Western Flower Thrips, Frankliniella occidentalis (Thysanoptera: Thripidae): Evaluation of Potential Attraction to Vanilla Extract under Laboratory and Greenhouse Conditions

Abstract

Plant-derived essential oils or extracts and their associated volatiles can serve as insect attractants to enhance adult captures when used as whole plants or extracts that are incorporated onto colored sticky traps. In our study, we initially assessed the attractiveness of western flower thrips (WFT) (Frankliniella occidentalis) adults to vanilla extract in the laboratory using choice and no-choice experiments by comparing one (0.05 mL) and two (0.10 mL) drops of vanilla extract (0.029% and 0.059%, respectively). In the choice experiments, a drop of water and drop of vanilla extract were placed on opposite sides of a petri dish. One WFT was placed in the center of the petri dish, and observations were made on whether there was preferential movement to the water or vanilla extract. For the no-choice experiments, one petri dish only contained a drop of water, whereas another petri dish only contained a drop of vanilla extract. One WFT was placed into each petri dish and movement was observed to assess whether the WFT moved toward the water or to the vanilla extract. We then determined if yellow sticky cards containing vanilla extract were more attractive to WFT adults than those with water, by using the number of adults captured on yellow sticky cards as an estimate under greenhouse conditions. Western flower thrips adults were not attracted to vanilla extract based on the results associated with the choice and no-choice tests conducted under laboratory conditions with no differences in selection between vanilla extract and water. In addition, there was no evidence that inoculating yellow sticky cards with vanilla extract enhanced the number of adults captured on yellow sticky cards. Overall, the use of vanilla extract in attracting WFT adults to yellow sticky cards is not justifiable under the parameters of our study.