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 New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>