Effects of rising temperatures on ectosymbiotic communities associated with bark and ambrosia beetles

The ectosymbiotic community associated with bark and ambrosia beetles is diverse and speciose and adapted for life within tree tissues. This community—composed of fungi, bacteria, viruses, nematodes, and mites—interacts with beetle hosts in a variety of ways. Interactions are often not simple or clearly understood, and are rather context-dependent, shifting with changing environments. Ectosymbionts also interact with the tree and with natural enemies and competitors of beetle hosts within trees. In this chapter, we describe the effects of changing climate, especially elevated temperatures, on the composition and interactions of the ectosymbiotic community associated with bark and ambrosia beetles. We address (1) how changes in climate can differentially affect growth and reproduction of ectosymbiotic species, (2) how climate can drive changes in tree condition, increasing or decreasing secondary defenses, phloem nutrients, and moisture and affecting ectosymbionts associated with beetles, and (3) how climate change affects interactions among ectosymbionts, beetles, and trees.