Repellent potential of medicinal oils against Tribolium castaneum (Herbst) under laboratory conditions

Laboratory experiments were conducted to determine repellency of five local medicinal oils i.e., neem Azadirachta indica A. Juss., castor Ricinus communis L., rapeseed Brassica napus L., lettuce Lactuca sativa L. and chamomile Anthemis cotula L. against Tribolium castaneum Herbst, each applied at 0.1, 0.5- and 1.0-ml doses. A glass cylinder divided into A, B and C sections with one end close was used. Fifty grams of wheat flour was placed at A and C ends. Twenty freshly emerged T. castaneum was released at the center of cylinder (B). The data was recorded after one-, two- and three-days to count number of T. castaneum at A and C for calculating percentage repellency. All the oils showed repellent potential against T. castaneum as their repellency increased with dose and time exposure. After three days, 100% repellency of T. castaneum was recorded in 0.5- and 1.0-ml doses of neem oil, followed by 6.67+-3.33% repellency at 0.1 ml neem oil. After three days, the maximum repellency of T. castaneum in rapeseed, castor, chamomile, and lettuce was 86.67+-7.26, 76.67+-6.01, 76.67+-4.41, and 75.00+-7.64%, respectively, all recorded at 1.0 ml dose. Overall, neem oil exhibited significantly more repellency of T. castaneum, whereas castor, lettuce, rapeseed and chamomile were found non-significant with each other. Among doses, although highest repellency was recorded at 1.0 ml dose, but not significantly different from 0.5 ml dose of the individual oil. Therefore, 0.5 ml should be applied per 50 grams of wheat flour to get effective repellency of T. castaneum. Keywords: Beetle, Flour, Medicinal oils, Repellency