Invasion ecology of non-native forest insects

点击翻译按钮获取中文摘要

My research investigates the ecological basis of invasiveness to understand why some non-native species grow and expand to high and damaging densities, while others persist at low densities. Successful interchange of insect invaders between Europe and North America occurs due to similarities in their forest and faunal composition. However, North America receives more successful invaders than the reverse. Using three forest insect systems, I will test whether the extent to which non-native species become invasive can be explained by their life history traits and interactions with the novel community, including host trees, congeners, niche-sharers, and natural enemies. 1) To evaluate reciprocal invasion potential, we will compare community interactions of spruce bark beetles, the European Ips typographus and North American Dendroctonus rufipennis, in their respective native and invaded ranges. We will test whether: i) reproductive success is higher on nave host species, ii) invasion success in the new range is favoured by niche-sharing congeners and mitigated by their natural enemies, and iii) there are barriers to gene flow among populations that result in pheromone races that differ in invasion potential. 2) To evaluate whether mating interactions with natives can slow down an invasion, we will test whether interspecific matings occur between the non-native brown spruce longhorn beetle, Tetropium fuscum, and its native congener, T. cinnamopterum. We will construct a library of molecular markers unique to each species that will allow us to screen individual Tetropium spp. specimens for hybrid genotypes in the field. Sequences of T. fuscum from different European populations will be compared to Canadian populations to determine whether divergence and/or introgression have occurred since the invasion. 3) To determine whether trophic interactions influence invasion potential in Europe and Canada, we will test whether interactions between i) insect-host tree, ii) insect-fungus and iii) fungus-host tree affect colonization potential of non-native ambrosia beetles, Xylosandrus germanus and Xylosandrus crassiusculus that differ in their invasiveness. Results from these studies will help build a community ecology framework to evaluate invasiveness of potential non-native species that have been intercepted and may establish in Canada.