Differential chemical hazards of common insecticides to Eupelmidae parasitoids: An ecological risk assessment for integrated pest management in forest ecosystems

Eupelmidae parasitoids (Anastatus and Mesocomys spp.) are crucial for biological pest control, yet their ecological function may be compromised by insecticide exposure within integrated pest management programs. We evaluated the lethal and sublethal hazards of five widely used insecticides (beta-cypermethrin, avermectin, imidacloprid, matrine, and chlorbenzuron) on four parasitoid species. Beta-cypermethrin exhibited high toxicity to M. albitarsis and M. trabalae, causing 100 % mortality within 72 h, while A. japonicus and A. meilingensis showed significantly greater tolerance. Hazard quotient (HQ) analysis confirmed the high risk of beta-cypermethrin to Mesocomys species (HQ > 1), whereas Anastatus species (HQ < 1) were less affected. In contrast, matrine and chlorbenzuron produced minimal adverse effects on survival, parasitism, emergence, or sex ratio across all tested species. Further experiments revealed that A. meilingensis maintained survival rates exceeding 70 % following exposure to other pyrethroids, whereas survival of M. albitarsis and M. trabalae declined below 50 %, indicating pronounced genus-specific sensitivity to chemical stressors. Consistent patterns were observed in semi-field cage experiments, in which A. meilingensis exhibited higher survival under beta-cypermethrin exposure than the other parasitoids. Overall, the study highlights the clear contrast in insecticide tolerance between Anastatus and Mesocomys species, with A. meilingensis emerging as a more resilient candidate for biological control in insecticide-treated environments. Our findings support the use of selective insecticides (e.g., matrine and chlorbenzuron) to conserve vulnerable parasitoids while maintaining pest control efficacy, thereby promoting sustainable forest management.