Comparative lethal and sublethal effects of sulfoxaflor and acetamiprid on Cryptolaemus montrouzieri (Coleoptera:...

Following regulatory restrictions on several neonicotinoids, sulfoxaflor, a sulfoximine insecticide proposed as a replacement, has been reported as highly effective against a broad range of sap-feeding pests. However, its impact on key biological control agents, such as the widely used mealybug destroyer Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae), remains insufficiently investigated. In this study, we assessed the lethal and sublethal effects of recommended field rates of sulfoxaflor on larvae and adults of C. montrouzieri through direct spray treatments and exposure to fresh residues on grapevine plants, comparing its impact with that of acetamiprid. Laboratory bioassays evaluated mortality, development, fecundity, fertility, offspring survival, and demographic parameters following IOBC guidelines and population modeling. Our results show that sulfoxaflor caused significantly lower mortality than acetamiprid, with minimal effects on larvae and no adverse effects on adults. Demographic modeling further indicated that the demographic performance of C. montrouzieri populations was not negatively affected by sulfoxaflor, while the impact of acetamiprid on the predator was primarily driven by high short-term mortality, with only marginal contributions from changes in reproductive performance. According to IOBC classification, sulfoxaflor was categorized as slightly harmful (class 2) for larvae and harmless (class 1) for adults, indicating potential compatibility with IPM programs involving augmentative releases of C. montrouzieri. Our findings highlight the value of integrating demographic modeling into IOBC assessments to improve ecotoxicological risk evaluation of insecticides on biological control agents.