Ambrosia Beetles and Fungi
Ambrosia beetles are a group of unrelated scolytine weevil clades defined by a shared ecological strategy: fungus farming. Most bark and ambrosia beetles (the two weevil subfamilies Scolytinae and Platypodinae) are somehow associated with fungi. The relationship varies from association with phytopathogens, through enrichment of herbivorous diet with fungal mycelia, to strict mycetophagy. Ambrosia beetles are the vaguely defined end of this spectrum, the beetles which, instead of eating tree tissues as their ancestors, carry around symbiotic fungi, inoculate them into the trees they colonize, and are dependent on fungi as their main source of food. [20] |
The beetles are not able to survive and develop on a fungus-free diet composed only of plant tissue. A direct consequence of condition is that larvae do not form their own feeding tunnels. Deploying mycelia of symbiotic fungi as means of extracting nutrients from trees freed ambrosia beetles from facing the defense mechanisms of trees. As a result, host tree range of some ambrosia beetles seem nearly unlimited. [21] |
There are about 3,200 described species of ambrosia beetles. That's more than in any of the other fungus-growing insect groups. Moreover, some ambrosia beetles are still diversifying unusually fast. The beetles are also a dominant component of the beetle fauna of tropical forests. Even if you include beetles chewing leaves or boring into roots, ambrosia beetles are still the most speciose group of beetles. [22] |