Host Defoliation: a Possible Determinant of Gypsy Moth1 Population Quality

Gypsy moth, Lymantria dispar (L.), were reared in the field on undefoliated and artificially defoliated gray birch, Betula populifolia Marsh, and black oak, Quercus velutina Lam. The effects of defoliation resulted in reduced pupal weights, longer development time, and reduced survival. These effects occurred in the 1st year of defoliation and were magnified during the 2nd year. These data suggest that defoliation alters the nutritional quality of the host and influences the population dynamics of the insect. Differences in pupal weights and development time were noted among gypsy moths from 6 different localities reared on the same host species. Higher survival, shorter development time, and larger pupae were obtained in rearings on black oak.