EVALUATION OF INSECTICIDES TO REDUCE MATURATION FEEDING BY TOMICUS-PINIPERDA (COLEOPTERA, SCOLYTIDAE) IN SCOTCH PINE

Tomicus piniperda L., an economically important bark beetle in temperate regions of the Old World, was first discovered in the United States in July 1992. We evaluated effects of selected foliar insecticides on survival of beetles during maturation feeding in pine shoots. Beetles were caged on shoots of young Scotch pine, Pinus sylvestris L., before and after insecticide application in a Michigan plantation. We also determined number of shoots per tl ee infested by beetles after treatment with various foliar and ground-applied insecticides in a field study in Indiana. Shoot-feeding behavior and characteristics of shoots selected for maturation feeding were observed in both studies. Survival of beetles caged for up to 2 wk on trees treated with acephate, a mixture of acephate and bifenthrin, and imidacloprid was significantly lower than survival of beetles caged on untreated trees, regardless of whether beetles were caged before or after trees were sprayed. However, in the Indiana field study, numbers of shoots with tunnels were monitored at 4-wk intervals throughout the summer. None of the products significantly reduced the number of tunneled shoots during any interval. Most maturation feeding tunnels were found in current-year shoots, 0.45-cm diameter, located in the upper and middle canopy levels.