Toxicity of emamectin benzoate to Cydia pomonella (L.) and Cydia molesta (Busck) (Lepidoptera: Tortricidae): laboratory and field tests

Abstract

Emamectin benzoate is a novel macrocyclic lactone insecticide derived from naturally occurring avermectin molecules isolated by fermentation from the soil microorganism Streptomyces avermitilis Kim & Goodfellow. The present study aims to evaluate the toxicity of emamectin benzoate to codling moth, Cydia pomonella (L.), and oriental fruit moth, C. molesta (Busck), under laboratory and semi-field conditions. Dose response bioassays showed that emamectin benzoate had a high level of intrinsic toxicity to early-stage larvae of both species, and that contact activity might contribute significantly to mortality. In the semi-field trials, residual toxicity lasted for more than 1 week. Ovicidal activity was recorded only for C. pomonella (approximately 30%), irrespective of the concentrations tested. Field trials confirmed the efficacy of emamectin benzoate on codling moth when applied at 7 day intervals. Fruit damage, both from the first and second generations, was comparable with that on treatment with chlorpyrifos-ethyl, used as a chemical reference. Emamectin benzoate may be considered a valuable tool for the control of codling moth as a component of an IPM programme. Its collective advantages are: high efficacy, lack of cross-resistance with currently used products, control of secondary pests such as oriental fruit moth and selective toxicity that spares beneficials.