Nanoemulsion: A Green initiative for pest management

Abstract

Brinjal or eggplant is a very important crop (vegetable) of sub-tropics and tropics of India. This plant is highly infested by Henosepilachna vigintioctopunctata (Coleoptera: Coccinellidae). It is a polyphagous pest in nature; the adult and grub stages cause severe damage to the plants by feeding on its leaves, flowers, and vegetables and create heavy economic losses. Though the beetles could be controlled using synthetic pesticides, indiscriminate use of pesticides in the field causes problems such as pest resistance, environmental and health hazards, etc. These pave the way for the development of effective eco-friendly pest control measures. Plant-based essential oils are used against these insect pests, as they constitute a rich source of bioactive components and are reported to have many biological properties. Recently, essential oils were formulated as nanoemulsions and developed for their effectiveness and eco-friendly nature. In this study, the oil-in-water (O/W) nanoemulsion of Mentha piperita was prepared by the ultrasonication method at different concentrations and examined for stability study. The stable nanoemulsion was characterized by DLS and was reported to consist of a mean droplet size of 10.84 nm, PDI was 0.1, and zeta potential was -45 mV, which proved the good stability of the nanoemulsion. To assess the efficacy of the formulated nanoemulsion and bulk emulsion, it was screened against the adult beetles, Henosepilachna vigintioctopunctata, at different concentrations for 96 hours. The resulted LC50 value of nanoemulsion was 15.84%, which was found to be very effective than the LC50 value of bulk emulsion, which was 60.25%. Hence from the results obtained, Mentha piperita nanoemulsion may be used as an organic pesticide because of its higher efficacy against the adult beetles, Henosepilachna vigintioctopunctata.