Persian Journal of Acarology

Abstract The predatory mite Amblyseius swirskii is widely used as a biological control agent against spider mites, thrips, and whiteflies. This study examined the sublethal effects of two abamectin concentrations (LC10 and LC20 for A. swirskii) on life history traits and demographic parameters of the F₁ generation derived from treated parents under controlled laboratory conditions (25 ± 1 °C, 75 ± 5% RH, 16:8 [L:D] photoperiod). Using the age-stage, two-sex life table approach with Tetranychus urticae Koch as prey, results showed that total longevity was shortest in progeny of LC20-treated parents (males = 13.42 days; females = 13.94 days) compared with LC10 progeny (males = 15.06 days; females = 15.50 days). Fecundity, oviposition period, and net reproductive rate (R₀) declined significantly with increasing acaricide concentration. Intrinsic and finite rate were reported to be increased in the treatments (r: 0.159 vs. 0.199 day−¹; λ: 1.172 vs. 1.221 day−¹). Age-specific survival (lₓ), fecundity (mₓ), and reproductive value (vₓⱼ) curves indicated pronounced adverse effects of sublethal exposure on population performance. These findings demonstrate that even low concentrations of abamectin can compromise key life history traits of A. swirskii, potentially limiting its effectiveness in biological control programs. Thus, evaluating acaricide compatibility with natural enemies is critical for successful IPM implementation.

Abstract Investigating the potential effects of chemical pesticides on the biological performance of natural enemies is crucial for the successful implementation of integrated pest management programs. In the present study, the effects of low concentrations (LC10 = 5.14, LC20 = 12.55, and LC30 = 23.89 mg a.i./L) of bifenazate (Floramite® 24% SC) on the predation parameters of Phytoseiulus persimilis Athias-Henriot feeding on larvae and protonymphs of Tetranychus urticae Koch were investigated under laboratory conditions. The results indicated that the appropriate time interval for releasing the predator after the application of bifenazate (LC30 = 23.89 mg a.i./L) was at least 48 hours, as no obvious effects on its survival and predation parameters were detected. Furthermore, exposure to the low concentrations had no carryover effects on the predation performance of the offsprings. The age-stage specific predation rate (cxj) increased with increasing age and stage of individuals and had the highest value for adult females, although its peak value decreased with increasing concentration. The values of net predation rate (C₀), finite predation rate (ω), transformation rate (Qp), and stable predation rate (ψ) in the subsequent generation were not significantly affected when the female predators were exposed to the different concentrations. These results indicate that the different low concentrations of bifenazate had no negative effects on the predation performance of P. persimilis and its offspring. Therefore, their combination may play an important role in the sustainable management of T. urticae.