Trichogramma wasps are highly effective biological control agents, offering an environmentally sustainable solution for pest management through their parasitism of insect eggs. This study evaluates the parasitism performance of six Trichogramma species—T. dendrolimi, T. chilonis, T. leucaniae, T. ostriniae, T. japonicum, and T. pretiosum—on five treatments of Eri silkworm (ES) eggs, a potential alternative to the large eggs of Antheraea pernyi for mass rearing. The ES egg treatments included the following: manually extracted, unfertilized, and washed eggs (MUW); naturally laid, unfertilized, and washed eggs (NUW); naturally laid, unfertilized, and unwashed eggs (NUUW); naturally laid, fertilized, and washed eggs (NFW); and naturally laid, fertilized, and unwashed eggs (NFUW). The results demonstrate that all Trichogramma species, except T. japonicum, successfully parasitized ES eggs across all treatments. Notably, washed eggs consistently supported higher parasitism and emergence rates compared to unwashed eggs, while unfertilized eggs outperformed fertilized eggs in these metrics. Among the treatments, unfertilized and washed eggs (MUW and NUW) exhibited the shortest pre-emergence time and the highest number of emerged adults, with no significant differences in female progeny ratios across most species. A striking exception was T. dendrolimi, which showed a significantly higher female offspring ratio in the MUW treatment. These findings highlight that MUW eggs of ES are a highly suitable alternative host for the mass production of Trichogramma wasps. This study provides critical insights for optimizing host egg treatments to enhance the efficiency of Trichogramma-based biological control programs.

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.

Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae) are pupal parasitoids capable of successfully developing on Drosophilidae species, including the invasive pest Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). Both parasitoids are considered potential biological control agents for managing D. suzukii. We conducted a long-term laboratory rearing study to assess whether different rearing host species, specifically D. suzukii and Drosophila melanogaster Meigen (Diptera: Drosophilidae), influence the parasitoids’ preference for D. suzukii pupae at different developmental stages. In no-choice tests, T. drosophilae reared on either D. suzukii or D. melanogaster exhibited a preference for parasitizing younger D. suzukii pupae over older ones. In contrast, P. vindemiae reared on both host species did not show a significant difference in parasitism rates across D. suzukii pupal stages. Additionally, there were no significant differences in the performance of T. drosophilae and P. vindemiae after 10 generations of rearing on D. melanogaster when tested on D. suzukii pupae, compared to those reared on D. suzukii. These results suggest that long-term rearing on an alternative host does not alter the host stage preference of these parasitoids for D. suzukii.