Actinobacteria as mutualists: general healthcare for insects?

Mutualistic microorganisms are well known to play a key role in providing nutrients for successful growth and reproduction in many insects. Several recent studies indicate that they can be equally important for the protection of the host and its nutritional resources against pathogen attack. In particular, different actinobacteria have been found to defend ants, beetles and wasps against detrimental microorganisms by producing antibiotics. The extraordinary abilities of actinobacteria to exploit a wide variety of carbon and nitrogen sources and their extensive repertoire of secondary metabolites probably predispose this group to engage in protective symbioses. Defensive mutualisms with actinobacteria might constitute a general and widespread theme in the ecology and evolution of arthropods, and the study of the secondary metabolites involved promises to uncover novel drug candidates for human medicine.