Funded Research Projects: FOREST ECOLOGY

Elucidating traits and factors determining the risk of introduced herbivorous insects on North American native plants

Research Sponsored By: US Forest Service
Principal Investigator: Patrick Tobin
Project Description
High-impact insect invasions cause widespread ecological and economic damage. Introduced insects that feed on host plants of a single genus (hereafter, genus specialists) are particularly problematic as they can potentially eliminate an entire genus of native host plant species on a landscape scale. However, most introduced genus specialists do not become high-impact pests. We posit that the ecological and evolutionary interplay between the level of specialization of an introduced genus-specialist insect to its new hosts and lack of defenses by evolutionarily naïve host plants drive the impact of the invasion. To inform risk assessment and invasive species management, the objective of this project is to develop a framework from which we can predict – prior to their establishment – those insects that will threaten the existence of their novel host plants. Under this proposal, we propose a continental scale study of high-impact insect invasions caused by genus specialists. We will examine the contribution of five types of drivers toward these impacts: (1) the insects’ and host plants’ evolutionary history, (2) the hosts’ defenses or lack thereof (defense-free space), (3) presence of natural enemies or lack thereof (enemy release), (4) invader traits, and (5) geographic and temporal considerations. We will synthesize data on traits and factors representing these drivers to build and parameterize a predictive model of the potential impact of introduced insects as a function of the traits and factors. The model will allow us to examine the contribution of each of the hypothesized drivers toward invasion impact and provide insight on the defense-free space hypothesis versus the alternative enemy release hypothesis. We will then apply the model to insects with a high likelihood of introduction to the U.S. to rank their probability of becoming significant threats if introduced.