Sublethal effects of spirodiclofen on the demographic parameters of Tetranychus urticae Koch (Acari: Tetranychidae)

Abstract

The two-spotted spider mite, Tetranychus urticae Koch is one of the most common pests of agricultural crops. The use of sublethal doses can reduce the need of pesticides and prevent pests’ resistance, which is an important step in integrated pest management and safely controlling this pest. The sublethal effects (LC5, LC15 and LC35) of spirodiclofen on demographic parameters of T. urticae based on the age-stage, two-sex life table theory were investigated under laboratory conditions [25 ± 2 °C, 60 ± 5% RH and 16:8 (L:D) h]. The longevity, total life span, oviposition period and total fecundity reduced after exposure to LC15 and LC35. Oviposition period ranged from 5.64 to 10.92 days. The gross reproduction rate (GRR), net reproductive rate (R0) and the finite rate of increase (λ) of the mites treated with LC15 and LC35 were inferior to the results when treated with LC5, and control. The values of intrinsic rate of increase (r) was 0.2209 day−1 in the control and this was reduced to 0.1714 day−1 in LC35. Based on these results, considering the negative impact of spirodiclofen on the population growth of T. urticae, this acaricide can be helpful to achieve an efficient control for T. urticae in frame of integrated pest management.