Evolutionary feedbacks between insect sociality and microbial management.

Fitness-determining interactions with microbes-in particular fungi-have often been considered a by-product of social evolution in insects. Here, we take the view that both beneficial and harmful microbial consortia are major drivers of social behaviours in many insect systems-ranging from aggregation to eusociality. We propose evolutionary feedbacks between the insect sociality and microbial communities that strengthen mutualistic interactions with beneficial (dietary or defensive) microbes and simultaneously increase the capacity to defend against pathogens (i.e. social immunity). We identified variation in habitat stability-as determined by breeding site predictability and ephemerality-as a main ecological factor that constrains these feedbacks. To test this hypothesis we suggest following the evolution of insect social traits upon experimental manipulation of habitat stability and microbial consortia.