PREDATORY MITES RELEASED ON TRANSPLANTS CAN PROTECT GREENHOUSE-GROWN PEPPERS FROM EARLY BROAD MITE INFESTATIONS

The minute broad mite, Polyphagotarsonemus latus (Banks), can cause serious damage to peppers (Capsicum annuum) when infestations occur at early plant developmental stages. A first study was set to evaluate biological control strategies during seedling development. Timing of release of Neoseiulus californicus McGregor, a commercially reared predatory mite, was investigated in scenarios of pest and predator presence to simulate preventive and curative strategies of control. Undamaged seedlings were produced when two predators per seedling were released preventively. Curative control strategies were not effective for producing undamaged or broad mite-free transplants. Further studies were carried to evaluate the effectiveness of N. californicus on pepper seedlings that host a few broad mites and are transplanted into the production greenhouse. N. californicus released at different times and densities, and conventional control methods (micronized-sulfur sprays) were evaluated for pest control, plant damage, and fruit yield. Yields of red fruits from plants with four predators per plant released at any of the release times (a week before, at, or four days after transplanting) or with sulfur sprays were not significantly different from an uninfested control treatment. Releases of two predatory mites per plant led to yields similar to the uninfested control only when introductions were a week before transplanting, while later introductions led to serious plant damage and significantly lower yields. Early broad mite infestations in pepper crops grown in greenhouses might be effectively controlled with N. californicus released at early seedling developmental stages in the nursery and at transplanting in the fruit production greenhouse.