Pantnagar Journal of Research

Abstract

The experiments were conducted to study the long-term efficacy of essential oils of Curcuma longa and Pinus roxburghii at 0.2 and 0.4 per cent along with their combinations at 0.2+0.2 and 0.1 +0.1per cent each against three major insect pests of stored grains, Sitophilus oryzae, Rhyzopertha dominica and Tribolium castaneum. The wheat grain artificially infested by these insects were fumigated by abovementioned formulations on 5th, 10th, 15th and 20th days of infestation. The observations on population buildup of test insects were recorded after6- and 8-monthsstorage while percent infestation and per cent weight loss of grain was recorded after 10 months storage. The study revealed that the herbal fumigants having essential oil of C. longa or P. roxburghii oil at 0.4 per cent or C. longa + P. roxburghii at 0.2 per cent each or P. roxburghii at 0.2 per cent were highly effective against S. oryzae because no adults emerged from these treatments even when grains were fumigated on 20th days of artificial infestation by this insect. On the other hand, all the herbal fumigants were highly effective against R. dominica for more than 8 months when they were used for fumigation on 5, 10, 15 and 20 days of artificial infestation. In case of T. castaneum, C. longa oil was not very effective at 0.2-0.4 per cent against this insect. However, the combinations of C. longa+ P. roxburghii completely checked the progeny production for more than 8 months at 0.1+0.1 and 0.2+0.2per cent. The study revealed that the herbal fumigant having essential oil of C. longa and P. roxburghii in equal proportion is highly effective against all three major insect pests of stored cereals at lowest dose of 0.2 percent. Due to very high efficacy for 10 months and low cost of treatment, it may be used for protection of cereal grain or seed stored in airtight containers