From Science News
January 16, 2019
Molecules made by bacteria keep mosquitoes at bay. The compounds are a newfound potential stand-in for DEET, a ubiquitous chemical used in most commercially available mosquito repellents in the United States.
In lab tests, the molecules were as effective as DEET in stopping Aedes aegypti mosquitos, which can carry Zika, dengue and yellow fever, from snacking on artificial blood, researchers report January 16 in Science Advances. Tests suggest the compounds also deter two other mosquito species: Anopheles gambiae, a major malaria carrier, and Culex pipiens, which can carry the West Nile virus.
Though DEET is considered safe for human use and effective against mosquitoes, it doesn’t hurt to have more lines of defense against the disease-transmitting insects, says coauthor Susan Paskewitz, an entomologist at the University of Wisconsin–Madison.
The molecules in question are metabolic by-products of Xenorhabdus budapestensis, a bacterium that has a symbiotic relationship with a species of soil nematode. When the nematode finds an insect host such as a caterpillar, it burrows in and defecates the bacteria into its host’s bloodstream. The bacteria weaken the host’s immune system and turn its insides to mush — a sort of “bacteria-insect milkshake” — which rapidly kills the host, says Adler Dillman, a nematologist at the University of California, Riverside who wasn’t part of the study.