Female mosquitoes have a powerful olfactory system—it helps them sniff out sweaty victims and potential mates. Their "odorant receptors," the special chemical sensors that detect smells, are found on their antenna. But, according to new research, male mosquitos—or at least their gametes—rely on this sense, as well. These same odorant receptors are also present on the insect's sperm.
The researchers were quite surprised at this discovery. They were originally clued in on the receptors' existence when they found molecules in males that are normally associated with females. Narrowing down the hunt for those receptors, they pinpointed them as occurring in the testes. While testing mosquito sperm's reaction to different chemicals, they found that the sperm began to excitedly flail about when it came into contact with certain chemical concotions. The sperm tails, it turned out, contained odorant receptors.
Female mosquitoes store sperm inside thier body, in a special container called the spermathecae, after mating. There, the sperm waits dormant until the females find a prerequisite blood meal for producing her eggs. The researchers think that the receptors on the sperm might chemically clue those cells in that it's time to kick into action, once all the pieces are in place for fertilization. "There are reports that within one day after insemination, the sperm begin swimming around in the spermathecae," the researchers said in a statement. "There must be one or more signals that activate this movement and our findings suggest that odorant receptors may be the sensor that receives these signals."
The team decided to take a look at a few other insect species, and found that both wasp and fruit fly sperm also carry their own odorant receptors. Given the essential role smell seems to play in ensuring the next generation of disease-carrying mosquitoes or insect pests comes into being, the researchers wonder if the sperm might hold a clue for controlling some of those populations.
Here, the researchers talk a bit more about their work: