Peppermint oil can keep mosquitoes away -- Study

Peppermint oil can keep mosquitoes away -- Study
PRESS TRUST OF INDIA

NEW DELHI, DECEMBER 5: Peppermint oil, the most popular essential oil used in perfumes, drugs, confectionery and flavours can be used to fight mosquitoes causing malaria, dengue and filariasis, according to a new study by researchers here.

Apart from keeping these mosquitoes at bar, the oil kills their larvae too, the study by a joint team of researchers of Malaria Research Centre (MRC) and Indian Institute of Technology (IIT) here says.

Published in the Elsevier Science Journal Bioresource Technology, the study says oil extracted from mentha peperital plant has strong repellent action against mosquitoes when applied on human skin and is particularly effective against "anopheles culicifacies" mosquito responsible for around three-quarters of malaria transmissions in North India.

The oil was found to be highly effective in killing three mosquito species anopheles stephensi (causes malaria), aede aegypti (spreads dengue fever) and culex quinquefasciatus (spreads filariasis and West Nile virus) M AAnsari, deputy director (entomology) at MRC, who led the study, said.

Protection offered by the oil varied from species to species, averaging 85 per cent. Sub-lethal doses of the oil in water containing larvae inhibited their growth, fecundity and fertility. Higher concentration could kill all the larvae, Ansari says.

Films of the oil were spread over trays of water carrying the larvae. Three millimetres of the oil in a square metre of water surface killed all the quinquefasciatus larvae, 90 per cent of the aegypti larvae and 85 per cent of the stephensi larvae within a day, the study found. Peppermint oil is as effective as mythol oil which is commercially used as a mosquito repellent and can be used in areas where stagnant water poses a grave problem.

About one millilitre of the non-toxic oil applied over exposed body parts can repel mosquitoes for up to ten hours. It is a viable substitute for chemical mosquito repellents available in the market which have harmful effects on human body, Ansarisays.

He says that the government should take appropriate measures to stop rise in the price of peppermint oil after the findings become popular. Currently, the oil sells at Rs 200-250 per litre. It should also make arrangements to manufacture and sell the oil at reasonable price through cooperatives. The finding will make malaria eradication efforts less expensive, as a major part of the funds is spent on insecticide to kill breeding larvae, he says.IIT's centre for rural development helped extract high-quality oil through steam distillation of mentha leaves. IIT was supported by Council of Scientific and Industrial Research (CSIR) and Department of Science and Technology (DST).

Other scientists involved in the project are MRC's R Krazdan and IIT's Padma Vasudevan and Mamta Tandon. Peppermint oil is a colourless pale yellow liquid with strong pungent odour similar to that of pepper. The mentha piperital plant is a native of the Mediterranean region, but is now grown all over the world. It is a perennialhairless mint (a group of plants belonging to the "labiateae" family) variety.

Menthol, a white crystalline compound used in medicine and flavours, is a prime component of this oil.