Bark Beetles Control Pathogenic Fungi

Pathogens can drive the evolution of social behaviour in insects. This is shown by researchers from Bern and Würzburg for ambrosia beetles. Ants and honeybees share nests of hundreds or thousands of individuals in a very small space. Hence the risk is high that infectious diseases may spread rapidly. In order to reduce this risk, the animals have developed special social behaviours that are referred to as "social immune defence". This achievement is generally assumed to have evolved only in the eusocial insects including ants, bees and wasps. The finding that also more primitively social ambrosia beetles remove pathogens by cleaning each other indicates that social immunity may have evolved already much earlier.