Researchers have isolated bioactive compounds from a specific bacterium that grows in soil-living worms1. The compounds prevent the feeding of mosquitoes that spread diseases such as dengue and malaria, making them potentially useful as mosquito repellents for reducing the burden of these diseases in Asia and Africa.
Some microbes, plants and animals secrete a chemically diverse group of organic compounds that have already been used to make antibiotics and other drugs. However, few studies have explored their mosquito-repelling potential.
An international research team, including a scientist from the ICMR-National Institute of Malaria Research in New Delhi, India, prepared a solution using a mixture of compounds isolated from the bacterium Xenorhabdus budapestensis . They then compared this solution’s efficiency in disrupting mosquito feeding with those of two synthetic insecticides: diethyl-3-methylbenzamide (also known as DEET) and picaridin.
Screening assays were developed using an artificial diet and soaking cotton cloths separately in a bacteria-derived compound-based solution, and DEET- and picaridin-based solutions.
All the soaked cotton cloths inhibited mosquito feeding. The feeding-deterrent activities of the bacterial compounds were comparable to, or higher than, the two synthetic insecticides.
A majority of mosquitoes landed on a cotton cloth soaked in a 50 per cent feeding-deterrence dose of bacteria-derived compounds. But, about half succeeded in feeding.
At a 90 per cent or higher dose, few mosquitoes landed and none fed.
The researchers say that future experiments can determine the efficacy and toxicological properties of the deterrent compounds for use in mosquito-repellent formulations for eventual testing on human skin.
1. Kajla, M. K. et al. Bacteria: a novel source for potent mosquito feeding-deterrents. Sci. Adv. 5 (2019) doi: 10.1126/sciadv.aau6141