Essential Oil of Terminalia chebula Fruits as a Repellent for the Indian Honeybee Apis florea

Plant-based repellent formulations for honeybees play an important role in the bee management. For this purpose, the essential oil of an Indian medicinal plant, Terminalia chebula, commonly known as Myrobalan, was isolated for the first time. Hitherto unknown chemical constituents of the essential oil were determined by GC/MS. The repellent activity of formulations of the essential oil, tested towards the Indian honeybee Apis florea, was found to be dose dependent. The repellency (DeltaR) increased with the concentration of essential oil in the formulations, reaching a maximum for the formulation containing 50 mg/ml of oil. A further increase in the oil concentration was found to reduce the DeltaR. The screening of formulations of the major essential-oil components identified indicated that formulations of furfural, 5-methylfurfural, tetradecanoic acid, palmitic acid, and oleic acid elicited no response in honeybees. In contrast, the formulations of phenylacetaldehyde were repellent, while those of ethyl cinnamate were attractant. These findings might be an asset for beekeepers to improve the bee management. Attractant formulations are effective to attract bees to the desired areas, thus improving the efficiency of pollination. Repellent formulations are used to repel honeybees, especially when toxic insecticides are sprayed on the fields.