How mosquitoes find a host

Last Updated: Wednesday, March 10, 2010 - 13:07

Washington: Agricultural Research Service (ARS) scientists have found how the potentially deadly yellow-fever-transmitting Aedes aegypti mosquito finds a host.

They have discovered that the mosquito detects the specific chemical structure of a compound called octenol as one way to find a mammalian host for a blood meal.

Scientists have long known that mosquitoes can detect octenol, but this latest finding explains in greater detail how Ae. Aegypti - and possibly other mosquito species - accomplish this.

ARS entomologists Joseph Dickens and Jonathan Bohbot have shown that Ae. aegypti taps into the "right-handed" and "left-handed" structural nature of octenol, which is emitted by people, cattle and other mammals.

This ability to detect the "handedness" of molecules has been shown in mammals, but the discovery is the first case of scientists finding out how it works in an insect, according to the researchers.

When they hunt for a blood meal, mosquitoes hone in on a variety of chemicals, including carbon dioxide, lactic acid, ammonia and octenol.

Octenol is one of many carbon-based compounds that have a molecular structure that can take on either a "right-handed" or "left-handed" form.

Each form is a mirror image of the other, and a form`s "handedness" is determined by how its molecular bonds are assembled.

The scientists used frog eggs to help them make their discovery. They injected RNA from Ae. aegypti into the frog eggs, allowing the egg membranes to mimic the mosquito`s ability to detect octenol.

Then they attached microelectrodes to the frog egg cell membranes, passed octenol over them and recorded the electrical signals stimulated by the odours.

They ran the tests using both the right- and left-handed forms of octenol. The scientists found heightened electrical activity when the membrane was exposed to the right-handed form, and weakened activity when it was exposed to the left-handed form.
There are many natural compounds that can take on either a right-handed or left-handed form. While the effects of those differences on many plants and animals remains a mystery, the research shows the effects of octenol`s dual structure on the yellow fever mosquito and adds to scientists`understanding of how mosquitoes sense the world around them.

According to Dickens, the study may also open the door to speedier development of better mosquito repellents and traps.

The findings have been published in PLoS ONE.

ANI



First Published: Wednesday, March 10, 2010 - 13:07

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