A laboratory assessment of the toxic attributes of six ‘reduced risk insecticides’ on Galendromus occidentalis (Acari: Phytoseiidae)

► Impacts of new pesticides on the predator Galendromus occidentalis were evaluated. ► Flubendiamide is harmless to G. occidentalis under worst-case laboratory exposure. ► Spinetoram and spirotetramat are toxic to all growth stages of G. occidentalis. ► Novaluron, clothianidin and chlorantraniliprole show some adverse effects. The modified excised leaf disc method was used to measure the effects of six insecticides on eggs, larvae, adults, and female fecundity of Galendromus occidentalis (Nesbitt) in a ‘worst case laboratory exposure’. This study identified insecticides that would be recommended for tier II field evaluations for an integrated pest management program. Commercially formulated insecticides were applied with a thin-layer chromatography sprayer adjusted to 10.34kPa (1.5psi), at the recommended label concentrations in Canada. LC50 values were estimated from aliquots above and below that concentration. Spinetoram and spirotetramat were toxic at label concentrations. The label concentration for spinetoram was 34.3-fold the LC50 estimate (0.006gL−1) and for spirotetramat the label concentration was 7.7-fold the LC50 estimate (0.03gL−1). Clothianidin was considerably less toxic and the label concentration was 0.15-fold the LC50 estimate (2.29gL−1). Estimates of LC50 for novaluron and chlorantraniliprole could not be established. Both materials showed slight toxicity to at least one growth stage of the predator. Novaluron, clothianidin and chlorantraniliprole should be evaluated in the field for compatibility in IPM programs. Flubendiamide was harmless to all growth stages and it is recommended for inclusion in IPM programs without additional tier II field evaluations. Field evaluations with spinetoram and spirotetramat should be pursued only if alternatives are unavailable.