POPULATION-MODEL FOR THE GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) EGG PARASITE, OOENCYRTUS-KUVANAE (HYMENOPTERA, ENCYRTIDAE)

A model of O. kuvanae (Howard) population dynamics is developed. The model incorporates an enzyme kinetics formulation of parasitism rate with a Leslie matrix. Field data on O. kuvanae abundance from 11 plots in central Pennsylvania [USA] were used to validate the model. These data were taken from areas where gypsy moth, L. dispar (L.), population densities ranged from 66-27,830 egg masses/ha; plots were located in each of the 5 population stages: low, building, high stable, outbreak and collapse. The model accurately simulated the behavior of O. kuvanae populations. The predictions of actual parasite abundance were very good in areas with outbreak gypsy moth populations; they were progressively poorer in less dense host populations. This discrepancy indicates that the host-finding ability of O. kuvanae is less efficient in areas of low host density than in areas of high density. Inferences from the model verified the occurrence of 2 generations and a partial 3rd generation of the parasites in the late summer and autumn, and that O. kuvanae abundance is not limited by food.