SUBLETHAL IMPACTS OF AZADIRACHTIN ON THE REPRODUCTIVE STRUCTURE OF SCLERODERMA SICHUANENSIS (HYMENOPTERA: BETHYLIDAE)

Abstract

Azadirachtin, a natural insecticide derived from neem, is well known for its low toxicity to mammals and its selective effectiveness against pest insects. Nonetheless, the sublethal effects on beneficial parasitoid wasps have not been thoroughly examined. This research explored the impact of azadirachtin on the genital complex morphology of the ectoparasitic wasp Scleroderma sichuanensis. Adult females were subjected to six different concentrations (10, 25, 50, 75, 100, and 150 mg/mL) in a controlled laboratory environment. We conducted a morphometric analysis of ovipositor length and width in 30 individuals per treatment. A concentration-dependent decrease in both measurements was noted, with the highest concentration (150 mg/mL) leading to a reduction of 72.3% in ovipositor length and 73.5% in width compared to the control group. The 50 mg/mL concentration, which is close to the recommended application rates in the field, resulted in reductions of 36.7% and 32.4%, respectively. These results indicate that although azadirachtin is regarded as environmentally friendly, it may still present sublethal threats to non-target hymenopteran natural enemies. Therefore, the incorporation of azadirachtin into pest management strategies should consider these morphological changes to maintain biological control functions.