This thesis focuses on two invasive species, spotted wing drosophila (Drosophila suzukii) and the brown marmorated stink bug (Halyomorpha halys). The first chapter investigates the potential of native parasitoids to increase their developmental success on D. suzukii. Two native parasitoids were subjected to 10 generations of selection on D. suzukii and fitness metrics were measured in generations 0, 3, and 10. Both parasitoid species responded rapidly to selection, reaching peak developmental success on the novel host within three generations, which they then maintained for seven additional generations. There was no increase in preference towards the novel host or changes in development time or body size associated with adaptation. The sex ratio became less female biased for both parasitoids after three generations of selection but rebounded in one species by generation 10. These results indicate that artificial selection can increase the performance of native parasitoids within a few generations and may be used to improve biocontrol when co-adapted natural enemies of invasive species are not available. The second chapter investigates how the fitness of the adventive parasitoid of H. halys, Trissolcus japonicus, may change in response to intermittent or continuous exposure to a non-target native stink bug species. Acceptance of the native stink bug species did not increase with either intermittent or continuous exposure. However, reproduction on the native host resulted in a significant fitness cost for T. japonicus and compromised the fitness of the parasitoid on its original host species. These results suggest that non-target effects of T. japonicus may remain insignificant in nature given the fitness cost of attacking native species.
Read
