|WANG, HUAI YIN|
|YA SU, JIAN|
|SHEN, JIN LIANG|
|GAO, CONG FEN|
|Zhu, Yu Cheng|
Submitted to: Crop Protection Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2007
Publication Date: 4/15/2008
Citation: Wang, H., Yang, Y., Ya Su, J., Shen, J., Gao, C., Zhu, Y. 2008. Assessment of Impact of Insecticides on Anagrus nilaparvatae (Pang et Wang) (Hymenoptera: Mymanidae), an Egg Parasitoid of the Rice Planthopper, Nilaparvata lugens (Hemiptera: Delphacidae). Crop Protection Journal.27:514-522
Interpretive Summary: Currently, many low toxicity organophosphates, pyrethroids, and other novel insecticides are sought and considered as potential alternatives to replace highly toxic organophosphate insecticides for rice insect control. In addition to evaluating their toxicological effect against target insects, these insecticides must be subjected to the assessment of impact on natural enemies. In this study, fourteen insecticides representing seven insecticide classes, including organophosphates, carbamates, pyrethroids, insect growth regulators (IGRs), new nicotine, diphenylpyrazole, antibiotics, etc., were selected to investigate sublethal and lethal effects on adult parasitoid of the brown rice planthopper. The parasitoids were exposed to the insecticides through three potential routes, contact, oral, and residual, to examine their acute and chronic toxicities for determination of the compatibility of biological agent with chemical control in the integrated management program of the rice planthopper.
Technical Abstract: The parasitoid Anagrus Nilaparvatae (Pang et Wang) (Hymenoptera: Mymanidae) is a major natural enemy of the rice planthopper Nilaparvata lugens (Hemiptera: Delphacidae). It plays an important role in the IPM of the rice planthopper. Contact and oral toxicity and residual effect of fourteen pesticides representing seven insecticide classes, including organophosphates, carbamates, pyrethroids, insect growth regulators (IGR), neonicotine, phenylpyrazole, and antibiotics on mature stage of the parasitoid were investigated under laboratory conditions. The acute and chronic effects of pesticides on A. nilaparvatae were determined. Contact toxicity of the 14 insecticides was ranked as follows: chlorpyrifos > imidacloprid > fipronil and methamidophos > thiamethoxam, isoprocarb, and triazophos > abamectin, silafluofen, and dichlorvos > buprofezin, JS118, hexaflumuron, and chlorfluazuron. Results of oral toxicity tests of 14 pesticides showed that dichlorvos was the most toxic pesticide, which generated 100% mortality only 2 hours after treatment. Isoprocarb, imidacloprid, and thiamethoxam were the second most toxic insecticides and killed all wasps in four-hour period. Imidacloprid was the most persistent insecticide, and it retained residual toxicity (79.3% mortality) on rice leaves up to 7 days after treatment. Thiamethoxam, triazophos, and fipronil also had long residual toxicity to the wasps with 7-day mortalities as 66.8%, 54.6%, and 50.0%, respectively. IGRs showed very low contact and residual toxicities, but exhibited certain chronic effect of oral toxicity on longevity, oviposition, and offspring emergence.