Abamectin compatibility with the leafminer parasitoid Diglyphus isaea

The most promising non-chemical approach for controlling Liriomyza leafminers in greenhouses is the augmentative/inoculative releases of the parasitoid Diglyphus isaea. However, the insecticide/miticide abamectin is still an important chemical control method against Liriomyza leafminers and the mite complex that attacks numerous greenhouse crops. It is not uncommon for abamectin to be applied where Diglyphus is being used for leafminer control. Consequently, there is a need to develop compatibility data for this material and Diglyphus. The effect of abamectin on D. isaea (adults and larvae) was investigated using laboratory and greenhouse experiments. Direct application and uptake of abamectin had a significant negative effect on the survival of D. isaea adult (both sexes). Abamectin residue on chrysanthemum leaves had a significant negative effect on adult D. isaea female longevity up to 5 days after application. Abamectin was lethal for D. isaea larvae when applied directly to larvae or when contaminated leafminer larvae were consumed by parasitoid larvae. However, the percent emergence of D. isaea was not affected by abamectin treatments when applied to chrysanthemum plants that contained parasitoid larvae. Moreover, the longevity of these emerged adults was not affected by abamectin applications. In light of these data, abamectin compatibility with D. isaea for leafminer control in IPM programs for greenhouses is discussed.