Lethal and sublethal effects of fluralaner on the two‐spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae).

BACKGROUND: Two‐spotted spider mite (TSSM), Tetranychus urticae Koch is a serious agricultural pest and has developed high levels of resistance to many acaricides. Hence, screening new acaricides is important in the control of TSSM. Fluralaner, a novel isoxazoline, has high activity against agricultural and ectoparasitic pests; however, little information is available about its effects on agricultural mites. Lethal and sublethal effects of fluralaner towards TSSM eggs and female adults were therefore evaluated in this study. RESULTS: Fluralaner exhibited higher activity towards TSSM female adults (LC50, 0.49 mg L−1) compared with commercial acaricides including fenpyroximate, pyridaben and hexythiazox, and also excellent activity towards eggs (LC50, 0.36 mg L−1). The results of a sublethal effect study showed a significant reduction in the duration and fecundity of female adults with increases in the tested concentrations. The net reproductive rate (R0) decreased to 67.34 ± 3.96 and 50.29 ± 3.40 offspring per individual in LC10 and LC30 treatments compared with control (108.31 ± 7.61 offspring per individual). The intrinsic rate of increase (r) and finite rate of increase (λ) in the controls (0.30 and 1.36 d−1) were significantly higher than in the LC30 treatment (0.25 and 1.29 d−1); whereas, they were almost identical to values for the LC10 treatment. No change in mean generation time (T) was observed at sublethal concentrations treatments. CONCLUSION: Our results demonstrated that fluralaner has high acaricidal activity and could be considered a potential acaricide for TSSM management. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]