Effects of aerially applied Gypchek on gypsy moth (Lepidoptera: Lymantriidae) populations in Maryland woodlots

Moderate to high density gypsy moth, Lymantria dispar L., populations in eastern and northern Maryland were aerially treated with the nucleopolyhedrosis virus product, Gypchek. A tank mix containing Orzan LS (6% wt/vol) as a sunlight protectant, Pro Mo liquid supplement (12.5% by vol) as a feeding stimulant and humectant, and Rhoplex B60A (2% by vol) as a sticker was applied twice to nine woodlots at the rate of 18.7 liters and 1.25 x 10 super(12) polyhedral inclusion bodies per ha per application. Compared with numbers in control woodlots, this rate reduced numbers of egg masses by 98% in eastern Maryland, and by 80% in northern Maryland. Differences in defoliation between sprayed and control woodlots in either area were not significant.