Preparation and Application of a Composite Formulation of Mint Essential Oil Nanoemulsion

To develop an efficient and low-toxic green plant-based insecticide and address the issues of rapid volatilization and poor stability of mint essential oil, this study prepared a mint essential oil nanemulsion composite formulation using Tween 80 as the surfactant and propylene glycol as the cosurfactant. The insecticidal activity of the formulation was tested against fall armyworm, Spodoptera frugiperda and corn aphid, Rhopalosiphum maidis. Results showed that the optimal formulation consisted of a surfactant to cosurfactant mass ratio of 3:1 and a mixed surfactant to mint essential oil mass ratio of 9:1. The formulation exhibited good stability after dilution and centrifugation tests. Bioactivity assays indicated that the formulation effectively inhibited and killed fall armyworm eggs. At a concentration of 6.66 mg/mL, it completely inhibited the hatching of fall armyworm eggs and achieved 100% mortality of corn aphid nymphs and adults. This mint essential oil nanemulsion composite formulation demonstrated excellent performance and significant bioactivity, providing a new formulation option and technical support for the green control of fall armyworm and aphids on corn.