Wood Vinegar as an Alternative Insecticide in Controlling Rice Weevil, Sitophylus oryzae (Coleoptera: Curculionidae)

Abstract

Rice production faces many challenges including damages due to pest infestation in storage after harvest. Stored rice grains are often under threat and damage from pests such as rice weevil which resulted in reduction of the quality and quantity. Application of chemical insecticides helps to control this pest, however, it gives negative impacts to the environment and human health. Application of plant-based insecticides including the use of wood vinegar can become an alternative to the conventional method. This work describes the effectiveness of wood vinegar as bioinsecticide to inhibit the rice weevil’s activity by assessing the repellency, mortality and antifeedant activity at different concentration of 50, 100, 150 and 200 rpm. Wood vinegar showed high repellency of 98.3% towards rice weevils at 200 ppm after 5 hours of exposure times. Increased in concentration affects in increased mortality with highest number of 97% recorded at 200 ppm. The lethal concentration (LC) of wood vinegar was calculated to be 77.62 ppm. Antifeedant activity resulted in reduction of weight loss in stored rice with lowest reduction of 2% at 200 ppm. This promising result reflects the ability of wood vinegar as insecticidal agents in management and control of stored-grain pest.