Population Dynamics of Frankliniella occidentalis on Different Rose Cultivars and Flowering Stages

Seasonal occurrence and damaged aspects of Frankliniella occidentalis (Pergande) on various rose cultivars were investigated from three greenhouses (one experimental greenhouse and two commercial greenhouses) during 1999 to 2000. In the experimental greenhouse, first detection of F. occidentalis on yellow sticky trap was observed in early April, gradually increased till early May and greatest densities occurred during June each year. In commercial rose greenhouses where insecticides were applied >2.2 times per month for the control of F. occidentalis, relatively low levels of F. occidentalis populations were captured on the traps. The population levels were 40% of the level of F. occidentalis populations collected from the experimental greenhouse. In preference of rose cultivar and color, yellow-colored cultivars were the most preferred by F. occidentalis and second was white flower. However, there was no preference difference within same colored cultivars. First inhabitation of F. occidentalis adults was observed at stage F2 (sepal uncovered the bud partly and corolla protruding from the calyx) of rose flowers. The number of adults was increased as the stage was developed from the stage F2 to F4 (flower began to senesce), but the proportions of adults were decreased as the stages were developed.