The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a well-known pest mite with an extensive host range worldwide. The control of T. urticae populations mostly relies on the application of synthetic acaricides or pesticides. Chlorfenapyr is a broad spectrum insecticide/miticide effective against agriculturally important pests. In this study, sublethal effects (LC10, LC20 and LC30) of this insecticide 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]. According to the obtained results, the LC50 value for females of T. urticae was 47.66 ppm. The egg incubation, protonymph, as well as deutonymph durations of both sexes were significantly reduced as a consequence of treatment with LC20 and LC30 of chlorfenapyr. In addition, our results indicated that oviposition period in LC10 lasted 9.62 days, which was closer to the control (9.73 days); while it significantly decreased with increasing the concentration from LC20 to LC30. Furthermore, LC20 and LC30 treatments decreased the fecundity of females by 55.5% and 61.6%, respectively. The values of both intrinsic (r) and finite rates of increase (λ) at LC20 and LC30 was significantly inferior to other experimental treatments. It could be concluded that along with the lethal doses, the sublethal concentrations of chlorfenapyr profoundly reduced the population growth rate of T. urticae.
Knowledge of the effects of pesticides on biological control agents is mandatory for the successful implementation of IPM programs. The aim of this study was to evaluate the effects of spirotetramat on the life table parameters of Neoseiulus californicus, under laboratory conditions [25 ± 2ºC, 70 ± 5% RH and 16:8 (L:D) h]. The experiments were carried out based on the leaf-dip technique. The experimental concentrations including 10000, 20000 and 30000 ppm of the spirotetramat were used in this study. The raw data was analyzed based on the age-stage, two-sex life table theory. The longevity, total life span, oviposition period, and total fecundity significantly decreased after exposure to concentrations of 20000 and 30000 ppm. The oviposition period was scored 26 days in the control cohort, which reduced to 22.87 days in the 30000 ppm. The total fecundity ranged between 29.45 and 39.46 (offspring/individual). Among the examined concentrations, the lowest values of the gross and net reproductive rates were 21.96 and 17.69 (offspring/individual), observed for the cohort treated with 30000 ppm concentration. Our findings showed the r and λ of N. californicus were not influenced by the different concentrations. The mean generation time (T) for control was the highest; the values for T varied from 18.35 days at control to 16.36 days at 30000 ppm. Therefore, it was concluded that spirotetramat can be introduced as a compatible pesticide alongside the predatory mite, N. californicus, which is an excellent tool that can be incorporated into the integrated pest management of T. urticae.
The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is one of the most important pests of agricultural products. Using chemical pesticides is one of the main methods for its management. Due to undesirable effects of synthetic pesticides, this research was conducted to achieve alternative safe compounds. In this study sublethal effect of Atropa belladonna herbal extract including LC 10 , LC 20 , LC 30 and distilled water were evaluated on biological parameters (such as r, λ, GRR, R 0 and T) of T. urticae. The experiments were done under laboratory condition at 25±2 °C, 60±5% RH, and a photoperiod
Estimating sublethal effects of acaricides on phytoseiid mites and their prey as a reliable approach in predicting the acaricides impacts is mandatory for IPM programs. The aim of this study was to evaluate the effects of spiromesifen on life history traits and demographic parameters of the offspring of Neoseiulus californicus and Tetranychus urticae under laboratory conditions [25 ± 2ºC, 70 ± 5% RH and 16:8 (L:D) h]. The experiments were conducted based on the leaf-dip technique. The crude data were analysed based on age-stage, two-sex life table analysis. The pre-adult and adult longevity of both sexes significantly reduced for N. califonicus and T. urticae with the concentration enhancing from LC20 to LC35. In addition, the oviposition period for both species significantly decreased as a consequence of treatment with LC25 and LC35 of spiromesifen. The minimal values of the total fecundity for N. califonicus and T. urticae were 16.58 and 19.35 (offspring/individual), respectively, which was related to LC35 concentration. Further, the lowest values of R0 and GRR of N. califonicus and its prey were 48.88 and 31.14 (offspring/individual) in LC35, respectively. However, the intrinsic rate of increase (r) and finite rate of increase (λ) were not significantly influenced by sublethal concentration in N. californicus while the r and λ were significantly reduced in T. urticae treated by LC20, LC25 and LC35. Therefore, spiromesifen could profoundly decrease the population growth rate of T. urticae but can not be considered as a compatible acaricide with N. califonicus because of its negative effect on the longevity, total lifespan, and reproductive periods and should not be used with this predatory mite in integrated pest management programs.
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