Insecticidal Properties ofZingiber officinaleandPiper cubebaEssential Oils AgainstTribolium castaneumHerbst (Coleoptera: Tenebrionidae)

The essential oils from the rhizomes of Zingiber officinale (Zingiberaceae) and berries of Piper cubeba (Piperaceae) were isolated by hydrodistillation and its repellent, toxic and developmental inhibitory activities were determined against wheat flour insect pest Tribolium castaneum. In the filter paper repellency assay, Z. officinale and P. cubeba essential oils repelled the adults of T. castaneum significantly even at 0.00625% and 0.003215% concentrations (v/v) respectively. Fumigation of larvae and adults of T. castaneum with these two essential oils caused mortality. Median lethal concentrations (LC50) of Z. officinale and P. cubeba essential oils against larvae were 2.29 and 3.15µl/cm3 and against adults were 1.23 and 0.97µl/cm3 respectively. Fumigation with sublethal concentrations viz. 40 and 80% of 24-h LC50 of these essential oils significantly reduced the oviposition potential of the adults and inhibited development of larvae to pupae and the pupae to adults. All the responses were found concentration-dependent.