Persian Journal of Acarology

Abstract The European red mite, Panonychus ulmi (Acari: Tetranychidae) is one of the main pests of apple trees worldwide. The main purpose of this research was to study the repellent and lethal effect of Heracleum persicum Desf. and Trachyspermum ammi L. essential oils (EOS) on the European red mite. The EOS of H. persicum and T. ammi were extracted using a Clevenger device and by water distillation method. The mortality of the mites was evaluated after 24 hours and the lethality of each EO was calculated in contact and fumigant toxicity in an incubator at 26 ± 2 °C temperature, 16:8 h L:D, and 50 ± 5% RH. It was found that the LC50 values of EOS of H. persicum and T. ammi were 343.91 and 311.74 µL l-1 for contact toxicity, and 2.54 and 2.85 µL l-1 air for fumigant toxicity, respectively. With increasing the concentration of EOS, the death rate of mites was increased. Three different concentrations of the EOS from H. persicum and T. ammi were tested for their repellent effects on the European red mite. Results of the present study revealed, that the repellency rate increased with increasing concentration, meanwhile, the T. ammi EO had the highest repellency among the concentrations.

Abstract The sublethal effects of fenpropathrin on the oxalis spider mite, Tetranychina harti (Tetranychidae) were investigated. The results showed that, relative to the control group, sublethal doses of fenpropathrin significantly shortened the developmental duration of immature offspring in the LC15 group (P < 0.05) but significantly prolonged it in the LC30 group (P < 0.05). Furthermore, these sublethal exposures shortened the pre-oviposition period while prolonging the oviposition period of F1 female adult mites. Notably, a significant reduction in mean fecundity per female was observed only in the LC15 group compared to the control (P < 0.05). The cumulative survival rate curves and age-specific fecundity curves indicated that sublethal concentrations (LC15 and LC30) of fenpropathrin did not exert a clearly adverse effect on the survival or fecundity of Tetranychina harti. Both treatment groups exhibited higher net reproductive rates (R0) than the control. Similarly, the intrinsic rates of increase (rₘ) in the LC15 and LC30 groups exceeded that of the control, and the finite rates of increase (λ) in both treatment groups were also higher. In addition, the population doubling time (DT) was shorter in the treatment groups than in the control. These findings suggest that sublethal exposure to fenpropathrin may compromise its efficacy in controlling this mite population.

Abstract The transmaternal properties of diflovidazin were examined under laboratory conditions on Tetranychus urticae. To assess its transmaternal ovicidal effect, leaf discs were dipped in a 100 ppm diflovidazin solution, after which adult females were allowed to feed on the treated surfaces for either 2 or 48 hours. The females then laid eggs on an untreated surface over five consecutive 7-hour periods. Egg mortality was evaluated based on exposure duration and time elapsed since exposure. After being removed from the treated surface, 100% of the eggs laid by females in the first 7-hour period were non-viable. However, mortality—and thus the effect—gradually decreased in subsequent periods, with eggs laid after 28 hours exhibiting mortality levels comparable to naturally occurring rates. Notably, the length of the exposure period did not influence the rate at which egg mortality declined. The effect on egg production was also examined. Females were allowed to lay eggs on treated leaf discs, but the treatment did not significantly alter the number of eggs produced per female. These findings indicate that while diflovidazin effectively induces high egg mortality, it does not reduce overall egg production. Our results suggest that diflovidazin temporarily sterilizes females, likely because developing eggs absorb the active substance from the female's system.

Abstract This study investigates the lethal and sub-lethal effects of the pesticides fluxametamide and Sero-X on the predatory mite, Neoseiulus californicus (McGregor). As a key biocontrol agent, N. californicus is crucial in regulating mite pest populations and small insects like thrips. Understanding the effects of these pesticides is essential for maintaining effective biological control strategies. In an integrated pest management (IPM) program, selecting low-risk pesticides that target pests while preserving beneficial organisms is critical. To assess these effects, bioassay tests were conducted under controlled laboratory conditions (25 ± 2 °C, 65 ± 5% RH, and a 16:8 light-dark photoperiod). Lethal bioassay test results showed that the LC50 values of fluxametamide and Sero-X on adults of N. californicus were 1421 mg/L and 2169 mg/L, respectively. The results showed that exposure to the LC30 concentration of either fluxametamide or Sero-X significantly affected the predator’s reproduction and developmental parameters. Both treatments reduced life table parameters (r, R₀, λ, and GRR) while increasing generation time (T) compared to the control. Additionally, maternal exposure influenced progeny life history in varied ways. These findings highlight the need for sustainable pest management that minimizes chemical impact while preserving ecological balance, ensuring natural predators remain effective in agriculture.