Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Lay your eggs here

09.07.2008
NC State scientists discover chemical cues that stimulate egg laying by pregnant mosquitoes

North Carolina State University scientists have figured out one reason why pregnant yellow fever mosquitoes (Aedes aegypti), one of the most important disease transmitters worldwide, choose to lay their eggs in certain outdoor water containers while eschewing others.

In a paper published in Proceedings of the National Academy of Sciences, the NC State researchers show that certain chemicals emanating from bacteria in water containers stimulate the female mosquitoes to lay their eggs. The female mosquitoes sense these chemical cues and decide that the water container is a preferable environment for their larvae to develop.

The findings could have implications for devising lures and traps that might help control yellow fever mosquito populations in equatorial locations around the globe, which would go a long way toward preventing important global diseases like dengue fever and yellow fever, say the study's lead authors, Dr. Charles Apperson and Dr. Coby Schal, professors of entomology at NC State. Postdoctoral researchers Dr. Loganathan Ponnusamy and Dr. Ning Xu and senior researcher Dr. Satoshi Nojima also co-authored the paper.

The study shows that yellow fever mosquitoes are particularly motivated to lay eggs in water containers that have just the right amounts of specific fatty acids associated with bacteria involved in the degradation of leaves and other organic matter in water. The chemicals associated with the microbial stew are far more stimulating to discerning female mosquitoes than plain water, for example, or filtered water in which the bacteria once lived.

The study used a combination of approaches, including one in which the NC State scientists presented female mosquitoes with different types of bacteria and bacterial extracts, and, in Schal's words, figured out "what turned the mosquitoes on" to lay their eggs.

"Some water-filled containers are rejected by the female mosquito," Apperson says. "If we filter the bacteria out, the mosquitoes want no part of the water container. But put the filtered bacteria back in the water container, and the mosquitoes will be stimulated to lay eggs."

Female mosquitoes are choosy when it comes to finding the proper egg-laying habitats. They do not normally lay all their eggs in one location, but instead exhibit a behavior called "skip-oviposition," distributing eggs in multiple water-filled containers.

Once the NC State scientists discerned the specific chemical compounds that stimulated increased egg-laying – a blend of fatty acids and methyl esters – they exposed the mosquitoes to varied concentrations of the chemical brew. High concentrations of the brew gave the mosquitoes pause, causing them to withhold their eggs. Lower concentrations were more convincing to mosquitoes than high concentrations, but still not as convincing as the proper amount – found to be only 10 nanograms in 30 milliliters of water.

Mosquito larvae depend on microbes in their new homes for growth and development, so it is important for mothers to be discerning when it comes to living arrangements for their young, the researchers say.

Now, the NC State scientists hope to use this choosiness against female mosquitoes. Stimulating females to lay eggs in water containers that have lethal chemicals or insect growth regulators could be another tool in the overall strategy kit to control mosquitoes – and dreaded diseases like dengue fever.

"We want to use the mosquito's egg-laying behavior against itself for control purposes," Apperson says.

The research was supported by a grant from the National Institutes of Health, the Blanton J. Whitmire Endowment and the W.M. Keck Center for Behavioral Biology.

"Identification of bacteria and bacteria-associated chemical cues that mediate oviposition site preferences by Aedes aegypti"
Authors: Loganathan Ponnusamy, Ning Xu, Satoshi Nojima, Coby Schal and Charles Apperson, North Carolina State University; Dawn M. Wesson, Tulane University

Published: July 7, 2008, in Proceedings of the National Academy of Sciences online

Abstract: The yellow fever mosquito, Aedes aegypti, the global vector of dengue and yellow fever, is inexorably linked to water-filled human-made containers for egg laying and production of progeny. Oviposition is stimulated by cues from water containers, but the nature and origin of these cues have not been elucidated. We showed that mosquito females directed most of their eggs to bamboo and white-oak leaf infusions and only a small fraction of the eggs were laid in plain water containers. In binary choice assays we demonstrated that microorganisms in leaf infusions produced oviposition-stimulating kairomones, and using a combination of bacterial culturing approaches, bioassay-guided fractionation of bacterial extracts, and chemical analyses, we now demonstrate that specific bacteria-associated carboxylic acids and methyl esters serve as potent oviposition stimulants for gravid Ae. aegypti. Elucidation of these compounds will serve not only to better understand the chemical basis of egg laying behavior of Ae. aegypti, but these kairomones will likely enhance the efficacy of surveillance and control programs of this disease vector of substantial global public health importance.

Tracey Peake | EurekAlert!
Further information:
http://www.ncsu.edu

Further reports about: Apperson Chemical bacteria concentrations fever mosquito

More articles from Life Sciences:

nachricht Topologische Quantenchemie
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

nachricht Topological Quantum Chemistry
21.07.2017 | Max-Planck-Institut für Chemische Physik fester Stoffe

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

Im Focus: On the way to a biological alternative

A bacterial enzyme enables reactions that open up alternatives to key industrial chemical processes

The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....

Im Focus: The 1 trillion tonne iceberg

Larsen C Ice Shelf rift finally breaks through

A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...

Im Focus: Laser-cooled ions contribute to better understanding of friction

Physics supports biology: Researchers from PTB have developed a model system to investigate friction phenomena with atomic precision

Friction: what you want from car brakes, otherwise rather a nuisance. In any case, it is useful to know as precisely as possible how friction phenomena arise –...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA looks to solar eclipse to help understand Earth's energy system

21.07.2017 | Earth Sciences

Stanford researchers develop a new type of soft, growing robot

21.07.2017 | Power and Electrical Engineering

Vortex photons from electrons in circular motion

21.07.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>