BIOLOGICAL CONTROLÐPARASITES AND PREDATORS Endoparasitoid Assemblage of the Pea Leafminer, Liriomyza huidobrensis (Diptera: Agromyzidae), in Southern Ontario

The pea leafminer, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), is an important pest of leafy greens in the Holland Marsh, Bradford, Ontario, and was Þrst discovered in this area in 1998. A 2-yr study was undertaken to document the parasitoid complex of this recent addition to leafminer guild in Ontario and examine endoparasitoids reared from pea leafminer pupae collected from eight host plants: celery (Apium graveolens L.), spinach (Spinacia oleracea L.), lettuce (Lactuca sativa L.), mustard greens (Brassica juncea L.), pea (Pisum sativum L.), potato (Solanum tuberosum L.), and gai lan (Brassica alboglabra L.). Members of three families of Hymenopteran parasitoids were identiÞed: Chrysocharis oscinidis Ashmead (Eulophidae), Halticoptera circulus (Walker) (Pteromalidae), and three species in the Braconidae, including two unidentiÞed Dacnusa spp. and one unidentiÞedOpius sp. Mortality and parasitism rates of pea leafminer pupaewere higher in 2002 than 2003 and varied according to host plant. Parasitism rates ranged from 4 to 27% in 2002 and 4% to 13% in 2003. The parasitoid complex differed among host plants, and there were differences in the range of host plants on which parasitoids were found to parasitize pea leafminers.