Management of spider mite Tetranychus cinnabarinus (Boisduval) (Tetranychidae) infestation in cotton by releasing the predatory mite Neoseiulus pseudolongispinosus (Xin, Liang and Ke) (Phytoseiidae)

Mean seasonal average densities of spider and predatory mites in all cotton treatments using different numbers of plants and different growth stages of the crop. [Display omitted] ► Biocontrol of Tetranychus cinnabarinus was investigated by using Neoseiulus pseudolongispinosus. ► Predator was applied using different plant numbers of cotton and timing of release. ► Populations of mites during early and mid-season were significant from late release. ► Populations of mites differed significantly when every third plant was treated. ► Release of predator to reduce pest at early stage is useful if every plant treated. Biological control of the spider mite Tetranychus cinnabarinus (Boisduval) (Tetranychidae) in an open-field cotton crop (Gossypium hirsutum L.) by releasing the predatory mite Neoseiulus pseudolongispinosus (Xin, Liang and Ke) (Phytoseiidae) was investigated. The objectives were to determine the predatory efficiency of N. pseudolongispinosus released during different growth stages of the cotton and the different numbers of plants treated. The factors evaluated were release of predatory mites at a constant rate of five predators per plant using different plant numbers of cotton (every plant or every second or third plant treated) and timing of predator release (early, middle and late season releases). All predator released treatments were compared with a “no predator released” (control) trial. Based on treatment applications, the experimental data collected from biologically managed cotton fields and the untreated control showed significant differences in population densities of pest and predatory mites. Overall, the combined populations of both mites were not significantly different during early and mid-season releases, but varied significantly from late releases of predacious mite. The results also showed that populations of both pests and predators were not significantly different when each cotton plant and every second plant was treated with predator but differed significantly when every third plant was treated, where increased numbers of T. cinnabarinus and decreased N. pseudolongispinosus were observed. Consequently, field release of the predaceous mite N. pseudolongispinosus to reduce the incidence of T. cinnabarinus at an early growth stage of cotton is a potentially useful pest management strategy if every plant is treated with predator.