Impact of hexythiazox on life table parameters of the Amblyseius swirskii (Acari: Phytoseiidae) and its prey Tetranychus urticae

The two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important and destructive herbivorous mites in farm and greenhouse that has developed high levels of resistance to many acaricides. In this study, we investigated the effect of sublethal concentrations of hexythiazox at LC۱۰, LC۲۰, and LC۳۰ on the development and reproduction parameters of Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) and its prey T. urticae. The crude data were analyzed based on age-stage, two-sex life table analysis. Hexythiazox (at LC۲۰ and LC۳۰ levels) reduced the oviposition period (۹.۶۸, ۸.۰۶ days), total lifespan (۲۲.۳۷, ۲۰.۸۸ days), and total fecundity (۵۰.۹۷, ۴۶.۲۱ eggs/female) compared to the control but did not affect those parameters of A. swirskii. The intrinsic rate of increase (r) and finite rate of increase (λ) were not significantly different at tested concentrations, but the net reproductive rate (R۰), gross reproductive rate (GRR), and mean generation time (T) reduced significantly. Our study demonstrated lower toxicity of hexythiazox on A. swirskii compared to its prey. It could be concluded that the use of selective acaricides at lower concentrations may be helpful in integrated pest management programs.

Keywords:

Two-spotted spider mite , LC۵۰ , life table , biological parameters , Phytoseiidae