Effects of Disparlure and Egg Mass Size on Parasitism by the Gypsy Moth 1 Egg Parasite, Ooencyrtus kuwanai 23

Abstract

Seven plots in Monroe CO., Pa., with a general gypsy moth, Lymantria dispar (L.), infestation were treated with disparlure. A total of 2957 egg masses was examined for numbers of eggs, parasitism by Ooencyrtus kuwanai (Howard), and embryonation. The application of disparlure had no effect on either size of egg mass or percent parasitism. There was also no effect due to the height on the tree from which the egg mass was collected. However, an interaction between height and egg mass size did affect parasitism within 0.25 m of the ground. The greatest variability in the data was attributed to plot differences. This was related to the selection of plots on the basis of level of gypsy moth infestation, and the resultant differences in egg mass size. The negative dependence of percent parasitism on number of eggs per egg mass was linearized with a natural log transformation of eggs per mass. The regression model accounted for 75% of the variation in the data. The overall weighted avg percent egg parasitism was 49.8, with a range of 26.9–81.6.