The effects of insecticides used for California citrus pest management were tested on various stages of vedalia beetles, Rodolia cardinalis (Mulsant), to determine their relative toxicity to this natural enemy that is essential for cottony cushion scale control, Icerya purchasi (Williston) in the San Joaquin Valley. When the vedalia stages were fed insecticide-treated cottony cushion scale reared on Pittosporum plants, toxicity was higher compared to contact toxicity alone. The pyrethroids and neonicotinoids were highly toxic to adults and larvae. The juvenile hormone mimic pyriproxifen was highly toxic to eggs and larvae. The chitin synthesis inhibitor buprofezin was highly toxic to larvae. The other classes of insecticides, the organophosphate methidathion, spinosad, abamectin, and veratran were relatively nontoxic to vedalia stages tested. In the context of citrus IPM, insect growth regulators, neonicotinoid insecticides and pyrethroid insecticides have a significant impact on vedalia beetles. Depending on rate, number of applications, coverage, and timing of application, disruption of vedalia can be avoided. However, the situation is made difficult when newly introduced, severely damaging pests such as glassy-winged sharpshooter require treatments during periods of vedalia beetle activity or multiple applications.
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