Encapsulation of a N-Alkylamide-Enriched Fraction from Acmella oleracea and Its Efficacy Against Tuta absoluta, the Invasive Key Tomato Pest

The South American tomato pinworm Tuta absoluta is the key pest of tomato crops in almost all regions where tomato is cultivated. In recent years, control methods with lower environmental impact, as alternatives to chemical treatments, have increasingly been adopted. Among them the use of plant-based insecticides for the control of arthropods represents a potential control strategy. In this framework, the plant extract from Acmella oleracea with a N-alkylamide-enriched fraction (AEF) seems to be a successful tool in integrated pest management. This product was prepared by combining two eco-friendly techniques, namely supercritical CO2 extraction and wiped-film short path molecular distillation, and encapsulated into stable nanoemulsions (NEs) at different concentrations. After assessing the phytotoxicity on tomato plants, the AEF-NEs were tested against eggs, larvae and adults of T. absoluta in laboratory bioassays. The results showed that AEF-NEs inhibited egg hatching and reduced larval survival and adult emergence. Moreover, a significant ovideterrent effect was shown comparing different concentrations of AEF-NE with distilled water. This study indicates that the AEF-NEs could represent a promising alternative to synthetic pesticides against T. absoluta to reduce the insecticide resistance in the pest populations.