Exposure route and life stage influence pesticide toxicity for an important biological control agent (Hippodamia convergens)

The convergent ladybird beetle (Hippodamia convergens) is an important natural enemy in agricultural ecosystems. The effects of pesticide exposure on adult H. convergens were recorded for five pesticide groups commonly used in orchards within the Western United States: diamides (Altacor, Cyazypyr), fungal metabolites (Delegate), insect growth regulators (Rimon), pyrethroid (Warrior II), and fungicides (Kumulus, Kocide-Manzate). For the majority of pesticides tested, residual exposure is not lethal to adults. However, oral exposure to adults resulted in 30% mortality for Cyazypyr, while Rimon, Kumulus, and Kocide-Manzate had no lethality. Furthermore, it appears that life stage may affect toxicity. First instar larvae exposed to Cyazypyr experienced mortality rates of 50%, whereas, again, Rimon, Kumulus, and Kocide-Manzate were not lethal. Although, some pesticides showed no lethality regardless of exposure route and life stage, further evaluation is necessary to determine sublethal effects on fecundity and development time.