Metagenomic analysis of developmental-category-associated fungal communities in the gut contents of Achatina fulica, an intermediate host of Angiostrongylus cantonensis

Abstract

The invasive giant African snail ( Achatina fulica ) poses serious agricultural and ecological threats and serves as an important intermediate host of the zoonotic parasite Angiostrongylus cantonensis , which causes human eosinophilic meningitis. While its gut bacterial microbiome has been extensively characterized, the gut mycobiome remains largely uncharacterized. In particular, variations in gut fungal communities across developmental stages remain unknown, limiting our understanding of the A. fulica gut holobiont. In November 2025, giant African snails were collected from Guangzhou, Guangdong Province, China. Genomic DNA was extracted from the gut contents of the collected snails. Metagenomic sequencing was conducted to characterize variations in the gut mycobiota across different snail sample types. Metagenomic sequencing of 18 snail gut samples across three developmental stages showed lower fungal alpha diversity in adults than in juveniles, whereas PCoA visualized differences in community composition among developmental categories and PERMANOVA confirmed that these differences were statistically significant. Ascomycota dominated the mycobiome, with developmental-category-associated differences in taxonomic composition. LEfSe and DESeq2 identified differentially abundant taxa associated with developmental categories, while SIMPER analysis identified several taxa contributing to the observed dissimilarity, including Synchytrium taraxaci , Aspergillus flavus and Cladosporium cladosporioides . These taxa are interpreted as contributors to community dissimilarity rather than as causal drivers of developmental-category-associated differences. Co-occurrence networks analysis identified six highly connected taxa ( Hanseniaspora uvarum , Apiospora montagnei , Aureobasidium thailandense , Colletotrichum aenigma , Truncatella angustata , and Calonectria ilicicola ) within the inferred fungal association network. Gut fungal community composition differed significantly among the sampled developmental categories of A. fulica , although the cross-sectional design does not establish that the host development itself causes these differences. The identified developmental-category-associated and highly connected taxa provide a baseline for gut mycobiota ecology and a foundation for future controlled studies investigating their functional roles and potential relevance to A. cantonensis infection.