Mosquito research in the press

Stelenes at Stelenes at
Tue Feb 22 11:05:55 EST 2000

With all the talk of mosquitos, I thought this article from the Internet 
newswires would be of interest:

Why Do Mosquitoes Love People?

                                                                Updated 1:51 
AM ET February 22, 2000

   WASHINGTON (AP) - Whether it's a summer evening stroll, a fishing trip or 
a picnic in the park, more than likely
   those whiny little devils - mosquitoes - are going to find you. 

   Agriculture Department scientists are trying to learn why. 

   Humans give off hundreds, maybe thousands, of natural scents that bugs 
find irresistible. 

   "So far, we have found more than 340 different chemical scents produced by 
human skin, and some of these attract
   mosquitoes," says Ulrich R. Bernier, a chemist with USDA's Agricultural 
Research Service. 

   "Scientists have known for years that lactic acid present on human skin is 
a mosquito attractant. So far, this is true for
   only a handful of species, one of which is the yellowfever mosquito, Aedes 
aegypti. Finding what attracts mosquitoes
   will ultimately help us find ways to control them," Bernier says in the 
February issue of Agricultural Research magazine.

   Bernier works at the ARS Center for Medical, Agricultural,and Veterinary 
Entomology's Mosquito and Fly Research
   Unit in Gainesville, Fla. There, he and his colleagues are testing 
individual scents and combinations for attractiveness to
   different mosquito species. 

   Mosquitoes are placed in one side of a cage divided by a screen. An 
attractant is pumped in to see if mosquitoes will
   come to the screen. 

   Bernier says it's difficult to find an attractant because it appears that 
multiple compounds are needed to attract

   Since 1997, Bernier has been combining different blends and screening them 
at different levels to see which blends
   draw mosquitoes best. A promising scent is later combined and tested in a 

   With some blends, he says, "We can get about 90 percent of the mosquitoes 
in the cage to come to the mixture. This
   is impressive considering my own arm and hand attract only about 70 
percent of them." 

   "We still don't have a perfect blend," Bernier notes. "But, we're a lot 
closer than we've ever been." Several promising
   blends, for which Bernier has filed a patent, are combinations of 
human-produced odors with and without lactic acid. 

   In 1968, Gainesville scientists discovered lactic acid is an attractant 
for the yellowfever mosquito. At that time, carbon
   dioxide (CO2) was also thought to be necessary to attract mosquitoes. 
Bernier says what might be the single most
   important discovery about these blends is they don't use CO2, unlike most 
other blends or attractants. All of the
   specific chemical combinations he's isolated for both the yellowfever 
mosquito and Anopheles albimanus, a tropical
   mosquito that spreads malaria, don't need the CO2. 

   ARS entomologist Daniel L. Kline found something else: mosquitoes love 
dirty socks. 

   "I wore the socks for 12 hours on three consecutive days. When I wasn't 
wearing the socks, I put them in a sealed
   plastic bag," Kline says. "I also found mosquitoes love Limburger cheese. 
Interestingly enough, the main ingredient in
   the cheese is a bacterium that can be found on the human foot." 

   Donald R. Barnard, leader of the Gainesville research unit, says, "We 
expect attractant-enhanced traps to eventually
   surpass pesticides in effectiveness. We hope to develop stand-alone traps 
that can be used by homeowners or
   livestock producers." 

   "One day we hope to develop systemic repellents that can be taken orally 
or devices that can be worn to neutralize
   the attractive effects of a person to a mosquito," he adds

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