Banker Plants: Evaluation of Release Strategies for Predatory Mites

Abstract

Abstract Spider mites (Tetranychidae) are among the most injurious pests of commercial landscape plant nurseries. The introduction of predaceous mites (Phytoseiidae) into nursery crops for control of spider mites can be an effective alternative to pesticides. We sought to evaluate the use of banker plants as a method of rearing and dispersing predatory mites for the control of spider mites in landscape nursery systems. Banker plants include any plant addition that aids in development and dispersal of predators for control of herbivorous pests. Addition of the predatory mite Neoseiulus fallacis (Garman) into spider mite infested arborvitae and rhododendron banker plants held in replicated greenhouse cubicles resulted in more predatory mites dispersing to spider mite infested plants downwind than were originally inoculated. To improve persistence and subsequent dispersal of predatory mites in an arborvitae banker plant, we evaluated the use of adding supplemental prey (spider mites) and applying a portion of the plant foliage with a pyrethroid to provide a refuge for the prey. Reintroduction of prey increased the dispersal duration of N. fallacis but the pyrethroid-based refuge did not. Predatory mites dispersing from arborvitae banker plants of approximately 1.25 m (4.1 ft) tall were collected from receiver plants at 10, 20 and 30 m (10.9, 21.9 and 32.8 yd) down wind. Integration of a banker plant system into a landscape nursery operation is discussed.