Study of synergistic effect of combination of gamma radiation with carum copticum C.B. Clarke essential oil against trogoderma granarium everts contamination

In order to reduce the problems due to use of chemical insecticides it is required to apply safe and proper methods to control insect pest. In this work, the combination effect of gamma radiation and Carum copticum C.B. Clarke essential oil against Trogoderma granarium Everts larvae, which is known as the major pest in the stored products, was investigated. Experiments were carried out at 27±1ºC and 65±5% R.H. under the dark condition and three cases were represented. They are: 1) application of gamma radiation and essential oil simultaneausly, 2) irradiation followed by the essential oil, 3) the essential oil followed by the irradiation. The mortality was recorded 24h after the initial treatment. Doses among 700-1000 Gy of gamma radiation and 14.25, 20.88 and 35.97 μl of oil were used. The study showed that the combination of gamma radiation with C. copticum oil increased the larvae mortality compared with the control one, so that the combination of 900 and 1000 Gy with doses of essential oil (14.25, 20.88 and 35.97 μl) increased the mortality to 100% after 20 days, where as these gamma doses alone could control only 20% of larvae after 20 days. The best interaction was obtained when the fumigated larvae were exposed to the radiation. The results showed that irradiation and essential oils can be used as a successful control of the stored product pests.