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 Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

nachricht Chlamydia: How bacteria take over control
28.03.2017 | Julius-Maximilians-Universität Würzburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers create artificial materials atom-by-atom

28.03.2017 | Physics and Astronomy

Researchers show p300 protein may suppress leukemia in MDS patients

28.03.2017 | Health and Medicine

Asian dust providing key nutrients for California's giant sequoias

28.03.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>