Herbalists shed light on natural mosquito repellent
[CAPE TOWN] An alliance between traditional healers and scientists from South Africa's Council for Scientific and Industrial Research (CSIR) has led to the development of a mosquito-repelling candle due to go on sale early next year.
The candle was developed from a plant used for centuries by herbalists in the north-east of the country where malaria is rife. Branches of the aromatic plant have traditionally been hung in homes there to ward off mosquitoes.
"We work with the Traditional Healers Committee, which represents thousands of healers nationally who believe that science and technology can add value to indigenous knowledge," says Marthinus Horak, manager of the CSIR's bioprospecting programme.
By analysing chemicals released by the plant, the CSIR researchers identified the molecule that repels mosquitoes. They then distilled oils containing the repellent from the plant and mixed them into wax to create a candle that has the same properties as the leaves, but can be distributed more widely.
The project has taken 13 years to complete, partly because the scientists were unable to replicate their results and could not understand why. The traditional healers, however, knew the reason for the confusion — several related plants that look alike but do not have the same chemical properties.
"The traditional healers can tell the difference between the plants that [repel mosquitoes] and those that don't by the feel of the leaf and because they smell different," Horak told SciDev.Net.
While the traditional healers use their fingers and noses, Horak's team now relies on a laboratory technique called gas chromatography to identify the correct plant's unique chemical 'signature'.
An upsurge in malaria cases during the past ten years led locals to overharvest the plant, which made finding it in the wild difficult. In many regions only the identical but ineffective plants were found, so the team had to hunt for undisturbed land to find the right one.
"It is a very, very rare form," says Horak of the mosquito-repellent shrub. He adds, however, that it takes only one year before the plant is ready for harvest.
The researchers are keeping secret the identity of mosquito-repelling plant because of fears that others will attempt to collect specimens for commercial exploitation. Instead, the plant is being referred to as BP1, which stands for 'bioprospecting1'.
The healers' association will receive a proportion of the royalties and CSIR will receive income from licensing agreements with candle manufacturers.
Enquiries about the candle are coming in from as far as Canada and China, and CSIR's Vinesh Maharaj, who is responsible for commercialising the research, says his biggest worry is whether demand will outstrip supply.
Distilling oil from BP1
Maharaj is setting up a 30-hectare production site in the province of Limpopo where a community-based business will harvest the plant, distil the essential oils and manufacture the candles.
The factory will provide about 50 permanent jobs. Profits will go into community projects such as tarring roads or repairing clinics. Other planting sites are being established in the hot, dry interior of the Western Cape and in the plant's native Mpumalanga province.
Horak says the traditional healers have given CSIR more than 500 plant 'leads' as part of a broader collaboration between the two groups. About 30 are currently under investigation in the council's laboratories.