Sublethal effects of fenazaquin on biological performance of the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae): application of age-stage, two-sex life tables

Abstract

Estimating sublethal effect of acaricides is a reliable approach in predicting of pesticide impacts. Our study evaluated the sublethal effects of fenazaquin (Pride®) on life table parameters of the subsequent generation of the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions at 25–27 oC, 60±3% RH and a photoperiod of 16:8 (L:D) hours. Adult individuals of T. urticae were exposed to different concentrations of fenazaquin and LC10, LC20 and LC30 were determined based on concentration-response bioassay. The total developmental period of both sexes increased with increasing concentration from LC10 to LC30. Fenazaquin treatments gradually reduced the longevity and total life span in both sexes and this reduction increased with increasing concentration. All reproductive periods declined in a concentration-dependent manner. Or data indicated a significant reduction in the intrinsic rate of increase (rm), the net reproductive rate (R0) and the finite rate of increase (λ) of the mites treated with LC20 and LC30 concentrations. Moreover, the shortest mean generation time (T) belonged to the LC30 treatment, which caused the longest doubling time (DT). Understanding of sublethal effects of fenazaquin can be useful in designing management programs for T. urticae.