EFFICACY OF GROUND APPLICATION OF THE GYPSY-MOTH (LEPIDOPTERA, LYMANTRIIDAE) NUCLEOPOLYHEDROSIS VIRUS PRODUCT, GYPCHEK

Low and moderate density gypsy moth (Lymantria dispar L.) populations in eastern Maryland were treated with the nucleopolyhedrosis virus product, Gypchek, using ground hydraulic equipment. A tank mix containing Orzan LS-50 (12% by vol) as a sunlight protectant, and Rhoplex B60A (2% by vol) as a sticker, was applied to six woodlots at the rate of 378 liters and 2.5 x 10(12) polyhedral inclusion bodies per ha. This rate reduced numbers of egg masses by 81% compared with numbers in six control woodlots. Larval mortality was significantly higher in treated than in control woodlots, but defoliation differences between sprayed and control woodlots were not significant. Foliage collected 14 d after spray retained sufficient activity to kill up to 38% of gypsy moth larvae in laboratory bioassays.