Parasitoids of the leafminer, Phyllonorycter nr. elmaella (Lepidoptera: Gracillariidae), on apple in California: Abundance, impact on leafminer, and insecticide-induced mortality

Abstract

Abstract Parasitoids of an undescribed species of apple leafminer, Phyllonorycter nr. elmaella , were studied to determine their relative and seasonal abundance. Thirty-six percent of all parasitoids were Sympiesis marylandensis Girault, 48% were Pnigalio flavipes (Ashmead), 7% were Zagrammosoma mirum Girault, >1% were Pholetesor ornigis (Weed), and the remaining 10% were other eulophids. Percentage parasitism varied greatly between leafminer generations and between locations during the apple growing season. Cannibalism caused 45% of the mortality during the first generation and 10 and 14% during the third and fourth leafminer generations, respectively. Pesticide residues targeted for control of codling moth, Cydia pomonella (L.), caused 90–100% mortality of the two most abundant parasitoids 24 h after application. S. marylandensis was more susceptible than P. flavipes to azinphosmethyl residues.