Journal of Zhejiang Agricultural Sciences ›› 2025, Vol. 66 ›› Issue (5): 1232-1236.DOI: 10.16178/j.issn.0528-9017.20240043

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Control efficacy and resistance of spinetoram applied at different periods against Chilo suppressalis in rice

CAO Mi'na1(), WU Cong2,*()   

  1. 1. Dongyang Agricultural Technology Extension Center, Dongyang 322100, Zhejiang
    2. Lanxi Agricultural Technology Extension Center, Lanxi 321100, Zhejiang
  • Received:2024-01-12 Online:2025-05-11 Published:2025-05-20

Abstract:

To investigate the control efficacy of insecticides sprayed at different infestation periods of Chilo suppressalis and to assess the resistance of Chilo suppressalis larvae to spinetoram in various towns and subdistricts, rice seedling dipping method and field trials were conducted. The results showed that 25% spinetoram water-dispersible granules (WG) demonstrated better seedling protection and insecticidal effects when applied at a deadheart rate ≤10%, especially when the deadheart rate was 0%-5%. At 20 days after application, the insecticidal and seedling protection effects reached 64.40% and 68.62%, respectively. However, when applied at a deadheart rate >15%, the insecticidal and seedling protection effects of 25% spinetoram WG at 20 days after application were relatively poor, at 17.78% and 21.74%, respectively. Significant differences in resistance levels to spinetoram were observed among Chilo suppressalis larvae from different towns and subdistricts. Larvae from Xiangxi Town, Shuiting Town, Yongchang Subdistrict, Shanghua Subdistrict, and Youbu Town had developed moderate resistance to spinetoram, with Youbu Town exhibiting the highest resistance (LC90 = 633.34 mg·L-1). Overall, spinetoram exhibited high biological activity against Chilo suppressalis larvae in most towns and subdistricts. Field application of 25% spinetoram WG is recommended when the deadheart rate is ≤10%, and it can be mixed or alternated with other insecticides for enhanced control.

Key words: Chilo suppressalis, spinetoram, different application periods, resistance, control efficacy

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