Potential Functions and Transmission Dynamics of Fungi Associated with Anoplophora glabripennis Across Different Life Stages, Between Sexes, and Between Habitats

The fungi residing in the gut and associated habitats play a crucial role in the growth and development of <i>Anoplophora glabripennis</i> (Motschulsky) (Coleoptera: Cerambycidae), a wood-boring pest. Yet, how they are acquired and maintained across generations, and their respective roles throughout the life cycle, remain unknown. To this end, we used high-throughput ITS sequencing analysis to characterize the fungal composition and diversity associated with <i>A. glabripennis</i> across three different life stages, between sexes, and between its habitats. Overall, the fungi composition was stage specific, with adult gut communities being more diverse than those of larvae and eggs. Male fungal communities differed significantly, while frass and female communities were more similar to each other. The top 10 most abundant genera were investigated, with <i>Fusarium</i> consistently observed in all samples and exhibiting the highest overall abundance. Function predictions revealed the presence of potentially beneficial fungi that may support <i>A. glabripennis</i> invasion across all groups. Additionally, we observed complex network structures in the fungal communities associated with eggs and males, and stronger positive correlations in those of eggs and newly hatched larvae. Source tracking analysis suggested that these fungi were vertically transmitted, following a transmission pathway of 'female gut-frass-egg-larval gut', occurring via frass deposited in oviposition sites. Our findings provide a nuanced understanding of the intricate interactions among plants, insects, and fungi, shedding light on the acquisition, maintenance, and roles of gut-associated fungi in <i>A. glabripennis</i>.