Decreasing Damage to Cossus insularis (Lepidoptera: Cossidae) by Multi-year Treatment with Insecticide in Japanese Pear Orchards

Abstract

To explore effective control methods of the carpenter moth, Cossus insularis (Staudinger), we examined biological and chemical control methods in pear orchards: namely, infusion of the natural enemy nematode Steinernema carpocapsae (Weiser) into the openings of shot holes made by the larvae, and spraying the pear trees with diamide insecticide. Steinernema carpocapsae infusion into the inside of a damaged tree could significantly decrease the percentage of shot hole openings with frass discharge between before and after the infusion, regardless of the number of infusions. Furthermore, double infusion seemed to be more effective in controlling the larvae in damaged trees than single infusion. The application of flubendiamide significantly decreased the amount of feeding damage caused by newly hatched larvae just before the application, compared to that of a control plot. The combined use of S. carpocapsae infusion and diamide application for two years could significantly decrease the amount of frass discharge per damaged tree and the percentage of damaged trees.