The gut microbiota - brain axis of insects.

Research on the connections between gut microbes and the neurophysiology and behavior of their animal hosts has grown exponentially in just a few years. Most studies have focused on mammalian models as their relevance to human health is widely established. However, evidence is accumulating that insect behavior may be governed by molecular mechanisms that are partly homologous to those of mammals, and therefore relevant for the understanding of their behavioral dysfunctions. Social insects in particular may provide experimentally amenable models to disentangle the contributions of individual bacterial symbionts to the gut microbiota - brain axis. In this review, we summarize findings from recent research on the neurological and behavioral effects of the gut microbiota of insects and propose an integrated approach to unravel the extended behavioral phenotypes of gut microbes in the honey bee.