Abstract: The tea geometrid (Ectropis grisescens Warren) is the most destructive defoliator in tea gardens in China. In recent years, E. grisescens has developed medium to high level resistance against common pesticides. To address this challenge, six chemical pesticides and three biological pesticides were selected and comprehensively evaluated from four aspects: laboratory toxicity assays, field evaluation, safety assessment for natural enemies, and pesticide residue analysis in tea leaves. The results of laboratory toxicity assays indicate that matrine (LC₅₀: 3.54 mg·L^-1), spinetoram (LC₅₀: 4.12 mg·L^-1), and spinosad (LC₅₀: 9.68 mg·L^-1) exhibited potent contact toxicity against the 2^nd instar larvae. In the stomach toxicity tests, spinosad (LC₅₀: 0.01 mg·L^-1), matrin (LC₅₀: 0.10 mg·L^-1), spinetoram (LC₅₀: 0.31 mg·L^-1), methoxyfenozide (LC₅₀: 11.06 mg·L^-1), chlorfenapyr (LC₅₀: 38.80 mg·L^-1), and indoxacarb (LC₅₀: 49.87 mg·L^-1) exerted relatively optimal stomach toxic effects on the 2^nd instar larvae. The subsequent field efficacy trials reveal that spinetoram, chlorfenapyr, spinosad, and indoxacarb all showed remarkable control effects on E. grisescens larvae. Spinetoram achieved a control efficacy over 90% after 1 and 3 days of application, highlighting its rapid and remarkable properties. For the other three pesticides, their control efficacy surpassed 80% on the 7^th day, indicating ideal long-term effectiveness. The toxicity assessment of natural enemies indicates that the LC₅₀ values of spinetoram (LC₅₀: 5.39 mg·L^-1), and spinosad (LC₅₀: 39.75 mg·L^-1) for Arma chinensis were higher than those for the 2^nd instar larvae. This finding suggests that using spinetoram and spinosad to control E. grisescens in the field poses relatively low risks to natural enemies. Finally, the results of pesticide residue analysis shows that only indoxacarb remained at 0.30 mg·kg^-1 after 7 days of application, and no other pesticide treatments were detected, all of which met the maximum residue limit standards in China (GB 2763—2021). In conclusion, spinetoram and spinosad, characterized by their high efficiency and safety, were appropriate for rotational use to control the Ectropis grisescens.

Key words: Ectropis grisescens, laboratory efficacy, field efficacy, safety evaluation