Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Female moths use olfactory signals to choose the best egg-laying sites

03.06.2013
Small changes in the composition of green leaf volatiles induced by herbivory guide ovipositing female moths to unattacked plants.

Researchers at the Max Planck Institute for Chemical Ecology, Jena, Germany, discovered that the ability of Manduca sexta moths to recognize changes in the profile of volatile compounds released by plants being attacked by Manduca caterpillars allows them to lay their eggs on plants that are less likely to be attacked by insects and other predators, and to avoid competing against other caterpillars of the same species for resources.


Functional calcium imaging in the antennal lobes of a female Manduca sexta moth: Different activation patterns (red spots) can be observed depending on whether the moths respond to (Z)-3-hexenyl acetate or (E)-2-hexenyl acetate. The odor of a (Z)-3-isomer or a (Z)-3 / (E)-2 ratio in favor of a (Z)-3-isomer − according to the odor bouquet of an unattacked plant − guides ovipositing Manduca females to plants that have yet been spared by herbivorous caterpillars. Copyright: A. Späthe / MPI for Chemical Ecology


Manduca sexta moth
Copyright: L. Kübler / MPI for Chemical Ecology

The results of field experiments and neurobiological studies were now published in the open access online journal eLIFE. (eLIFE, May 14, 2013, DOI: 10.7554/elife.00421)

“Green” leaf odors

Plants have developed many different strategies to defend themselves against herbivorous animals, particularly insects. In addition to mechanical defenses such as thorns and spines, plants also produce compounds that keep insects and other herbivores at bay by acting as repellents or toxins. Some of these metabolites are produced on a continuous basis by plants, whereas others – notably compounds called green-leaf volatiles – are mainly produced once the plant has been wounded or attacked. Green-leaf volatiles – which are also responsible for the smell of freshly cut grass – have been observed to provide plants with both direct protection, by inhibiting or repelling herbivores, and indirect protection, by attracting predators of the herbivores themselves.

Attracting the enemies of the herbivores

The hawkmoth Manduca sexta lays its eggs on various plants, including tobacco and Sacred Datura plants (Datura wrightii). Once the eggs have hatched into caterpillars, they start eating the leaves of their host plant, and if present in large numbers, these caterpillars can quickly defoliate and destroy the plant. In an effort to defend itself, the host plant releases green-leaf volatiles to attract various species of Geocoris, predatory bugs that eat insect eggs and tiny larvae.
One of these green-leaf volatiles released by tobacco plants is known as (Z)-3-hexenyl acetate, but enzymes released by M. sexta caterpillars’ spit change some of these molecules into (E)-2-hexenyl acetate, which has the same chemical composition but a different structure. The resulting changes in the volatile profile alerts Geocoris bugs to the presence of M. sexta caterpillars on the plant − their potential prey.

Ideal conditions for Manduca offspring

Now the scientists from the Max Planck Institute for Chemical Ecology show another interesting effect of the chemical “odor conversion”: Just like Geocoris bugs, adult female M. sexta moths are able to detect the changes in the green volatile profile emitted by Sacred Datura plants that have been damaged by M. sexta caterpillars. This alerts the moths to the fact that Geocoris bugs are likely to predate eggs and caterpillars on the plant, and as a consequence the moths lay their eggs on unattacked plants. Hereby they minimize the risk of newly laid eggs being eaten by the predators. Another positive effect is that the competition for resources with larvae that already feed on a plant is reduced.
Interdisciplinary Research: Ecology and Neurobiology

The researchers also identified the neural mechanism that allows moths to detect the slightest changes in the volatile profile of plants that have already been attacked by caterpillars. Neurobiological studies of the moth brain revealed that E- and Z- odors lead to different activation patterns. The two isomers of hexenyl acetate activated different regions in the antennal lobe of the moth (see images above). “This suggests that the female moths have isomer-specific receptors and neurons on their antennae,” says Bill Hansson, director of the institute. The combination of such neurological experiments and ecological field studies are very promising and may provide further insights into odor-guided behavior of insects in nature and agriculture.
New plant protection strategies

A similar behavioral pattern is known from potato beetles (Leptinotarsa decemlineata). An artificial application of (Z)-3- or (E)-2-hexenol, (E)-2-hexanal or 1-hexanol to potato plants lead to a disoriented behavior observed in egg-laying potato beetles. On the basis of these results, plant protection strategies seem possible which utilize artificial odor application in order to deter ovipositing insects from field crops and thereby reduce insect infestation. [McLennan /AO/JWK]

Original Publication:

Allmann, S., Späthe, A., Bisch-Knaden, S., Kallenbach, M., Reinecke, A., Sachse, S., Baldwin, I. T., Hansson, B.S. (2013). Feeding-induced rearrangement of green leaf volatiles reduces moth oviposition. eLife 2:e00421. DOI: 10.7554/eLife.00421

http://dx.doi.org/10.7554/eLife.00421

Further Information
Prof. Dr. Ian T. Baldwin, +49 3641 57-1101, baldwin@ice.mpg.de
Prof. Dr. Bill S. Hansson, +49 3641 57-1401, hansson@ice.mpg.de

Angela Overmeyer | Max-Planck-Institut
Further information:
http://www.ice.mpg.de/ext/1029.html?&L=0

More articles from Life Sciences:

nachricht Helping to Transport Proteins Inside the Cell
21.11.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht UNH researchers create a more effective hydrogel for healing wounds
21.11.2018 | University of New Hampshire

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First diode for magnetic fields

Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.

Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Helping to Transport Proteins Inside the Cell

21.11.2018 | Life Sciences

Meta-surface corrects for chromatic aberrations across all kinds of lenses

21.11.2018 | Power and Electrical Engineering

Removing toxic mercury from contaminated water

21.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>