Efficacy of Imidacloprid, Trunk-Injected Into <I>Acer platanoides</I>, for Control of Adult Asian Longhorned Beetles (Coleoptera: Cerambycidae)

Feeding experiments with Asian longhorned beetles (Anoplophora glabripennis (Motschulsky)) in a quarantine laboratory were used to assess the effectiveness of imidacloprid in reducing adult fecundity and survival. The beetles were fed twigs and leaves cut between June-September 2010 from Norway maples (Acer platanoides L.) in the beetle-infested area of Worcester, MA. Treated trees had been trunk-injected once with imidacloprid in spring 2010 under the U.S. Department of Agriculture-Animal and Plant Health Inspection Service operational eradication program. The 21 d LC50 value for adult beetles feeding on twig bark from imidacloprid-injected trees was 1.3 ppm. Adult reproductive output and survival were significantly reduced when beetles fed on twig bark or leaves from treated trees. However, results varied widely, with many twig samples having no detectable imidacloprid and little effect on the beetles. When twigs with > 1 ppm imidacloprid in the bark were fed to mated beetles, the number of larvae produced was reduced by 94% and median adult survival was reduced to 14 d. For twigs with < 1 ppm imidacloprid, 68% of reproductively mature mated beetles survived 21 d and 56% of unmated recently eclosed beetles survived 42 d. For twigs with < 1 ppm, beetles ingested an average of 30 nanograms of imidacloprid per day. Bark consumption was reduced at higher imidacloprid levels (> 1 ppm). When given a choice of control twigs and twigs from injected trees, beetles did not show a strong preference.