Study of insecticidal properties of Trachyspermum ammi and Mentha arvensis essential oils against Sitophilus zeamais L. (Coleoptera: Curculionidae)

Trachyspermum ammi and Mentha arvensis essential oils have been evaluated for repellent, insecticidal and oviposition inhibitory activities in maize weevil, Sitophilus zeamais. In repellency assay, T. ammi and M. arvensis essential oils showed repellent activity against S. zeamais adults. These essential oils caused mortality in S. zeamais adults when applied by fumigation and contact methods. In fumigation toxicity assay, median lethal concentrations (LC₅₀) of T. ammi and M. arvensis essential oils were 0.385 and 0.323 μl/cm³, and 0.274 and 0.214 μl/cm³ air after 24 and 48 h exposure of S. zeamais adults respectively. In contact toxicity assay, median lethal concentrations (LC₅₀) of T. ammi and M. arvensis essential oils were found 0.317 and 0. 278 μl/cm², and 0.204 and 0.169 area after 24 and 48 h exposure of S. zeamais adults respectively. Essential oils of T. ammi and M. arvensis oils inhibited progeny production by inhibiting oviposition in S. zeamais adults when exposed to sub-lethal concentrations. This study concludes that T. ammi and M. arvensis oil can be used as alternative in management of stored-grain insects.