Promising nanoemulsion of Baccharis spartioides essential oil combined with lavender hydrolate: Insecticidal and repellent activity against Drosophila suzukii

Abstract

The use of conventional insecticides to control pests has caused several harmful effects on human and environment health. Therefore, bioinsecticides based on essential oils have emerged as a sustainable alternative for crop protection. The present study evaluates the chemical composition and its influence on the bioactivity of Baccharis spartioides (pichana) essential oil against Drosophila suzukii, an invasive pest that infests fine fruits. The chemical analysis showed that limonene (40.74%) was the major constituent in B. spartioides and the LC50 was 106.54 (95% CI: 91.61–127.24) µg/cm2 (contact exposure model). Moreover, pichana essential oil showed insecticidal and repellent action on D. suzukii adults. To overcome the inherent limitations of essential oils, a nanoemulsion was developed using lavender hydrolate as an innovative aqueous dispersing phase. Interestingly, the nanoemulsion exhibited a droplet size of 15.61 nm and a polydispersity index (PDI) of 0.224. Its stability was evaluated over a four-month storage period. This formulation improved the solubility, stability, and bioavailability of active compounds, enhancing efficacy in contact toxicity assays. Notably, insect mortality treated with the nanoemulsion was seven times higher than its component separately, pichana essential oil and lavender hydrolate. Previous studies have reported essential oil nanoemulsions for pest management, generally using distilled water as the aqueous phase. However, the present study explores the use of hydrolates as the aqueous phase. To our knowledge, this is the first report of B. spartioides essential oil nanoemulsions formulated with hydrolates for the management of D. suzukii.