Management of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) in the greenhouse

The relationship of the time interval between insecticide applications to Frankliniella occidentalis (Pergande) damage to gloxinia (Sinningia speciosa Benth & Hook) flowers, population density of F. occidentalis, and flower phytotoxicity was determined through greenhouse experiments. Application of abamectin and chlorpyrifos at 5- and 10-day intervals and application of cyfluthrin at 5-day interval held thrips flower injury to a tolerable level. For abamectin and cyfluthrin, the number of thrips per flower decreased as the interval between applications decreased. The amount of insecticide phytotoxicity to flowers increased as the application interval decreased. The potential of gloxinia seedlings as indicator plants for tomato spotted wilt virus (TSWV) was evaluated. Two thrips per seedling were sufficient to transmit the virus to gloxinia seedlings. Yellow cards increased attractiveness of gloxinia seedlings to F. occidentalis. However, gloxinia without yellow cards developed TSWV symptoms at the same time and at the same rate as the gloxinia with yellow cards.