Antifeedant Activity of Chitosan Encapsulated Acorus calamus Rhizome Oil Nanoparticles on Spodoptera litura

Abstract

This study evaluated the antifeedant activity of chitosan-encapsulated Acorus calamus rhizome oil nanoparticles against larvae of Spodoptera litura under laboratory conditions. A choice leaf-disc bioassay was conducted using six-day-old larvae fed on castor leaves. Three formulations of A. calamus rhizome oil-loaded chitosan nanoparticles, designated ACRO-CSNPs 1, ACRO-CSNPs 2, and ACRO-CSNPs 3, were tested at concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5%, with five replications. Treated and untreated halves of castor leaf discs were placed in Petri plates, and larval feeding was recorded after 24 and 48 hours. Antifeedant activity was calculated based on the leaf area consumed from treated and untreated portions. At 24 hours, ACRO-CSNPs 1 and ACRO-CSNPs 2 recorded 100% antifeedant activity at all tested concentrations, while ACRO-CSNPs 3 ranged from 86.01% at 0.1% to 100% at concentrations of 0.3% and above. At 48 hours, ACRO-CSNPs 1 maintained strong activity, with 97.33% antifeedant activity at 0.1% and 100% at higher concentrations. ACRO-CSNPs 2 and ACRO-CSNPs 3 showed concentration-dependent activity. The results indicate that chitosan encapsulation of A. calamus rhizome oil may improve its feeding deterrent effect against S. litura larvae.