Cinnamon oil extract may control the spread of malaria.

Cinnamon oil extract may control the spread of malaria.

As well as being a general nuisance, various species of mosquito are carriers for major diseases, including dengue fever, West Nile virus and, most notoriously, malaria.

Effective control of mosquito populations is therefore an essential public health strategy in tropical countries. Organophosphate insecticides and insect growth regulators are currently the favoured means of control, but their widespread use can prove harmful to humans. What is needed is a natural and safe form of mosquito control, and this is what a team of Taiwanese researchers has now discovered in cinnamon oil.

There are around 250 species of tree in the genus Cinnamomum and they are found throughout Asia and Australia. The oil derived from many Cinnamomum species possesses a range of antibacterial, antifungal and insecticidal properties, prompting researchers from the National Taiwan University, Taipei, and Chang Gung University, Tao-Yuan, to wonder whether this oil could provide natural mosquito control.

Using gas chromatography and mass spectrometry, the researchers analysed essential oils derived from the leaves of eight different trees of the species Cinnamomum osmophloeum found throughout Taiwan. They detected 54 different compounds in the eight oils and found that oils from different trees could differ greatly in their chemical content.

The researchers tested the oils for their ability to kill mosquito larvae and found that oils from two of the trees were the most effective. Within the oils they discovered that four - cinnamaldehyde, cinnamyl acetate, eugenol and anethole - were more effective at killing mosquito larvae than the synthetic insecticide DEET.

The team has only tested these compounds on mosquito larvae, but team leader Shang-Tzen Chang explained: ’We think that cinnamon oil might affect adult mosquitoes by acting as a repellant’.

Jon Evans