Evaluation of the Predatory Mite Neoseiulus barkeri against Spider Mites Damaging Rubber Trees

The spider mites Eotetranychus sexmaculatus, Eutetranychus orientalis and Oligonychus biharensisin are severe pests of rubber trees in China. The predatory mite Neoseiulus barkeri has been found to be a natural enemy of these three pests, while nothing is known about the biological performance of this phytoseiid predator against these phytophagous mites. In this study, the development, survivorship, reproduction, adult longevity, fecundity, sex ratio and population growth parameters of N. barkeri fed on these pests were evaluated in comparison to the factitious prey Tyrophagus putrescentiae in the laboratory at 25 ± 1 °C, 75 ± 5% relative humidity and a 12:12 (L:D) h photoperiod. The results showed that N. barkeri could develop from egg to adult and reproduced successfully on the three preys. The survival rate of N. barkeri from egg to adult was higher when fed on E. orientalis (100%) and T. putrescentiae (100%) than when fed on O. biharensisin (93.60%) and E. sexmaculatus (71.42%). The shortest and longest generation time for N. barkeri were observed on E. orientalis with 6.67 d and E. sexmaculatus with 12.50 d, respectively. The maximum fecundity (29.35 eggs per female) and highest intrinsic rate of increase (r_m = 0.226) were recorded when N. barkeri fed on E. orientalis, while feeding on E. sexmaculatus gave the minimum fecundity (1.87 eggs per female) and lowest reproduction rate (r_m = 0.041). The values of these parameters for N. barkeri evaluated on O. biharensisin were found to be comparable to those obtained on T. putrescentiae. The sex ratio of N. barkeri progeny on the preys mentioned above, apart from O. biharensisin, was female biased. According to the findings, N. barkeri could serve as a promising biocontrol agent against E. orientalis and O. biharensisin, and possibly E. sexmaculatus on rubber trees.