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

Tomicus piniperda L., an economically important bark beetle in tempera te regions of tile Old World, was first discovered in the United State s in July 1992. We evaluated effects of selected foliar insecticides o n survival of beetles during maturation feeding in pine shoots. Beetle s were caged on shoots of young Scotch pine, Pinus sylvestris L., befo re and after insecticide application in a Michigan plantation. We also determined number of shoots per tl ee infested by beetles after treat ment with various foliar and ground-applied insecticides in a field st udy in Indiana. Shoot-feeding behavior and characteristics of shoots s elected for maturation feeding were observed in both studies. Survival of beetles caged for up to 2 wk on trees treated with acephate, a mix ture of acephate and bifenthrin, and imidacloprid was significantly lo wer than survival of beetles caged on untreated trees, regardless of w hether beetles were caged before or after trees were sprayed. However, in the Indiana field study, numbers of shoots with tunnels were monit ored at 4-wk intervals throughout the summer. None of the products sig nificantly reduced the number of tunneled shoots during any interval. Most maturation feeding tunnels were found in current-year shoots, 0.4 5-cm diameter, located in the upper and middle canopy levels.