Insecticidal fumigant action of mustard essential oil against Sitophilus zeamais in maize grains.

Abstract: This study was done to evaluate the fumigant toxicity of synthetic mustard essential oil (SMEO) (90% allyl isothiocyanate) on the developmental stages of the maize weevil (Sitophilus zeamais) and its effect on maize grain quality. Time-response bioassays were carried out in maize grains infested with eggs, 3rd instar larvae, pupae, or adults of the pest, using SMEO to provide allyl isothiocyanate (AITC) concentrations of 1.25 or 1.87 μl l⁻¹, for 60 h with assessment after an interval of 6 h or until 100% mortality was reached. The vapors of SMEO caused mortality of all stages of S. zeamais. However, eggs were significantly more tolerant than the other developmental stages, followed by pupae. The larvae were least tolerant. The moisture content, electric conductivity and germination of the grains was not affected by exposure to SMEO. This exploratory study shows that SMEO can be a good candidate for development as an eco-friendly grain fumigant for weevil control. [Copyright &y& Elsevier]