Incidence and preference of Frankliniella occidentalis (Thysanoptera: Thripidae) to different rose cultivars

Western flower thrips (WFT), Frankliniella occidentalis, is a major pest in rose crops worldwide. This pest causes considerable esthetic injuries to rose flowers, thus reducing their market value, which leads to economic losses. WFT attacks on rose cultivars are determined by environmental conditions and host-plant features such as resources supply, flower developmental stage, petal color, flower shape, and plant chemical cues. To recognize the possible role that chemical cues could play in WFT-rose interactions, WFT incidence in six commercial rose cultivars was studied in greenhouse plots for commercial growing, and WFT preference to these cultivars was evaluated in choice tests in daylight and darkness under laboratory conditions. Furthermore, the WFT responses to the cultivars' flower odors were evaluated in a bioassay using a Y-tube olfactometer. Differences in the incidence of WFT between rose cultivars were observed in the field. Additionally, the choice tests showed a difference in WFT preference between rose cultivars in daylight conditions but not in darkness. For the six cultivars, WFT showed positive chemotactic responses to one cultivar and negative chemotactic response to two cultivars in Y-tube olfactometry bioassay. The different results found among the incidence in the field, the laboratory choice tests, and the Y-tube olfactometry bioassays, show that chemical cues alone cannot explain the behavioral responses of WFTs to different cultivars in the field.