Predatory efficacy of Orius strigicollis (Hemiptera: Anthocoridae) against Tetranychus urticae (Acarina: Tetranychidae) on strawberry

In this study, the predatory efficacy of Orius strigicollis (Poppius), a predacious flower bug, against the two-spotted spider mite (TSSM), Tetranychus urticae Koch, on strawberry (Fragaria ananassa) was investigated. Our results showed that release of 2, 4, 6, and 12 neonates of O. strigicollis per strawberry plant could suppress 58.9, 72.6, 88.6, and 92.8% of T. urticae, respectively, at 14days after treatment. A single release of 12 neonate bugs per plant achieved and maintained, over a period of 3months, 82% to 98% control of T. urticae population. A biweekly release of 6 neonate bugs per plant; likewise, suppressed ca. 90% of T. urticae population throughout the same period. However, predatory efficacy was reduced by an over-release of predators which may cause cannibalism as well as lower possibility of finding prey. Since the released neonates survived well to adults with offspring that retained their predatory ability, this study has demonstrated that O. strigicollis is a predator with good potential for sustainable suppression of T. urticae on strawberry, and one application of O. strigicollis neonates at a predator:prey ratio of 1:200 egg plus motile TSSM or 1:60 motiles per strawberry plant promises a season-long control and substantial management of spider mite infestation. Both of nymph and adult Orius strigicollis could effectively forage the egg and motile of Tetranychus urticae. [Display omitted] •Control efficacy of Orius strigicollis against TSSM might be affected by rainfalls.•Neonates survived to adults with offspring that retained their predatory ability.•Over-release may cause cannibalism as well as lower possibility of finding prey.•Single release may ensure a season-long control with a minimum labor and cost.•A rate of one neonate against 60 motile TSSM in early infestation was proposed.