Here's a head-scratcher: Human body lice (Pediculus humanus humanus) drink only human blood—but they may have no idea what it tastes like. The newly-sequenced louse genome, published online today in the Proceedings of the National Academy of Sciences, codes for only one-tenth as many taste and odor receptors as do the genomes of most other insects. It's still not clear which compounds the lice can taste and smell, but since there are so few, those receptors may be good targets for new pesticides or repellents. What's more, the louse relies entirely on a symbiotic bacterium, Reisia, to produce vitamin B5. The researchers behind the louse genome also sequenced the bacterium, and they found that it lacks genes for antibiotic resistance. So antibiotics might turn out to be louse killers, too.
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