Sublethal effects of reduced risk pesticides on the biological control agent, Hippodamia convergens

Hippodamia convergens (the convergent ladybird beetle) is an important biological control agent, particularly within orchard agroecosystems in Western North America.  Recently, reduced risk pesticides have been increasingly used in these systems to control pests, but their effect on natural enemy populations is unclear.  To determine how reduced risk pesticides affect life history traits of H. convergens, first instar larvae were exposed to a given pesticide through three different exposure routes simultaneously: oral, residual, and direct.  Insect development was then monitored until the adult life stage.  For Altacor, Cyazypyr, Kumulus, and Rimon, survivorship was less than 50% after 48 hrs, and less than 7% of insects developed into adults.  For Delegate, survivorship was 84% after 48 hrs, and 53% of insects reached the adult life stage.  Kocide-Manzate was the only pesticide with adult survivorship rates comparable to controls (84%).  Overall, these results may inform both researchers and growers about conservation of natural enemies and improve pest management decisions.