Evaluation of medium treatments for management of Frankliniella occidentalis (Thripidae : Thysanoptera) and Bradysia coprophila (Diptera : sciaridae)

Two greenhouse experiments, each comprising two trials, were conducted to e valuate medium drenches of insect growth regulators and conventional insect icides to reduce emergence of adult western flower thrips, Frankliniella oc cidentalis (Pergande), and fungus gnats, Bradysia coprophila (Lintner) from the medium. In the insect growth regulator trials, diflubenzuron and pyrip roxyfen provided the greatest reduction in thrips emergence, and fenoxycarb , pyriproxyfen and azadirachtin resulted in the most significant reduction of fungus gnat emergence. Treatments with the contact insecticides, methioc arb and chlorpyrifos, resulted in the greatest reduction of thrips and fung us gnat populations. These data suggest that fungus gnats are susceptible t o many compounds used in commercial greenhouse production. Even though medi um drenches are not currently used for thrips management, drenches with dif lubenzuron, pyriproxyfen, methiocarb and chlorpyrifos could aid in reducing thrips populations in greenhouse management programs. (C) 2001 Society of Chemical Industry.