Posted on 09/02/2003 11:18:30 AM PDT by bedolido
Microscopic crablike creatures with a voracious appetite for swimming larvae may soon become the newest weapon in the war on mosquitoes.
A University of Florida researcher believes the tiny crustaceans have big potential for helping control buzzing hordes that have become a serious health threat with the spread of West Nile virus, malaria and other mosquito-borne diseases.
''They'll pretty much kill any mosquito larvae they see,'' said Jorge Rey, a professor at the University of Florida's Medical Entomology Laboratory in Vero Beach.
Rey hopes the organisms called copepods, common in Florida waters, will bolster the growing arsenal of what scientists call ''bio-controls'' -- insect killers without the environmentally unfriendly baggage of pesticides.
While South Floridians long ago learned to accept mosquito bites as inevitable in a water-ringed landscape, life this summer has grown edgier with a slow but steady rise in illnesses -- seven people with malaria in Palm Beach County, four hit with West Nile in Broward and one in Miami-Dade, along with infected animals and birds in all three counties. Statewide, at least 24 people have been hit by some mosquito-borne illness.
But even as medical cases and public concerns mount, mosquito-control agencies face a future of relying less and less on what has long been the most effective insect killer -- chemicals such as malathion, dibrom and naled.
''We certainly welcome any biological control they can develop for us,'' said Shelly Redovan, executive director of the Florida Mosquito Control Association. ``That's the direction that most people are leaning to.''
CHEMICALS' LIMITS
While chemical sprays and granules remain the chief weapon, particularly in Central and North Florida and for adult mosquitoes, they have limitations:
• In some cases, they can kill more than skeeters -- not just other bugs but birds and small animals.
Last October, environmental groups sued the U.S. Environmental Protection Agency to halt the use of fenthion, a mainstay in Southwest Florida, after it became the prime suspect in killing shorebirds on Marco Island in 1998 and 1999. This March, Bayer, the company that made it, wrote the EPA that it was halting production because sales weren't large enough to support the cost of additional environmental safety tests.
• Researchers are tracking a growing chemical resistance in some species, which can occur when generations of insects are exposed to the same pesticides.
• Environmental restrictions limit the use of some chemicals in sensitive marshes and coastal areas -- such as the Everglades, Florida Keys and mangroves lining much of Florida's coast.
• Large companies aren't developing new mosquito-specific pesticides, citing the high cost of development and environmental studies and the limited profit potential.
''Our market is really very small compared to agriculture,'' said Redovan. ``There isn't a financial reward for chemical companies to come up with them.''
From the old drain-and-spray-the-swamp days of decades ago, mosquito-control agencies have evolved to use -- as Redovan put it -- an increasingly large number of ``tools in the tool box.''
With 70-something species of mosquitoes growing in everything from salt marshes to flower pots, there is no one-shot solution, said Joseph Marhefka, Broward County's mosquito-control manager.
PESTICIDE SPRAYS
For full-grown flying bloodsuckers, pesticide spraying remains the biggest and best gun.
But it's more effective to kill mosquitoes before they hatch into adults. That's where bio-controls have shown the most promise. Many agencies have used one, a mosquito-eating fish called gambusia.
But bio-controls, like chemicals, also have limitations. For starters, they're labor-intensive, Marhefka said, which can make them expensive.
''You can put so many fish in a ditch and then the ditch dries up and you have to go back next time,'' he said.
There are other mainstream bio-controls as well. The most common is Bti, a soil-based bacteria used for more than a decade. Mosquito larvae eat it, then are eaten inside out by a protein that attacks their gut walls. But it works mainly on young and feeding larvae, not older pupa about to become adults.
While copepods aren't new controls -- they've been used in Vietnam and Australia -- Rey believes he's found one, Macrocyclops albidus, that could soon become an attractive alternative for Florida authorities.
90 PERCENT KILL RATE
In two years of testing, Rey found they attack larvae even when they're not in the mood to eat them. The kill rate reaches 90 percent.
They're cheap to raise in small pools or garbage cans, hardy enough to withstand short freezes, reproduce with rapidity that would make a rabbit blush and can survive in any pool of freshwater -- at least one without chlorine.
They're also native critters, found commonly in Florida waters and throughout the world, which should eliminate concerns of some new bug running amok in the environment, he said.
Rey believes the little things can be particularly well-suited to controlling populations in troublesome places such as dumps, where water collects in countless nooks and niches.
While he's still studying how they can be most efficiently dispersed -- they're small enough to be used in spray-guns with some modifications -- Rey plans to put out a paper on cultivating them within a month.
Rey certainly isn't alone in researching alternative mosquito treatments.
Hundreds of scientists at UF, other universities, government agencies and private companies are spending an estimated $100 million a year on studies examining everything from fungus to genetic manipulation. Earlier this year, scientists with the U.S. Department of Agriculture isolated a virus that in tests killed 95 percent of Culex mosquitoes, considered a prime West Nile spreader, after they added magnesium to the water.
PERSISTENT PESTS
But neither copepods nor a virus is likely to eradicate one of mankind's most persistent pests.
Johnathan Day, another UF scientist in Vero Beach, said ``people are constantly working and trying to get something new and better but there is no magic bullet.''
While the relentless battle against bugs has made huge strides since the 1960s in Florida, Day said, ``mosquitoes are remarkably resilient. All we can do is just keep plugging away.''
That's damn good information. I was taking garlic supplements twice a day until the end of July when I ran out. I haven't gotten around yet to restocking that item. But now that you mention it, I didn't start getting all that many bites until the last month. I'm going out tonight to get some more!
Let me know if you wish to be added or removed from this list.
My first thought, too. I'm even more skeptical when I see the guy making the following claim:
They're also native critters, found commonly in Florida waters and throughout the world, which should eliminate concerns of some new bug running amok in the environment, he said.
Given that their mosquito-larvae food is obviously so plentiful worldwide, why is it that these little critters don't do a better job of controlling mosquitoes already? Could it be that they eat other things, too? (Maybe beneficial things?)
I don't know that I'd be too quick to rely on this little scheme. Something tells me there's much less than meets the eye here, except perhaps the potential for unintended harm.
Yes, I am from the deep south. And your point is....?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.