RELATIONSHIPS BETWEEN DIFFERENT SAMPLING PROCEDURES FOR THE GYPSY MOTH, PORTHETRIA DISPAR (LEPIDOPTERA: LYMANTRIIDAE) AND ITS NATURAL ENEMIES

Abstract

AbstractA variety of field sampling procedures were used to estimate population levels of the gypsy moth, Porthetria dispar (L.) (Lepidoptera: Lymantriidae), and the following natural enemies: Apanteles melanoscelus (Ratzeburg) (Hymenoptera: Braconidae), Blepharipa scutellata (Robineau-Desvoidy) (Diptera: Tachinidae), and Calosoma sycophanta (L.) (Coleoptera: Carabidae). Regression analyses indicated, among other things, that gypsy moth egg mass counts were not good indicators of tree defoliation, but that defoliation and number of gypsy moth larvae on branch terminals were correlated. Estimates of adult abundance of A. melanoscelus and B. scutellata were negatively correlated with estimates of numbers of immature parasitoids. Numbers of gypsy moth larvae parasitized by A. melanoscelus were positively correlated with numbers of A. melanoscelus cocoons sampled. Numbers of adult C. sycophanta were not correlated with larval numbers of this insect. It was concluded from these results that the procedures used to estimate numbers of natural enemy adults were not entirely adequate, but may be useful for supplementing other sampling methods.