The effects of direct and indirect antibiotic-induced gut dysbiosis on bumblebee survival and pathogen infection prevalence [project proposal]

There are various defence mechanisms against diseases, including gut bacteria. The gut bacteria in a healthy microbiome can prevent pathogen colonisation and thus protect against diseases. Recent research indicates that disturbing the balance of the gut microbial community, as happens when pollinators are exposed to antibiotics while foraging, may reduce survival and increase pathogen susceptibility.

However, the mechanisms behind the negative impact of antibiotic exposure are still unclear. They could stem from direct antibiotic toxicity or alternatively might be a consequence of the antibiotics disrupting the gut microbial community, thereby interfering with the positive effects of gut microbiota on the host. In this experiment, I aim to unravel the interactions between an antibiotic’s direct toxicity and its influence on the microbiome.

Bumblebees aquire their microbiome from conspecifics shortly after emergence. Naive bumblebees extracted directly from their cocoons that have not yet received gut microbiota from other colony members will be fed with microbiome inoculum prepared from either undisturbed bees or bees that have been previously exposed to the antibiotic oxytetracycline, commonly used to treat fire blight in crops. This way, the naive bees can receive an altered microbiome without directly being subjected to the antibiotic. Finally, bees will be challenged with a viral pathogen to study the defensive mechanisms of the microbiome.

Unravelling the effects of direct and indirect antibiotic-induced gut dysbiosis can help gain a better insight into the mechanisms underlying the negative effects of antibiotic exposure on bee survival and pathogen infection prevalence.