Scientists can spend years working on problems that at first may seem esoteric and rather pointless. For example, there's a scientist in Arizona who's trying to find a way to measure the age of wild mosquitoes.
As weird as that sounds, the work is important for what it will tell scientists about the natural history of mosquitoes. It also could have major implications for human health.
Here's why. There's a nasty disease called dengue that is just beginning to show up in the United States. It's caused by a virus, and it's transmitted from person to person by a mosquito. A mild case of dengue is no worse than flu. A serious case can mean death.
Michael Riehle at the University of Arizona is trying to solve a curious puzzle about dengue: why there have been dozens of cases in nearby Texas and none, or virtually none, in Arizona. Riehle thinks the answer has to do with Arizona's geography.
"It's right on the edge of the range where these dengue mosquitoes are found," he says. "It's a fairly harsh environment, and we think that they might not be surviving long enough to efficiently transfer the disease to other people."
So to test his hypothesis, Riehle wants to be able to compare the life spans of mosquitoes in Arizona with those in Texas.
It's not easy to tell how old a mosquito is: It's not as if they carry around birth certificates or government-issued IDs. Right now the tools for measuring the age of mosquitoes are pretty crude. For example, you can look at a female mosquito's ovaries to see if they have produced any eggs. Riehle says if they have, that means the mosquito is at least five days old, since they can't produce eggs before that. "But that's all it can tell us — less than five days, or more than five days," Riehle says.
So Riehle has a new idea. He wants to see if he can use a mosquito's gene to tell its age.
Looking For Clues In Genes
There are ways to tell when a particular gene is switched on or off in a mosquito. Riehle is looking for genes that switch on or off when the mosquito reaches a particular age. He's found one so far. He needs more in order to make more age estimates.
