Development of Thrips Repellents, and Their Combined Application with Aggregation Pheromones in a Push–Pull Strategy to Control Frankliniella occidentalis

Simple SummaryInsect repellents have been intensively studied due to growing interest in environmentally safe pest control methods. Numerous repellent compounds have been reported to be effective against western flower thrips,Frankliniella occidentalis. However, few studies have been conducted to test the repellent activity and control efficacy of these compounds against thrips in the field. In this study, we investigated the repellent effects of two plant volatiles, α-pinene and eucalyptol, onF. occidentalisusing cage and field experiments. Our results showed that both α-pinene and eucalyptol at high doses significantly reduced the egg-laying ofF. occidentalison host plants in cage experiments. In addition, the application of eucalyptol EC and α-pinene EC reduced the field population ofF. occidentalis, with eucalyptol EC performing better. The combination of aggregation pheromone traps and repellent eucalyptol spray also significantly reducedF. occidentalispopulations in the field. Our results provided effective eco-friendly control methods for the integrated pest management ofF. occidentalis.Western flower thrips,Frankliniella occidentalis(Pergande), is a serious pest of horticultural and agronomic crops. Using plant-released semiochemicals to control thrips is one eco-friendly control method for their management. In this study, to develop repellents and an attractant–repellent push–pull strategy forF. occidentalis, we investigated the effects of α-pinene and eucalyptol on their oviposition on pepper plants in cage experiments and evaluated the control efficiency of repellents on them in pepper fields. The control efficacy of a combination of aggregation pheromone attractants and plant volatile repellents was also investigated. The results showed that spraying eucalyptol (at the dose of 200 μL) and α-pinene (at the dose of 100 μL) significantly reduced the oviposition behavior ofF. occidentalisin cage experiments. Field results showed that the application of eucalyptol and α-pinene could significantly reduce the population ofF. occidentalisin the field, with the highest control efficacy of 80.96% and 66.66%, respectively. Furthermore, a push–pull strategy combining thrips-repellent eucalyptol and aggregation pheromone lures was an effective strategy to suppress a population of thrips in the field, with the highest control efficacy of 81.95%. The repellents and push–pull strategy developed here provided an effective method for the eco-friendly control ofF. occidentalis.