Sublethal effects of Thymus vulgaris essential oil on life-table parameters of two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae)

Abstract

Sublethal effects of Thymus vulgaris were investigated on life-table parameters of Tetranychus urticae Koch (Acari: Tetranychidae) in the laboratory conditions at 25 ± 1 °C, 70 ± 10% RH and a 14:10 h (L:D) photoperiod. Bioassay was conducted to assess the effect of different concentrations of T. vulgaris essential oil on two-spotted spider mite. LC50 and LC20 of T. vulgaris on T. urticae were calculated as 18.86 and 6.24 μl/litre air for 24 h after treatment. In the sublethal effects, after 24 h exposure to LC50 concentration, mortality, fecundity and longevity of the females that survived from treatment were determined. Results showed that T. vulgaris caused significant reductions in fecundity and longevity of adults. Life-table assay indicated that the intrinsic rate of increase (r m), net reproductive rate (R 0), finite rate of increase (λ), mean generation time (T), significantly reduced in treated females compared to control. These results suggest that T. vulgaris could be incorporated in integrated pest management programmes of T. urticae.