PLANT-INSECT-SYMBIONT INTERACTIONS: MECHANISMS OF RESISTANCE AGAINST AN INVASIVE, XYLOPHAGOUS BEETLE

The Asian longhorned beetle (ALB) was introduced into the U.S. from China and was recently listed among the 100 most threatening plant or animal invasive species worldwide. This beetle has killed thousands of high-value shade and timber tree species in the U.S., with a preference for maple trees. ALB has established in several states and attacks at least 25 different types of hardwood trees in both urban and forest habitats. It has the potential to eliminate 35% of the urban trees in the U.S., valued at $669 billion and its impact on poplar plantations used for biofuels could be especially devastating. Poplar plantations comprise the largest portion of intensively managed hardwood forest in North America. ALB develops deep in healthy trees using a community of microbes in its gut to help them break down their food source and obtain essential nutrients. ALB co-evolved in China with Chinese white poplar, which is resistant, while other poplar species native in the U.S. grown in poplar plantations are highly susceptible. Our goal is to understand how plant defenses in Chinese poplar impact the community of gut microbes and how this, in turn, impacts the fitness of the insect. Our approach will be to study how defensive chemicals in the resistant tree affect the ability of the insect to obtain nutrients and break down toxic chemicals from the tree. The outcome of this project will be identify plant defensive compounds that can be used to develop resistant tree cultivars, starting with poplars since the technology is already available. Ultimately these resistance traits can be moved into maples and other preferred ALB hosts as the tools become available. Development of trees resistant to ALB is considered the best strategy for managing this destructive, invasive beetle.