Influences of Dinotefuran Trunk Injection for Beech Sawfly Control in Nontarget Insects

The abundances of herbivorous, canopy-visiting, and predatory and parasitic insects were compared between injected and untreated trees to investigate the detrimental effects of dinotefuran trunk injection, used to control beech sawflies, on forest ecosystems. The numbers of Syneta adamsi Baly （Coleoptera: Chrysomelidae） and lepidopteran larvae, the proportion of leaves infested with Hartigiola faggalli （Monzen） （Diptera: Cecidomyiidae） galls and those deformed by Phyllaphis fagifoliae Takahashi （Hemiptera: Aphididae）, and the proportion of acorns with traces of insect-feeding were significantly lower in injected trees than in untreated trees. However, no significant differences were observed between treatments regarding the number of plant-feeding insects, such as Aphthona perminuta Baly （Coleoptera: Chrysomelidae）, the proportion of leaves with galls formed by Cecidomyiidae sp., those infested with Platyaphis fagi Takahashi （Hemiptera: Aphididae）, or the number of canopy-visiting insects, such as hemipteran, dipteran, and lepidopteran adults. The numbers of hymenopteran parasitoids and small- （≤1 cm） and medium-to-large-sized （＞1 cm） predatory cantharid beetles were lower in injected trees than in untreated trees, which could be attributed to an indirect effect due to the number of prey. These findings revealed that the effects of dinotefuran trunk injection were limited to insects that fed on leaves and seeds.