When the beetle begins farming
Agriculture is usually regarded as a unique human feature, and one that is contingent on social structures. But there are also insects that are dedicated farmers who rely on cultivated fungi - a great evolutionary success under warm and moist conditions.
Kara Rogers writes about this phenomenon in a recent blog post on Encyclopaedia Britannica Science Up Front series. Fungus farming is only known from some termites and ants, and in several groups of wood boring beetles. Each and one of these groups have developed social family systems which are beneficial to localised farming of fungi. In bark and ambrosia beetles, fungus farming has evolved at least ten times independently, with peculiar adaptations to a symbiotic life style together with their associated strains of fungi. In a recent paper by Jordal and Cognato, the origin of fungus farming is estimated by phylogenetic analyses of a large number of gene sequences. Results demonstrate how most origins happened under periods of global warming characterised by extensive rain forests where these beetles are most successful.