Encapsulation of Carlina acaulis essential oil and carlina oxide to develop long-lasting mosquito larvicides: microemulsions versus nanoemulsions

Abstract Carlina acaulis root essential oil (EO) is one of the most potent mosquito larvicides (LC 50 < 2 ppm). This EO mainly composed carlina oxide (> 90%). Poor water solubility and rapid degradation from UV light oxygen in environment limit real-world use this EO. Herein, we developed nanocarrier-based formulations, namely micro- nanoemulsions (ME NE, respectively) containing C. or (both at 0.5%) as active ingredients (a.i.). The larvicidal activity ME NE was evaluated against Culex quinquefasciatus . highest achieved by 0.5% (M1); its LC 50(90) 579.1 (791.3) µL L −1 Sublethal effects a.i. were assessed testing both 16 , 30 90 on larvae exposed to each product for 1–7 h, then monitoring mortality 18 days. At variance with EO, application, even led 100% encapsulated form scarcely toxic human keratinocytes (HaCaT) fibroblast (NHF A12) cell lines. acute toxicity (M1) also Wistar rats through oral administration; LD 1098 mg kg bw, whereas ME, 5000 bw (considered upper establish safety mammals), not toxic. study highlights outstanding efficacy developing long-lasting safe Cx.