Diet breadth shapes gut microbiota in the invasive hornet <i>Vespa velutina</i>

Abstract Diet is a major driver of gut microbiota composition in insects, shaping digestive processes, metabolism, and adaptation to new environments. In invasive species such as Vespa velutina nigrithorax , trophic flexibility may be linked to microbial plasticity, potentially facilitating its ecological success. However, the relationship between diet and gut microbiota in this species remains poorly understood. Here we analyse both the gut microbiota and the diet of V. velutina larvae from seven nests in Mallorca (Balearic Islands, Spain) using DNA metabarcoding approaches. Our results reveal a significant positive correlation between diet richness and microbial diversity, suggesting that variation in prey consumption contributes to shaping gut microbial communities. Firmicutes (49.39%) and Actinobacteriota (31.72%) were the most abundant bacterial phyla inside V. velutina nests. Additionally, we identified 26 significant correlations between dietary and microbial components, with Actinobacteriota (9) and Lepidoptera (18) being the microbial phylum and insect order showing the highest number of significant associations. These findings indicate that V. velutina microbiota responds dynamically to dietary inputs, potentially enhancing digestive efficiency and adaptability to novel environments. Overall, our study underscores the importance of gut microbiota–diet associations and provides new insights into microbial mechanisms that may contribute to the invasive success of V. velutina .