RENO, Nev. - In a combination laboratory-office with beakers and petri dishes a Reno biochemist is searching for a way to make mosquitoes pee themselves to death.

By finding the key that would cause mosquitoes to meet their urinary demise by dehydration, University of Nevada, Reno professor David Schooley and his fellow researchers hope to end the thousands of deaths caused each year by mosquito-spread malaria and to halt the spread of West Nile virus.

Schooley came closer to realizing that goal five years ago when he discovered a diuretic hormone that causes a dramatic increase in how much mosquitoes urinate.

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"The reason we think this has a good chance of working is because, after a blood meal, a mosquito more than doubles its weight," Schooley said. "That means it has to get rid of an enormous amount of fluid after feeding. It's like a 747 with 1,000 people on board. It has to lighten the load in order to take off."

After a mosquito finishes its meal - only the female bites to feed the eggs she carries - it begins excreting salt and water from the blood it just ingested, he said.

"What we would hope is if we treat the mosquito . . . before it has its blood meal, it will dehydrate and die," he said.

In tests, the hormone, a calcitonin-like peptide, worked when applied directly to what works as the mosquito's kidney. The problem is the peptide doesn't penetrate the mosquito's body when sprayed on it.

So the challenge is finding something similar that can penetrate mosquitoes and reach their equivalent of kidneys.

"What I want to find is a simpler, smaller molecule than the C-T peptide with the same biological effect on the mosquito," Schooley said. Finding that key molecule to make mosquitoes vulnerable to a new pesticide could be 10 years away, he said.

He is being aided by Geoff Coast, a physiologist with Birkbeck College of the University of London. Coast studies the effects on mosquitoes of peptides Schooley synthesizes. They are co-principals in the research project, which is funded by a $927,000 grant from the National Institutes of Health.

The implications of their discovery appeared in September's issue of the Journal of Experimental Biology.

William Hawley, a malaria biologist with the Centers for Disease Control and Prevention, said most malaria specialists agree that it isn't feasible to eradicate mosquitoes, but the goal is to reduce their life span so they don't transmit the disease.

Hawley said mosquitoes begin life free of malaria, and it is not until they bite someone who has the disease that they become infected. However, even after biting an infected person, it takes 10 days for the parasite to complete its life cycle, at which time the mosquito begins transmitting the disease.

"What research like this does, if they can work out a delivery system, is reduce the life span of mosquitoes so they would be rendered incapable of transmitting malaria," Hawley said.