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Susceptibility of adult Trichogramma nubilale (Hymenoptera: Trichogrammatidae) to selected insecticides with different modes of action

Wang, Yanhua, Yu, Ruixian, Zhao, Xueping, Chen, Liping, Wu, Changxing, Cang, Tao, Wang, Qiang
Crop protection 2012 v.34 pp. 76-82
Ostrinia furnacalis, Trichogramma nubilale, acute toxicity, avermectins, biological control, carbamates, corn, insect growth regulators, integrated pest management, lethal concentration 50, mechanism of action, neonicotinoid insecticides, parasitoids, pyrethrins, risk, risk analysis
The parasitic wasp Trichogramma nubilale (Hymenoptera: Trichogrammatidae) is one of the most suitable parasitoids for controlling Asian corn borer, Ostrinia furnacalis (Lepidoptera: Crambidae). Although extensive toxicological tests have been carried out to elucidate the toxicities of insecticides to trichogrammatids, the acute toxicity risks of commonly used insecticides to T. nubilale are not well known. Among the 7 classes of tested chemicals, organophosphates and carbamates had the highest intrinsic toxicity to the parasitoid with LC₅₀ values ranging from 0.081 (0.062–0.12) to 2.10 (1.23–3.47) and from 0.12 (0.11–0.14) to 0.95 (0.87–1.05) mg a.i. per liter, respectively. The phenylpyrazoles (with the exception of butene-fipronil), avermectins, neonicotinoids and pyrethroids induced intermediate toxicity responses with LC₅₀ values ranging from 0.29 to 4.67, 2.36 to 11.27, 1.86 to 311.9, and 10.98–150.3 mg a.i. per liter, respectively. In contrast, insect growth regulators (IGRs) exhibited the least toxicity to the parasitoid with LC₅₀ values ranging from 3452 (3114–3877) to 10,168 (8848–12,027) mg a.i. per liter. A risk quotient analysis indicated that neonicotinoids, avermectins, pyrethroids, IGRs and phenylpyrazoles (with the exception of butene-fipronil) were safe, but organophosphates and carbamates were slightly to moderately toxic or highly toxic to T. nubilale. This study provided informative data for implementing both biological and chemical control strategies in integrated pest management (IPM) of corn lepidopterans.