One thing that makes Aedes aegypti, the mosquito that spreads the dengue fever virus, such a huge problem for human health is its egg-laying habits.

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Chris Gash

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Females will deposit their eggs in just about anything that holds water, and many of these things are found in and around dwellings — flower pots and vases, used tires and discarded tin cans, to name just a few.

While the mosquitoes aren’t picky about the type of containers they use, they apparently are picky about the water, skipping over some sites in favor of others. Research has shown, for instance, that they are attracted to water that has leaves in it.

Now, scientists from North Carolina State University and Tulane University have identified some of the chemical cues in the water that determine where a mosquito will choose to lay its eggs. It’s not so much about the leaves, they report in The Proceedings of the National Academy of Sciences, but about the bacteria that come along with them.

Loganathan Ponnusamy, Ning Xu, Coby Schal, Charles S. Apperson and other researchers infused water with white oak and bamboo leaves and found that mosquitoes preferred these infusions over plain water.

Then they filtered all the bacteria out of the infusions and found that the filtered water attracted far fewer eggs, indicating that the cues that stimulate egg-laying are linked to the microbes.

Using several analytical techniques, the researchers were able to identify the specific stimulant compounds: fatty acids (a category of carboxylic acids) and methyl esters. Further tests showed that the concentrations of these compounds in the water was important as well — too high or too low and the female was likely to avoid the water.

The researchers say the findings could help public health officials devise more effective ways to attract and eradicate or otherwise control A. aegypti, and thus help stop the spread of dengue fever and other diseases.