Phys.org [phys.org]:
A trio of researchers at the University of Wisconsin has discovered that a common soil bacterium produces a chemical that is more effective in repelling mosquitoes than DEET.
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The researchers report that their study began with Xenorhabdus budapestensis, a type of bacteria that takes up residence in soil-dwelling nematodes. The nematodes actually use the bacteria to help them parasitize insects. The researchers wanted to learn more about how the bacteria help kill insects and, in the process, found that mosquitoes were quite averse to its presence.
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Further testing showed that the chemical was up to three times more repellent than DEET.
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The researchers note that their work is purely preliminary, they have no idea if the chemical would be safe for human use, or if it could be made in mass quantities.
Let's hope they can get it to market before summer.