Abstract

The essential oils from the dried fruits of three common spices, Trachyspermum ammi,Anethum graveolens and Nigella sativa were isolated by hydrodistillation and its repellent, toxic and developmental inhibitory activities were determined against wheat flour insect pestTribolium castaneum. The three essential oils repelled the adults of T. castaneum at low concentrations in the filter paper repellency assay. The death of larvae and adults of T. castaneum was caused by fumigation with these essential oils. Median lethal concentrations (LC₅₀) of T. ammi, A. graveolens and N. sativa essential oils against larval stages of the insect were 11.62, 14.78 and 9.46 ml and against adults were 13.48, 16.66 and 10.87 ml, respectively. Median effective concentrations (EC₅₀) of T. ammi, A. graveolens and N. sativa essential oils that reduce to a half the transformation of larval population into pupa were 6.70, 7.86 and 5.62ml, respectively. These essential oils reduced the oviposition potential and increased the developmental period of the T. castaneum in comparison to the control group. Fumigation of these essential oils inhibited development of larvae to pupae and the pupae to adults and also resulted in the deformities in the different developmental stages of the insect. All the responses were found concentration-dependent.

Key words: Trachyspermum ammi, Anethum graveolens, Nigella sativa, Tribolium castaneum,  insecticidal   activity,  essential oils.