Potential of eucalyptus oil as repellent against house rat, Rattus rattus.

Rodent repellents are chemicals which by taste or odour or possibly by both will prevent animal from feeding or gnawing. Such substances may be used in protecting an area from rodent infestation or in protecting packaged food, packing materials, electric cables, and other important vulnerable materials. Mature and healthy house rat, Rattus rattus of both sexes, was exposed to 5, 10, and 20% eucalyptus oil applied as spray in laboratory pens in bichoice tests. Each concentration was applied through three different modes of application, that is, daily, once, and alternatively in a week. Repellent effect of the oil was assessed based on food consumption from treated and untreated sides for four days. In overall, food consumption was significantly (P < 0.0001) low from treatment side compared to the untreated side indicating significant repellent effect of the oil at all the three concentrations tested. Repellent effect of the oil was, however, not found to differ significantly between the two sexes. Percent repellency in both male and female rats was apparently more with daily application of 5 and 10% eucalyptus oil. Present studies reveal the potential of eucalyptus oil in repelling away R. rattus; however, further studies may be conducted to enhance the persistence of repellent effect for longer period of time.