Preparation of fenpropathrin nanoemulsions for eco-friendly management of Helicoverpa armigera: Improved insecticidal activity and biocompatibility

Abstract

In this study, the ratio, dosage of surfactants, and emulsification process were selected. The prepared fenpropathrin nanoemulsion exhibited suitable stability and remarkable insecticidal activity against Helicoverpa armigera. The optimal formula in compliance with the standard of FAO was obtained. Fenpropathrin (10 wt%) and ethoxylated castor oil (EL-10: EL-40 = 2: 1, 9 wt%) were dissolved, mixed with hydrocarbon solvent (S-200, 8 wt%) and replenished with deionized water to obtain 100 wt%. The nanoemulsion droplets showed small contact angle and high adhesion work onto corn leaves, indicating that the nanoemulsions exhibited excellent wetting, adhesion and stretching capabilities. Compared with commercial emulsifiable concentrate (EC), the nanoemulsion had lower LC50 (50.01 mg L−1) against the third instar larva of Helicoverpa armigera. This was due to the body of larvae becoming completely darkened, shriveled and incapacitated shortly after treatment. The LC50 of the fenpropathrin nanoemulsion on Eisenia fetida was 96.60 and 47.99 mg kg−1 after 7 and 14 days, respectively. This indicated low toxicity to E. fetida. The L02 cell viability after 24 and 48 h of nanoemulsion treatment was 85.32 % and 68.95 %, respectively. In addition, the fenpropathrin nanoemulsion showed a lower apoptosis rate against L02 cells (8.52 %) than EC (63.18 %) after 24 h, indicating that the nanoemulsion had low cytotoxicity against L02 cells. In general, the utilization and environmental performance of pesticides were improved, with less cytotoxicity. This study will facilitate the preparation and application of nanoemulsions for lipophilic pesticide to enhance insecticidal activity, lower cytotoxicity and improve environmental compatibility.