BIOLOGICAL-CONTROL OF BROAD MITE, POLYPHAGOTARSONEMUS-LATUS (BANKS), BY NEOSEIULUS-BARKERI HUGHES ON PEPPER

Augmentative releases of the predatory mite Neoseiulus (Amblyseius) barkeri Hughes (Acarina: Phytoseiidae) have been successfully used to control the broad mite Polyphagotarsonemus latus (Banks) (Acarina: Tarsonemidae) on many crops in greenhouses at The Land for more than 3 years. The functional response of N. barkeri to broad mite in the laboratory and the release rate for N. barkeri on pepper (Capsicum annuum L. 'Hungarian Wax') in greenhouses were studied. The functional response of N. barkeri adult females was determined on pepper leaf discs with prey density ranging from 5 to 60 adult broad mite females at 25 degrees C over a 24-h period. Predation data were described by a typical type II response curve with parameters of attack rate (a) = 1.1803 and handling time (T-h) = 0.0157. Cage experiments, which compared four release rates of N. barkeri, indicated that releasing 10 or more mites per plant can effectively reduce the broad mite population from more than 100 mites per leaf to zero in a week. Influx experiments, in which there was continuous immigration of the broad mite, showed that a single release of 5 N. barkeri adults per plant significantly reduced broad mite populations, but failed to prevent all plants from broad mite injury, and that three weekly releases of 5 N. barkeri adults per main stem provided adequate protection from broad mite injury for over 7 weeks. It is suggested that augmentative releases of N. barkeri can be an ecologically sound alternative strategy for broad mite control in greenhouses and that it may also provide some control of the western flower thrips [Frankliniella occidentalis (Pergande)] at the Same time. (C) 1994 Academic Press, Inc.