Essential oils reduce the emergence of Spodoptera littoralis

Essential oils of Nepeta cataria and Piper aduncum reduced the emergence of adult Spodoptera littoralis after sublethal exposure in the laboratory. Piper aduncum oil also showed greater topical toxicity. The median lethal dose reached 0,075 microliters of essential oil per insect, compared to 0,196 microliters for Nepeta cataria.

The researchers applied the products to fourth-instar larvae and assessed mortality after 24 hours. Piper aduncum showed a median lethal dose approximately 2,6 times lower. Mortality increased with the dose in both treatments.

At a fixed sublethal dose of 0,020 microliters of essential oil per insect, developmental duration and body weight showed no significant differences. Pupa formation also did not change. Adult emergence fell from 100% in the control to 83,3% with Nepeta cataria and 71,4% with Piper aduncum. The difference between the two oils did not reach statistical significance.

Body dimensions

Body dimensions varied according to developmental stage and treatment. Researchers recommend caution in this interpretation, as the pre-imaging measurements involved limited sampling and the number of adults varied depending on the emergency.

Chemical analysis identified 1,8-cineole as the main component of Nepeta cataria, at 39,2%. Piper aduncum showed 46,5% dillapiole. The study points to the need to include late effects in the evaluation of botanical insecticides. The assays were carried out under controlled conditions and still require validation under cultivation conditions (doi 10.1016/j.napere.2026.100230).