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 Closing the carbon loop
08.12.2016 | University of Pittsburgh

nachricht Newly discovered bacteria-binding protein in the intestine
08.12.2016 | University of Gothenburg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Closing the carbon loop

08.12.2016 | Life Sciences

Applicability of dynamic facilitation theory to binary hard disk systems

08.12.2016 | Physics and Astronomy

Scientists track chemical and structural evolution of catalytic nanoparticles in 3-D

08.12.2016 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>