Showing posts with label mosquito repellent. Show all posts
Showing posts with label mosquito repellent. Show all posts

Wednesday, 18 May 2011

MALARIA: New Insect Repellent is 'Thousands of Times' More Effective Than DEET

May 11, 2011
Stagnant water and trash are breeding grounds for mosquitoes. Getty Images:
Stagnant water and trash are breeding grounds for mosquitoes.

Researchers at Vanderbilt looking for better ways to control the spread of malaria have stumbled across an insect repellent that is thousands of times stronger than DEET.
But it doesn't just work to confuse malaria-carrying mosquitoes. This new compound works against all insects, including flies, ants, and moths.
The compound known as VUAA1 was borne of recent discoveries about the fundamental way that mosquitoes smell. Just a few years ago, it was thought that the basic sniffing mechanism for mosquitoes was very similar to that of mammals -- that is, that odorant receptors (ORs) sitting atop nerve cells are tuned to different molecules, and when a receptor comes in contact with its target molecule it notifies the brain via the nerve.
But mosquitoes' olfactory senses works a bit differently. It turns out their ORs rely on a sort of nerve switchboard, a co-receptor called Orco.
When an OR detects an odorant molecule, it activates while the other ORs on a given antenna remain deactivated. The Orco acts as a sort of switch that tells the brain which OR is activated, and thus what molecule is being detected.
VUAA1 is basically a molecule that triggers the Orco directly rather than the ORs seperately. Like a sort of universal signal, it stimulates all OR-Orco connections, essentially simulating the effect of all the different receptors on an antenna firing at once.
For the mosquito, this creates sensory overload, like tasting something that tastes like every possible flavor at once.
In the presence of VUAA1, mosquitoes basically can't smell anything, which confounds their ability to sniff out blood or anything else.
Now the obvious question is: what else does VUAA1 do? The Vanderbilt team is working to better characterize the compound and to strip away any parts of it that don't contribute to its effectiveness. They will then start testing it for toxicity and other attributes that might have negative impacts on people or the environment.
The good news is that even if there doesn't happen to be a safe commercial application for VUAA1, the science is still there. Having found this unique means to overwhelm the common mosquito could lead to better future repellents that keep mosquitoes and other pests at bay (without being deadly/toxic) -- be it in malaria-prone regions of the world, in agricultural settings, or simply in the backyard.
http://www.foxnews.com/scitech/2011/05/10/new-insect-repellent-thousands-times-effective-deet/#ixzz1M6CaOLoB

Tuesday, 7 September 2010

MALARIA: 'Exciting' new odour sensors found in malaria mosquitoes

María Elena Hurtado
3 September 2010

An array of new mosquito repellents and lures may be possible following the discovery by researchers of a new set of sensors that the principal species of malaria-carrying mosquito uses to sniff out its targets.
Until now, research has focused on a family of odour receptors found in the antennae and other head appendages of Anopheles gambiae, the main carrier of the malaria parasite.
Work by researchers at Vanderbilt University in the United States, published in PLoS Biology last month (August), confirmed that this set of receptors is sensitive to DEET, the most commonly used repellent, and to a large number of other scents.
These receptors do not detect other important odours released by people, such as ammonia, butylamine and lactic acid. The researchers discovered a new set of receptors can detect these smells. Mike Lehane, head of the vector group at Liverpool School of Tropical Medicine in the United Kingdom, described the research as "highly skilful and exciting".
Fredros Okumu, a researcher at the Ifakara Health Institute, Tanzania, and the London School of Hygiene and Tropical Medicine, said the findings "open up even greater possibilities to screen for more compounds that could be used to compose blends of synthetic human odours that are super-attractive to human-biting mosquitoes".
The next step is to develop substances that these new receptors — known as ionotropic receptors — will respond to.
Laurence Zwiebel, senior author of the study, told SciDev.Net his team is already working on novel compounds that can both attract and repel mosquitoes. "We expect to bring these tools online in the next five to ten years," he said.
These substances could be used to lure mosquitoes to traps.
Traps are being investigated to clear tsetse flies that transmit sleeping sickness and are in use to control biting mosquitoes around salt marshes in the United States.
"An efficient push-pull approach – repelling and attracting/trapping – to malaria vector control would be particularly useful in countries where mosquitoes bite outside the home, as in parts of Asia," Lehane told SciDev.Net.
"Given the good results of indoor methods for malaria control such as insecticidal nets and spraying, traps fitted with synthetic odours should especially target outdoor transmission," Okumu agreed.
"Once we have enticing lures we will need to find the best places to locate the traps and, perhaps more importantly, ensure that they at least match the cost of existing interventions," he said.

http://www.scidev.net/en/news/-exciting-new-odour-sensors-found-in-malaria-mosquitoes.html

Saturday, 21 August 2010

MALARIA: Arm-in-cage testing of natural human-derived mosquito repellents

20 August 2010
Background
Individual human subjects are differentially attractive to mosquitoes and other biting insects. Previous investigations have demonstrated that this can be attributed partly to enhanced production of natural repellent chemicals by those individuals that attract few mosquitoes in the laboratory. The most important compounds in this respect include three aldehydes, octanal, nonanal and decanal, and two ketones, 6-methyl-5-hepten-2-one and geranylacetone [(E)-6,10-dimethylundeca-5,9-dien-2-one]. In olfactometer trials, these compounds interfered with attraction of mosquitoes to a host and consequently show promise as novel mosquito repellents.
Methods
To test whether these chemicals could provide protection against mosquitoes, laboratory repellency trials were carried out to test the chemicals individually at different concentrations and in different mixtures and ratios with three major disease vectors: Anopheles gambiae, Culex quinquefasciatus and Aedes aegypti.
Results
Up to 100% repellency was achieved depending on the type of repellent compound tested, the concentration and the relative composition of the mixture. The greatest effect was observed by mixing together two compounds, 6-methyl-5-hepten-2-one and geranylacetone in a 1:1 ratio. This mixture exceeded the repellency of DEET when presented at low concentrations. The repellent effect of this mixture was maintained over several hours. Altering the ratio of these compounds significantly affected the behavioural response of the mosquitoes, providing evidence for the ability of mosquitoes to detect and respond to specific mixtures and ratios of natural repellent compounds that are associated with host location.
Conclusion
The optimum mixture of 6-methyl-5-hepten-2-one and geranylacetone was a 1:1 ratio and this provided the most effective protection against all species of mosquito tested. With further improvements in formulation, selected blends of these compounds have the potential to be exploited and developed as human-derived novel repellents for personal protection.
http://www.malariajournal.com/content/9/1/239