Bioactive Cinnamon as an Eco-Friendly Botanical Insecticide: Toxicity Against the Brown Planthopper (Nilaparvata lugens)

Abstract

The brown planthopper (Nilaparvata lugens) is a destructive rice pest, while the extensive use of synthetic insecticides has raised concerns regarding environmental pollution and insect resistance. This study evaluated the potential of cinnamon (Cinnamomum sp.) essential oil as a botanical insecticide through chemical characterization, emulsion formulation, and toxicity assessment against N. lugens. The cinnamon oil was characterized by GC-MS and formulated into an oil-in-water (O/W) emulsion with Tween 80 and ethanol. Insecticidal activity was evaluated by contact bioassays on second-instar nymphs. GC–MS analysis identified cinnamaldehyde (84.78%) and cinnamyl acetate (10.05%) as the major constituents. The emulsion exhibited good homogeneity, physical stability, and acceptable pH throughout storage. Mortality increased with both concentration and exposure time, demonstrating a clear dose-dependent response. Probit analysis yielded LC50 and LC95 values of 168.32 and 1415.7 ppm in the preliminary assay, and 206.57 and 3691.3 ppm in the advanced assay. The highest concentration (1400 ppm) produced 86.67% mortality after 96 h. Although less effective than fipronil, cinnamon essential oil showed promising potential as an environmentally friendly botanical insecticide for sustainable management of brown planthopper populations.