently decreased with increasing small mammal density. At all sites, pupae were preyed on beginning the Ist night of exposure, sugge sting that the native generalist predator complex should exhibit no ti me lag in recognizing and accepting gypsy moth pupae as a new food ite m. The percentage of intact pupae preyed on by vertebrates increased f rom day 1 to day 2 but then declined on day 3. In contrast, invertebra te predation increased from day 1 to day 2 and remained at the higher rate on day 3. These observations are discussed in relation to behavio ral characteristics of the predator populations.