Evaluation of freshly prepared juice from garlic (Allium sativum L.) as a biopesticide against the maize weevil, Sitophilus zeamais (Motsch.) (Coleoptera: Curculionidae)

Freshly prepared garlic (Allium sativum L.) juice, containing the antimicrobial allicin, was evaluated as a possible grain pro-tectant against the maize weevil, Sitophilus zeamais (Motsch.). Each experiment was set out in Completely Randomized Design (CRD) with four replications, and there was a control treatment. Adult mortality and weight loss percentage were investigated. There was an observed increase in adult mortality following days of exposure in all treatments. Statistically significant (p < 0.05) reduced grain loss was also observed in all the treatments when compared with the control. The juice samples were freshly prepared from an indigenous Nigerian garlic cultivar (GUN) and a cultivar purchased from a supermarket in Germany (GAG). These garlic juice samples exhibited lethal effects causing at least 90% adult mortality in contact toxicity tests. The amount of allicin in GUN was 1.88 mg/ml according to High Pressure Liquids Chromatography (HPLC) analysis, while the amount of allicin in GAG was 3.50 mg/ml. This study highlights the potential of A. sativum containing allicin for biorational control of maize grains against S. zeamais infestation and damage.