The effects of mixed prey (<i>Tetranychus turkestani</i> and <i>Tetranychus truncatus</i>) on the growth, development, and fecundity of <i>Neoseiulus bicaudus</i>

In biological control, prey type, structure, and abundance influence predator populations. The predatory mite Neoseiulus bicaudus Wainstein (Acari: Phytoseiidae) can control both Tetranychus turkestani Ugarov et Nikolskii (Acari: Tetranychidae) and Tetranychus truncatus Ehara (Acari: Tetranychidae), which often coexist in nature. Does N. bicaudus feeding on both prey species in mixed field populations experience enhanced population growth or remain unaffected by prey type? This study used the age-stage 2-sex life table theory to examine the developmental and reproductive characteristics of N. bicaudus fed the 2 prey (T. truncatus: T. turkestani at 1:20, 1:10, and 1:5 ratios) and a single prey diet (T. turkestani is a dominant species for crops such as cotton in Northern Xinjiang). The results showed that, compared to a single prey diet (where the preadult stage duration 5.367 d, intrinsic rate of increase (r) = 0.198 d-1, finite rate of increase (λ) = 1.219 d-1, and mean generation time (T) = 12.81 d), the mixed prey diet significantly shortened the preadult stage, increased fecundity, and enhanced the values of r and λ, while shortening T. The population had the highest intrinsic rate of increase at a ratio of 1:5 (preadult stage = 4.906 d, r = 0.245 d-1, λ = 1.277 d-1, and T = 11.58 d). Compared to single-prey feeding, mixed prey ratios of 1:20, 1:10, and 1:5 increased population growth by 1.39, 2.72, and 6.59 times, respectively. Therefore, mixed prey enhances the development and reproduction of N. bicaudus, thereby further optimizing its mass rearing and field release.