Predicting the next high-impact insect invasion: Elucidating traits and factors determining the risk of introduced herbivorous insects on North American native plants

Non-native insect invasions increasingly cause widespread ecological and economic damage in natural and agricultural ecosystems. Non-native insects specialized for feeding on specific plant groups are particularly problematic as they can potentially eliminate an entire genus of native plant species across a wide area. For example, emerald ash borer has killed hundreds of millions of ash trees in North America since its accidental introduction from Asia, including more than 99% of all trees in forests near the epicenter of the invasion.  However, most introduced insects do not become high-impact pests. Our goal is to develop a framework that allows us to predict whether non-native herbivorous insects in natural ecosystems will cause widespread mortality of their host plants if they become established. On a continental scale, we are synthesizing data on traits and factors representing five types of drivers to build a predictive model of the potential impact of introduced insects. Those drivers are: (1) the insects’ and host plants’ evolutionary history, (2) the host plants’ 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 apply the model to insects with a high likelihood of introduction to the U.S. to rank their probability of becoming significant threats if established. The project outcomes will inform invasive species management and risk assessment. We will also be able examine the contribution of each of the hypothesized drivers toward invasion impact and contribute to testing the relative importance of the defense-free space and enemy release hypotheses in different systems.



Presentation:
Tobin, P.C., Marsico, T.D., Thomas, K.A., Herms, D.A., and Mech, A.M. “Looking for black and white in the grey: Variation in invasion success and management challenges in a global community.” International Congress of Entomology (ICE), September 2016, Orlando, Florida. Conference talk.

Publications:
Mech, AM, Thomas, KA, Marsico, TD, et al. Evolutionary history predicts high‐impact invasions by herbivorous insects. Ecol Evol. 2019; 00: 1– 15. https://doi.org/10.1002/ece3.5709

Durden, L.A., Schulz, A.N., Mech, A., and Thomas, K.A., 2020, A not so sudden impact—Historical relations between conifers and insects can help predict damage by nonnative insects: U.S. Geological Survey Fact Sheet 2020-3039, 4 p., https://doi.org/10.3133/fs20203039.