Insecticide toxic effects on Trichogramma ostriniae (Hymenoptera: Trichogrammatidae).

BACKGROUND

The parasitoid Trichogramma ostriniae (Pang and Chen) is a major natural enemy of many lepidopterans, but only a few studies have been conducted on the compatibility of biological and chemical controls. In this study, the selectivity of 30 insecticides to T. ostriniae adults was evaluated.

RESULTS

Among the seven classes of chemicals tested, organophosphates and carbamates had the highest intrinsic toxicity to the wasp, with LC(50) values ranging from 0.032 (0.029-0.038) to 2.38 (1.91-3.15) mg AI L(-1). They are followed by phenylpyrazoles, avermectins, neonicotinoids and pyrethroids, which induce variable toxicity responses, with LC(50) values ranging from 0.14 (0.11-0.21) to 56.67 (48.94-67.24) mg AI L(-1), from 2.57 (1.85-4.28) to 4.48 (3.34-6.83) mg AI L(-1), from 2.48 (1.80-4.03) to 503.6 (457.6-557.5) mg AI L(-1) and from 5.44 (3.95-8.84) to 104.2 (92.48-119.7) mg AI L(-1) respectively. The insect growth regulators (IGRs) exhibited least toxicity to the parasitoid.

CONCLUSION

Risk quotient analysis classifies neonicotinoids, avermectins, pyrethroids, IGRs and phenylpyrazoles (with the exception of butane-fipronil and fipronil) as safe agents to the parasitoid, but categorises organophosphates and carbamates as slightly to moderately toxic or dangerous to T. ostriniae.