Development of Thrips Repellents, and Their Combined Application with Aggregation Pheromones in a Push–Pull Strategy to Control Frankliniella 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 for F. 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 of F. occidentalis in cage experiments. Field results showed that the application of eucalyptol and α-pinene could significantly reduce the population of F. occidentalis in 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 of F. occidentalis.