Unravelling the dietary ecology and traditional entomophagy of Vespula shidai in central Japan: insights from DNA metabarcoding and local practices

Abstract

Vespula shidai, a yellowjacket species, has long been reared for edible larvae and pupae in central Japan; however, limited scientific knowledge exists regarding dietary differences between wild and reared nests. In this study, DNA metabarcoding was applied to larval gut contents from 12 nests (five wild, seven reared) in central Japan to examine their dietary composition. Additionally, a questionnaire survey (n = 58) was conducted on taste perceptions of “hachinoko” (edible wasp brood) and on awareness of V. shidai’s feeding habits. DNA metabarcoding identified 324 prey species, including insects, arachnids, birds, mammals, reptiles, amphibians, and fish. Compared with reared nests, wild nests presented significantly greater diversity of wild vertebrate prey, suggesting that provisioning with human-supplied meats (e.g., chickens and deer) can partially replace natural foraging. Respondents who had wasp-rearing experience more frequently perceived taste differences between wild and reared hachinoko, often attributing these differences to the feed provided. They also recognised V. shidai’s predation on vertebrates, implying that practical engagement shapes ecological understanding and consumer preferences. These findings highlight V. shidai’s broad dietary flexibility under varying conditions of rearing and foraging. Future research could refine feeding strategies and cultural practices to sustain hachinoko as a valuable food resource while minimising its ecological impacts.