Researchers identify compounds in sweetgrass to keep mosquitoes away

Researchers have claimed that they have identified the compounds in sweetgrass that repel mosquitoes.

Researchers at the University of Guelph and the University of Mississippi investigated the components of plants used in traditional therapies and found that in their search for new insect repellents, folk remedies have provided good leads.

Lead researcher Charles Cantrell said that sweetgrass gave off a sweet aroma that repels mosquitoes. Cantrell's team in collaboration with other researchers performed steam distillation on sweetgrass samples and evaluated its oil for the ability to deter mosquitoes from biting.

The researchers filled small vials with a red-coloured feeding solution that mimicked human blood and covered the vials with a thin membrane. They coated the membranes with different substances i.e. the sweetgrass oil, alternative sweetgrass extracts obtained without steam distillation, the gold-standard insect repellent.

The researchers observed what the insects did by counting how many mosquitoes went for a bite of each type of 'blood' vat. Further, the researchers purified the oil into 12 fractions and again checked their ability to ward off the bugs.

They found three fractions that repelled mosquitoes as well as the oil. Using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry, the researchers identified two chemicals in these active fractions that seemed to be responsible for putting off mosquitoes, which were phytol and coumarin.