Ambrosia beetles grow gardens of fungi that produce nutritious spores to feed the beetles and their larvae. In exchange for these spores, the beetle carries the fungus from tree to tree, penetrating the protective bark and depositing the fungus in fresh dead wood. But how do the beetles pick a nutritious fungus from the myriad others that live in rotting wood? We used symbiont swapping experiments and co-phylogenetic analysis to show that each beetle’s mycangium – a specialized pouch for transporting live fungus – is partial to certain species of closely related fungi. As a result, we can predict the likelihood of two beetle species exchanging their symbionts. This is important because some non-native beetles farm pathogenic, tree-killing fungi that may be passed to native beetles with dire consequences. Our work can help managers focus on the biggest risks. Read the full story here: https://royalsocietypublishing.org/doi/full/10.1098/rspb.2018.2127