Differential influence of temperature on the toxicity of three insecticides against the codling moth Cydia pomonella (L.) and two natural enemies

Abstract

Insecticide toxicity may strongly vary with temperature, and interspeci c differences have been commonly reported for this relationship. A differential in uence of temperature on insecticide toxicity between pests and their natural enemies may have important consequences on biological control in a global warming context. This study aimed to investigate cross effects between temperature and three insecticides -i.e., chlorantraniliprole, emamectin and spinosad -on the mortality of a major pest in orchards, Cydia pomonella L., and two of its natural enemies in southern France, the predatory earwig For cula auricularia L. and the introduced parasitoid Mastrus ridens Horstmann. We observed a decreased e ciency of emamectin and spinosad with increasing temperature on mortality of codling moth, while no in uence of temperature on chlorantraniliprole e cacy was observed. Increasing temperatures increased the toxicity of all insecticides against M. ridens and only for emamectin on F. auricularia. This study provides essential insight to make recommendations for using these insecticides in combination with two natural enemies to control the codling moth in a warming world. Our results suggest that the use of spinosad may become sub-optimal under higher temperatures. In contrast, chlorantraniliprole should remain suitable under warmer climatic conditions to control C. pomonella, conserve F. auricularia and facilitate the establishment of M. ridens. For conservation biological control relying on F. auricularia, alternating use of emamectin during early spring, when its toxicity is the lowest on this natural enemy, and chlorantraniliprole during summer could limit resistance risks in codling moth populations and reduce the insecticides' impact on the populations of natural enemies.

Current Status of the Main Olive Pests: Useful Integrated Pest Management Strategies and Genetic Tools

“…Until recently, one of the most promising key advantages of spinosad in IPM is its selectivity and low toxicity to beneficial insects and non-target organisms, such as bees, butterflies, and predators like ladybugs and lacewings. However, spinosad has an undesirable effect on populations of natural enemies of the olive fly, mainly on predatory arthropods inhabiting the tree canopy but also pollinators such as Apis mellifera or natural enemies of some other pests [172][173][174][175][176]. Nevertheless, sustainable olive grove management holds the potential to alleviate this adverse impact, as it distinctly enhances various soil quality parameters, encompassing the abundance and diversity of microbial and pedofaunal communities [160,177,178].…”