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 a heavy economic loss. Though the beetles could be controlled using synthetic pesticides, indiscriminate use of pesticide in the field causes problems such as pest resistance, environmental and health hazards etc. These pave way for the development of effective ecofriendly pest control measures. Plant based essential oils are used against these insect pests, as they constitute a rich source of bioactive components and reported to have many biological properties. Recently, essential oils were formulated as nanoemulsion and was developed for their effectiveness and eco-friendly nature. In this study, the oil in water (O/W) nanoemulsion of Mentha piperita were prepared by ultrasonication method at different concentrations and examined for the stability study. The stable nanoemulsion was characterized by DLS and was reported to consist with 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 bulkemulsion, it was screened against the adult beetles, Henosepilachna vigintioctopunctata at different concentrations for 96 hours and the resulted LC₅₀ value of nanoemulsion was 15.84 % which was found to be very effective than the LC₅₀ value of bulkemulsion, 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.