Landscape‐Wide Metabarcoding Shows Interactions Among the Gut Microbiome and Pollen Diversity in the Invasive Bumblebee, <scp> <i>Bombus terrestris</i> </scp>

Gut microbial communities can facilitate traits that are essential for invasive species survival in novel environments. Despite the global plethora of invasive social insect species, the role of the gut microbiome in colonisation success under novel dietary and environmental conditions is little known. The introduction of the European buff-tailed bumblebee, <i>Bombus terrestris</i>, to the island of Tasmania (Australia) ~30 years ago is of ecological concern due to its negative impacts on native vegetation and endemic bees. Here, we investigate how the gut microbiota of <i>B. terrestris</i> workers is affected by corbicular pollen diversity and environmental variation across diverse landscapes in an invaded island system. <i>B. terrestris</i> female workers were sampled from 19 sites across Tasmania, for which environmental data for seven variables were extracted. Using 16S rRNA and ITS2 metabarcoding on gut samples and foraged pollen, respectively, we examine how the gut microbiota of <i>B. terrestris</i> is influenced by pollen diversity, environmental variables and their interactions. Gut bacterial community composition was significantly predicted by site annual precipitation and the percentage of pasture, which each explained 9% of the variation. Gut bacterial diversity was also explained by precipitation and pasture (40% and 30% of the variation, respectively). Furthermore, a positive interaction between annual precipitation and annual temperature significantly predicted site gut bacterial diversity. The interaction effect of pollen diversity and summer wind velocity was also positively related to gut bacterial diversity. Our findings contribute to understanding how interactions between the local environment and pollen diet affect the bee gut microbiome and thus the health and success of invasive pollinators.