Nest Architecture Drives Sex-Specific Emergence Success in a Predator Wasp (Hymenoptera, Vespidae, Discoelius wangi)

Predatory insects play a crucial role in maintaining ecosystem balance. Among them, members of the subfamily Zethinae, as natural enemies of herbivorous pests, have reproductive success closely linked to nest architecture, as this limits their prey items. We set up trap nests for Discoelius wangi Yamane, 1996 in a subtropical forest in southwestern China to investigate the effects of nest architecture parameters (number of intercalary cells, nest diameter, and vestibule length) on the number of brood cells, the quantity of male and female offspring, and emergence rate via generalized linear models and hierarchical partitioning. The results showed that for the number of nest cells, only the number of intercalary cells had a significant positive effect. For the quantity of male and female offspring, nest diameter, and the number of intercalary cells had significant positive effects on female offspring, while males were only significantly positively affected by the number of intercalary cells. For emergence rates, female emergence rate was marginally significantly affected by nest diameter, male emergence rate was marginally significantly affected by the number of intercalary cells, and total emergence rate was significantly influenced by vestibular length and the number of intercalary cells. This study indicates that D. wangi can adjust its nest characteristics to achieve precise regulation of reproductive performance. The results not only enhance our understanding of how human activities affect predatory insects in forest ecosystems but also provide a scientific basis for developing effective conservation and utilization strategies.