Journal of Economic Entomology (2022) 115, 446-454

Lian-Cheng Xie, Lin-Hong Jin, Yan-Hui Lu, Hong-Xing Xu, Lian-Sheng Zang, Jun-Ce Tian and Zhong-Xian Lu (2022)
Resistance of Lepidopteran egg parasitoids, Trichogramma japonicum and Trichogramma chilonis, to insecticides used for control of rice planthoppers
Journal of Economic Entomology 115 (2), 446-454
Abstract: Trichogramma wasps are commonly used as biocontrol agents to manage lepidopteran rice pests in rice fields. However, lepidopteran pests synergistically occur with rice planthoppers which are not targeted by Trichogramma. The use of Trichogramma parasitoids in field-based pest control efforts is greatly affected by the application of insecticides targeting planthoppers. As such, insecticide-resistant strains of Trichogramma are urgently needed for the incorporation of these beneficial natural enemies into integrated pest management programs in rice agroecosystems. In the present study, Trichogramma japonicum Ahmead (Hymenoptera: Trichogrammitidae) and Trichogramma chilonis Ishii (Hymenoptera: Trichogrammitidae) were treated with sublethal doses of four insecticides which target rice planthoppers, to generate tolerant strains in the laboratory. The resistance rate of T. japonicum to imidacloprid was the highest (17.8-folds) after 10 successive treatments and experienced 2.5, 4.72, and 7.41-fold increases in tolerance to thiamethoxam, buprofezin, and nitenpyram, respectively. Tolerance of T. chilonis to imidacloprid, thiamethoxam, buprofezin, and nitenpyram were 8.8, 6.9, 4.43, and 5.67-fold greater, respectively. The emergence and deformity (without spreading wings or short wings) rates of T. japonicum and T. chilonis gradually recovered with an increased exposure time of treatments. The fecundity of T. japonicum treated with thiamethoxam was significantly higher than that of the control and T. chilonis treated with thiamethoxam and nitenpyra. Our results demonstrate that screening for insecticide-tolerant/resistant Trichogramma strains was feasible, especially in the pairing of T. japonicum and imidacloprid, which could provide a valuable biological control tool that can be combined with traditional chemical control strategies for use in IPM of rice agroecosystems.
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Link to article at publishers website
Database assignments for author(s): Jun-Ce Tian, Lian-Sheng Zang

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance to pesticides

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Corcyra cephalonica	Rice (Oryza)	China (south)
Trichogramma chilonis (parasitoid)	Corcyra cephalonica	Rice (Oryza)	China (south)
Trichogramma japonicum (parasitoid)	Corcyra cephalonica	Rice (Oryza)	China (south)