Residual Toxicity of Imidacloprid to Hawthorn Lace Bug, Corythuca cydoniae, Feeding on Cotoneasters in Landscapes and Containers

Abstract Cotoneasters are important and valuable landscape plants. They are severely attacked by hawthorn lace bug (Corythuca cydoniae) in landscapes and nurseries. Imidacloprid has a wide range of activity against many kinds of insect pests. We were interested in determining if cotoneasters treated with soil applications of imidacloprid in landscapes and containers remained toxic to hawthorn lace bugs for more than one growing season. Cotoneasters planted in landscapes were less damaged by lace bugs in the year that imidacloprid was applied and in the following year. We suspect that residual toxicity of leaves of cotoneasters particularly to the nymphs of lace bugs as the cause. Cotoneasters grown in containers demonstrated toxicity to lace bugs for almost 800 days after the application of imidacloprid to the soil. These data greatly extend the known period of efficacy for imidacloprid in controlling hawthorn lace bug on cotoneasters. Clearly, lace bugs are controlled for a minimum of two years. By reduc...