The influence of plant sex on the performance of a detrimental herbivore and two biocontrol agents in the dioecious grey willow, Salix cinerea

Dioecious plants can be used as model systems for studying how variation in host plants affects plant-insect interactions. This thesis describes investigations into the impact of plant sex on plant-herbivore-predator interactions for the host plant Salix cinerea. Both herbivores and predators were found to prefer female plants, all other things being equal. As a result, top-down control had a more significant impact on the herbivore population on female plants than was the case for males. Despite this, Phratora beetles were more abundant on, and preferred, female plants. This may be due to bottom-up control, since female plants have longer leaves. Both herbivores and biocontrol agents were more abundant on female plants in the field. Because of predation by omnivores, survival rates for herbivore eggs on female plants were lower than those for male plants, and omnivore predation was the primary cause of death among herbivore eggs. These findings may provide novel opportunities for pest control in Salix short rotation coppices