Lethal, sublethal, and transgenerational effects of insecticides on Closterocerus coffeellae (Ihering) (Hymenoptera: Eulophidae), an important parasitoid of coffee leaf miner

The integration of chemical and biological control for the coffee leaf miner Leucoptera coffeella within integrated pest management requires assessing insecticide impacts on the key parasitoid, Closterocerus coffeellae. This study evaluated the lethal effects of chlorpyrifos, isocycloseram, ethiprole, and chlorantraniliprole on C. coffeellae females via ingestion, topical application, and residual contact, and the sublethal and transgenerational effects of chlorantraniliprole on C. coffeellae. Field-collected adults were exposed to maximum label rates. Chlorpyrifos, isocycloseram, and ethiprole caused high acute mortality across all routes, classifying them as harmful. In contrast, chlorantraniliprole was harmless. In bioassays evaluating the sublethal effects of chlorantraniliprole on the parasitoid, the insecticide significantly impaired their parasitism behavior. Females exposed to chlorantraniliprole via ingestion showed altered parasitism patterns, including reduced searching events, searching time, parasitism rate and oviposition attempts. The residual contact exposure caused reduced searching time, and oviposition attempts. Ingestion exposure reduced walking speed and distance. Transgenerational effects of the chlorantraniliprole in the first generation of females exposed via ingestion manifested as a prolonged pupal duration, while sex ratio, egg-incubation + larvae duration, and first generation survival were unaffected. Our results demonstrate that chlorpyrifos, ethiprole, and isocycloseram are incompatible with C. coffeellae due to high acute lethality across all exposure routes. Although chlorantraniliprole was classified as "harmless," the compound altered parasitism and locomotor behavior and prolonged the pupal stage of first-generation females, effects that have never been reported for parasitoids of the coffee leaf miner. These findings serve as an urgent warning to coffee farmers: current practices may lead to a decline in parasitoid populations. Reversing this trend requires a shift toward sustainable practices that prioritize selective, parasitoid-compatible molecules, a crucial step for the long-term sustainability of the coffee agroecosystem.