Microbial symbionts in fungus culturing ambrosia beetles

Agriculture by insects evolved once in ants, once in termites and at least ten times in weevils. All of them farm specialized fungi for food, which they do so in cooperative societies, in which planting, protecting, cultivating and harvesting of the crops are shared by several individuals.  Whereas sociality evolved before fungiculture in ants and termites, both traits co-evolved in the so called ambrosia beetles (Scolytinae and Platypodinae). Recently, we could show that larval and adult stages of several ambrosia beetle species not only trigger the formation of nutritional fruiting structures in their fungal crops, but are apparently also able to suppress the growth of fungal weeds. Both may involve “microbial helpers” of the beetles.

In our research we aim to (1) identify the community of microbes (i.e. bacteria, yeasts and filamentous fungi) associated with different ambrosia beetle species (varying in their sociality and mode of fungiculture) using culture-dependent and independent methods (next-generation-sequencing), (2) unravel effects of particular microbes on the beetles’ fungal crops by combining controlled bioassays (based on established protocols to breed the beetles in the laboratory) with molecular and visualizing techniques (i.e. next-generation sequencing, SEM, FISH). Finally, provided appealing interactions, we want to isolate and chemically identify growth enhancing/antibiotic substances either from beetle extracts or particular symbionts.  Altogether, understanding the mechanisms how insect farmers are maintaining their cultures e.g. against crop diseases over millions of years may give new ideas for humans in how to sustain monocultures.