Behavioral, Electrophysiological, and Toxicological Responses of Plutella xylostella to Extracts from Angelica pubescens

Simple Summary Plutella xylostella is one of the most destructive insect pests affecting cruciferous vegetables. The use of various plant extracts for controlling this pest is increasing in popularity, as they are multi-bioactive, biodegradable, and ecologically safe. In this study, we evaluated the insecticidal oviposition deterrence and repellent activities of Angelica pubescens extract and its compounds against P. xylostella. The A. pubescens extract, caryophyllene oxide, and 3,4-dimethoxycinnamic acid, have been proven to have insecticidal and oviposition deterrent activities against P. xylostella. The A. pubescens extract and caryophyllene oxide also mediate P. xylostella repellence. Overall, our results highlighted the potential of A. pubescens extract, caryophyllene oxide, and 3,4-dimethoxycinnamic acid in controlling P. xylostella and in the development of effective eco-friendly "inhibit and kill" insecticide formulations. Plutella xylostella L. is a destructive pest affecting cruciferous vegetables, causing massive economic losses worldwide. Plant-based insecticides are considered promising insect control agents. The Angelica pubescens extract inhibited female oviposition, with an oviposition deterrence index (ODI) of 61.65% at 12.5 mg/mL. We aimed to identify the bioactive compounds in A. pubescens extract. The compounds from A. pubescens extract were analyzed using LC-MS techniques. The toxicity and behavioral responses of larvae and adults of P. xylostella to ten compounds were investigated. We found that the caryophyllene oxide and 3,4-dimethoxycinnamic acid inhibited female oviposition; the ODIs were 98.31% and 97.59% at 1.25 mg/mL, respectively. The A. pubescens extract, caryophyllene oxide, and 3,4-dimethoxycinnamic acid caused larval mortality, with LC50 values of 21.31, 4.56, and 5.52 mg/mL, respectively. The EAG response of females was higher than that of males under A. pubescens extract conditions, while the EAG response of males was higher than that of females in caryophyllene oxide and 3,4-dimethoxycinnamic acid conditions. The A. pubescens extract and caryophyllene oxide showed repellent activity against both female and male adults, while the 3,4-dimethoxycinnamic acid did not elicit any notable behavioral responses from P. xylostella adults. A. pubescens extract and caryophyllene oxide are potential insecticides, oviposition deterrents, and behavioral regulators against P. xylostella, and they could be potential candidates for the development of biological insecticides to control P. xylostella.