Persian Journal of Acarology

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 supply of pollens as an alternative food can enhance the performance of phytoseiid predatory mites. The study determined the effects of three different pollens (sunflower, tamarix, and common mallow) as supplementary diets on the life table parameters and predation rate of Neoseiulus californicus McGregor (Acari: Phytoseiidae) in the absence and presence of Tetranychus urticae Koch (Acari: Tetranychidae) eggs. The chemical compositions of the pollens were also analyzed. The results showed that the fecundity of N. californicus on T. urticae in the presence of pollen was significantly higher than that on pollen alone. The intrinsic rate of increase (r) on T. urticae in the presence of tamarix and common mallow pollens (0.131 and 0.132 day⁻¹, respectively) was significantly higher than those recorded on the other diets. The net reproductive rate (R₀) varied from 0.585 offspring (on sunflower pollen) to 8.465 offspring (on tamarix pollen + T. urticae). The cohort reared on common mallow pollen + T. urticae had the highest values of both intrinsic rate and the finite rate of increase, followed by tamarix pollen + T. urticae. The predation rate of T. urticae by N. californicus fed on tamarix pollen was the highest compared to other pollens. Tamarix pollen had the highest protein content, while sunflower pollen contained higher levels of lipid, phenol, and flavonoid compounds. Due to its higher protein content, tamarix pollen had favorable effects on the survival, development, fecundity, and predation rate of N. californicus. Tamarix pollen can be used as a supplementary medium alongside T. urticae, since the treatment with tamarix pollen + T. urticae eggs showed most of the superior parameters. Therefore, N. californicus reared on tamarix pollen can be helpful in controlling T. urticae.

Abstract The two-spotted spider mite Tetranychus urticae Koch, the date palm dust mite Oligonychus afrasiaticus (McGregor), and the citrus brown mite Eutetranychus orientalis (Klein) of family Tetranychidae are key pests of fruit trees, field crops, and ornamentals that cause significant yield losses. The purpose of this research was to assess the effect of three constant temperatures (22, 27, and 32 °C) on the developmental time, life-table parameters, and consumption rate of the predatory beetle Stethorus gilvifrons (Mulsant) on maize leaf disks with T. urticae, O. afrasiaticus, and E. orientalis as food. The results indicated a significant difference between the three different temperatures and prey types. The shortest developmental time was recorded on T. urticae (9.30 and 10.10 days) at 32 °C, while the longest was on E. orientalis (23.34 and 22.50) at 22 °C for females and males, respectively. The shortest female longevity was on E. orientalis (21.14 days) at 32 °C, and the longest was 39.12 days on T. urticae at 22 °C. The fecundity increased as temperature increased, from 114.6 eggs with a daily rate of 3.81 eggs per female/day at 22 °C to 235.0 eggs with a daily rate of 10.78 eggs per female/day at 32 °C on T. urticae. The highest net reproductive rate (R₀), intrinsic rate of natural increase (r_m), and finite rate of increase (λ) were recorded at 32 °C, whereas the lowest values were recorded at 22 °C when predatory beetles S. gilvifrons were fed on three prey diets. Gross reproduction rate (GRR) recorded the highest value (132.8 offspring/individual) when fed on T. urticae at 32 °C and the lowest value (55.30 offspring/ individual) when fed on E. orientalis at 22 °C. The highest consumption rate of adult males and females was 226.8 and 245.4 individuals when fed on O. afrasiaticus at 22 °C, while the lowest was 123.6 and 133.8 individuals on E. orientalis at 32 °C. Thus, the results obtained here revealed that temperature and prey diets influence the developmental rate and reproduction of S. gilvifrons. Additionally, T. urticae is better for mass rearing of S. gilvifrons than O. afrasiaticus and E. orientalis as food.