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Research team discovers hormone that causes malaria mosquito to urinate
August 25, 2005Prior to coming to Nevada 16 years ago, David Schooley was a key figure at a small company in Palo Alto, Calif. that developed methoprene, an insecticide that halts the maturation of insect larvae to adults.
Methoprene, which has the same effect as an insect hormone called juvenile hormone, also stops the insect from reproducing. It is being used heavily throughout the United States to help prevent the spread of West Nile Virus.
Schooley's contribution to the development of methoprene was to prove that it is harmless to animals and the environment.
"Table salt is far more toxic," said Schooley, a professor of biochemistry at the University of Nevada, Reno's College of Agriculture, Biotechnology and Natural Resources
The problem with methoprene, however, is that for a species such as the tobacco hornworm, methoprene causes it to grow larger instead of transforming into a moth, enhancing the pest's ability to devastate crops.
"It's not a great way to sell an insecticide to a farmer," Schooley said. "Most money in pesticide development is in making insecticides for pests which attack crops."
This is what lead Schooley, and his colleague Geoff Coast of the University of London, down the path of finding a way to control insects that are pests at the larval stage, a path that has them instead potentially paving the way for better mosquito control.
A potential solution to the problem of killing insects at any stage of development may be found in peptide hormones, small proteins in all animals that regulate most bodily functions. While researching the genome of the malaria mosquito, Schooley discovered two different types of diuretic hormones similar to those from other insect species. These were synthesized at the University of Nevada, Reno then sent to London to study their effects on mosquitoes.
When a mosquito sucks blood from a human-and only pregnant female mosquitoes do this-it will take in twice its body weight in blood. To decrease this added weight, the mosquito urinates on its victim to release fluids.
Coast discovered that introducing one of the two diuretic hormones, DH31, into the mosquito causes the mosquito to excrete fluid rich in sodium chloride, the main salt in blood.
"Only DH31 causes the massive loss of sodium chloride which causes the mosquito to pee," Schooley said. "Stimulation of this process when the mosquito is not feeding could make the mosquito die."
Implications of this discovery, which is published in September's issue of the Journal of Experimental Biology, could lead to the development of a pesticide for controlling mosquitoes.
"Synthetic compounds that mimic the action of these peptide hormones should be useful as pesticides," Schooley said. "Like methoprene, DH31 only affects lower species such as insects, which suggests it should be very safe to non-insect species.\\\
University of Nevada
The problem with methoprene, however, is that for a species such as the tobacco hornworm, methoprene causes it to grow larger instead of transforming into a moth, enhancing the pest's ability to devastate crops.
"It's not a great way to sell an insecticide to a farmer," Schooley said. "Most money in pesticide development is in making insecticides for pests which attack crops."
This is what lead Schooley, and his colleague Geoff Coast of the University of London, down the path of finding a way to control insects that are pests at the larval stage, a path that has them instead potentially paving the way for better mosquito control.
A potential solution to the problem of killing insects at any stage of development may be found in peptide hormones, small proteins in all animals that regulate most bodily functions. While researching the genome of the malaria mosquito, Schooley discovered two different types of diuretic hormones similar to those from other insect species. These were synthesized at the University of Nevada, Reno then sent to London to study their effects on mosquitoes.
When a mosquito sucks blood from a human-and only pregnant female mosquitoes do this-it will take in twice its body weight in blood. To decrease this added weight, the mosquito urinates on its victim to release fluids.
Coast discovered that introducing one of the two diuretic hormones, DH31, into the mosquito causes the mosquito to excrete fluid rich in sodium chloride, the main salt in blood.
"Only DH31 causes the massive loss of sodium chloride which causes the mosquito to pee," Schooley said. "Stimulation of this process when the mosquito is not feeding could make the mosquito die."
Implications of this discovery, which is published in September's issue of the Journal of Experimental Biology, could lead to the development of a pesticide for controlling mosquitoes.
"Synthetic compounds that mimic the action of these peptide hormones should be useful as pesticides," Schooley said. "Like methoprene, DH31 only affects lower species such as insects, which suggests it should be very safe to non-insect species.\\\
University of Nevada
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Researchers at the California Institute of Technology (Caltech) and the University of California, San Diego (UCSD) have discovered that injecting a simple hormone into leeches creates a novel way to study how hormones and the nervous system work together to produce species-specific reproductive behavior.
Barrier in mosquito midgut protects invading pathogens
Scientists studying the Anopheles gambiae mosquito - the main vector of malaria - have found that when the mosquito takes a blood meal, that act triggers two enzymes to form a network of crisscrossing proteins around the ingested blood.
ARS study provides a better understanding of how mosquitoes find a host
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Experimental vaccine protects monkeys against chikungunya
Imagine a mosquito-borne virus that has already infected millions of people in recent outbreaks in South and Southeast Asia, the islands of the Indian Ocean, Africa and northern Italy.
Study: Climate change one factor in malaria spread
Climate change is one reason malaria is on the rise in some parts of the world, new research finds, but other factors such as migration and land-use changes are likely also at play.
Health care volunteers and disasters: First, be prepared
A surge in volunteers following a major disaster can overwhelm a response system, and without overall coordination, can actually make a situation worse instead of better.
Flightless mosquitoes developed to help control dengue fever
A new strain of mosquitoes in which females cannot fly may help curb the transmission of dengue fever, according to UC Irvine and British scientists.
Scientists transplant nose of mosquito, advance fight against malaria
Scientists at Vanderbilt and Yale universities have successfully transplanted most of the "nose" of the mosquito that spreads malaria into frog eggs and fruit flies and are employing these surrogates to combat the spread of the deadly and debilitating disease that afflicts 500 million people.
Bad news for mosquitoes: Yale study may lead to better traps, repellents
Yale University researchers have found more than two dozen scent receptors in malaria-transmitting mosquitoes that detect compounds in human sweat, a finding that may help scientists to develop new ways to combat a disease that kills 1 million people annually.
Scientists find ideal target for malaria therapy
Scientists at Washington University School of Medicine in St. Louis have identified a protein made by the malaria parasite that is essential to its ability to take over human red blood cells.
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