Efficiency of Acalypha wilkesiana (Muell Arg.) leaf oil extract applied as a biocide against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Abstract

The ethanolic oil extracts of Acalypha wilkesiana was assayed for its biotoxicity against the survival of Callosobruchus maculatus, immature stages, damage and seed weight-loss. The result was dosage and time of exposure dependent. The contact treatment revealed A. wilkesiana oil as an applicable biocide as it significantly (p < 0.05) affect the survival rate, suppressed oviposition and adult emergence of C. maculatus, hence reduced seed damage and weight-loss in grains below economic injury level. Contact treatment were the most toxic with LD50 values of 3.97 and 5.85 at 72 h, significantly lower (p < 0.05) than fumigant values 4.16 and 6.04, suggesting its isolation for future biocide study to establish the dose and mode of action for commercialization in crop protection.