The leek moth is a European pest of Allium spp. established near Ottawa, Ontario, Canada in the early 1990's. Its spread throughout eastern Canada and into the northeastern United States represents the potential for significant economic losses to Allium growers. Using a life-table approach, we aimed to determine if resource supplementation would influence the species composition, relative abundance and host-killing ability of indigenous parasitic wasps in the leek moth system and the classical biological control agent, Diadromus pulchellus. In greenhouse cages, adding buckwheat to a sugar-deprived system increased the longevity, and parasitism levels of D. pulchellus; however, a similar effect was measured on the facultative hyperparasitoid, Conura albifrons. In the field, the parasitoid species composition was the same in both buckwheat-supplemented and standard leek plots; however, the parasitoid community differed between the standard and resource-enriched plots. These studies provide insight into how conservation biological control may affect classical biological control.