Brithys crini, the lily borer, feeds exclusively on a toxic plant, Pancratium maritimum. In most insects, the gut microbiota plays a crucial role in the nutrition and protection of the host using enzymes that are exclusive of prokaryotes. The gut microbiome of B. crini can resist the toxicity of the plant's secondary metabolites by degrading or expelling them through efflux pumps. We sequenced the 16S rRNA gene of the microbiota of 114 specimens of B. crini including two regions of the gut, the midgut and hindgut, and predicted the samples' functional profiles using the PICRUSt2 software. We examined the dynamics of the gut microbiota diversity, composition and potential functions of this insect over three consecutive years and the four corresponding seasons. We found that the insect’s core bacteria comprises a small group that belongs mainly to Proteobacteria, the most abundant phylum in Lepidoptera. Interestingly, in our samples, this phylum is the primary carrier of the enzymes related to detoxification and secondary metabolites' degradation such as alkaloids. Despite striking differences in physicochemical properties among the two gut regions evaluated, we found no significant differences regarding bacterial diversity and functional profiles. It indicates that the B. crini’s gut is colonized by generalist species that adapt to a wide range of environments. Moreover, the gut microbiota diversity and metabolic capabilities showed significant variations through the seasons and years studied. In this regard, climatic variables related to the seasons, such as temperature and precipitation, also influence the bacterial community’s diversity. These results show that the external environment exerts an unexpected influence in shaping the ecology of the gut microbiota of B. crini.

Resumen del póster presentado al XLII Congreso de la Sociedad Española de Genética, celebrado de forma virtual del 14 al 18 de junio de 2021.

This work was supported by grant PROMETEO/2018/133 (Generalitat Valenciana)-

Peer reviewed