Oviposition-deterrent activity of p-methyl benzaldehyde and 2-hydroxy-5-methoxybenzaldehyde from the extract of Periplocae cortex for the control of Spodoptera frugiperda.

Background: The invasion of Spodoptera frugiperda into China has caused serious losses to the food industry and has developed varying degrees of resistance to various chemical pesticides. Developing new plant-based pesticides is of great significance for the sustainable management of S. frugiperda.

Results: p-Methyl benzaldehyde, 2-hydroxy-5-methoxybenzaldehyde and 2-hydroxy-4-methoxybenzaldehyde elicited strong electroantennogram (EAG) reactions from S. frugiperda adults. In particular, 14.4 mg/mL p-methyl benzaldehyde produced the strongest EAG reaction. At this concentration, olfactory selection results showed significant repellent activity against adults, while 0.09 mg/mL had significant attractant activity against males. 2-Hydroxy-5-methoxybenzaldehyde had significant attractive effects at 2.40, 7.20, 14.40 mg/mL. However, 0.80 and 14.4 mg/mL showed significant repellent effects on oviposition selection after treatment with p-methyl benzaldehyde, while 0.09 mg/mL showed significant attractant activity, with an oviposition index of 0.48 ± 0.12. Three treatments of 2-hydroxy-5-methoxybenzaldehyde showed significant repellent activity against the oviposition selection. In addition, exposure to these two substances could significantly inhibit the number of spermatophores and eggs laid by a single female.

Conclusion: p-Methyl benzaldehyde and 2-hydroxy-5-methoxybenzaldehyde in the secondary metabolites of the Chinese medicinal herb Periplocae cortex have obvious regulatory effects on the olfactory behavior and oviposition selection of Spodoptera frugiperda and significantly inhibit fertility. This result is helpful to understand the relationship between non-host plant secondary metabolites and insects, lay the foundation for new active substances as insect behavior regulators. © 2025 Society of Chemical Industry.