Contact Toxicity, Antifeedant Activity, and Oviposition Preference of Osthole against Agricultural Pests.

Osthole, the dominant bioactive constituent in the , has shown acute pesticidal activities. However, its detailed toxicity, antifeedant, and oviposition preference effects against agricultural pests have not been fully understood, limiting its practical use. This study aimed to investigate the contact toxicity, antifeedant activity, and oviposition preference of osthole against three agricultural pests (, , and ). Our results showed that the (L.) Cusson (CMC) has a high osthole content of 11.4 mg/g. Osthole exhibited a higher level of acute toxicity against the to four other coumarins found in CMC. It showed significant pesticidal activity against and first-instar nymphs and adults in a dose-dependent manner but not against adults. Osthole exposure reduced the fecundity and prolonged the developmental time of the and . Leaf choice bioassays revealed potent antifeedant activity in the and . Furthermore, the female showed a distinct preference for laying eggs in mango juice with 0.02 mg/mL osthole at 48 h, a preference that persisted at 96 h. These results provide valuable insights into the toxicity, repellent activity, and attractant activity of osthole, thereby providing valuable insights into its potential efficacy in pest control.