Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scent guides hawk moths to the best-fitting flowers

19.05.2016

Max Planck researchers show that Manduca sexta moths acquired the highest energy gain when they visited flowers that matched the length of their proboscis. The moths were supported in their choice of the best-fitting nectar sources by an innate preference for the scent of matching flowers.

That the morphology of many pollinators corresponds strikingly to the shape of the flowers they pollinate was observed more than 150 years ago by Charles Darwin. He described this perfect mutual adaptation of flowers and pollinators as the result of a co-evolutionary process.


A hawk moth (Manduca sexta) uses its eight-centimeter-long proboscis to drink nectar from a flower of Nicotiana alata.

Anna Schroll


Bilder zur Pressemeldung Geruch führt Tabakschwärmer zur besten Blüte Alexander Haverkamp with a Manduca sexta hawk moth.

Anna Schroll

Scientists at the Max Planck Institute for Chemical Ecology in Jena, Germany, have now provided further proof of the famous naturalist’s theory. They were able to show that Manduca sexta moths acquired the highest energy gain when they visited flowers that matched the length of their proboscis.

The moths were supported in their choice of the best-fitting nectar sources by an innate preference for the scent of matching flowers. The results of this study have been published in the journal Nature Communications (Nature Communications, May 2016, doi: 10.1038/NCOMMS11644).

Flower-pollinator systems as a result of mutual adaptation

Charles Darwin, the founder of the theory of evolution, was an astute observer of nature. His extraordinary understanding of natural history laid the foundation of his theory about the origin of species. In 1862, he published a book about orchids and their pollinators in which he described the orchid Angraecum sesquipedale, which was cultivated in England but originated from Madagascar.

Because of the flower’s morphology, Darwin hypothesized that there must be a pollinator in the plant’s native habitat with an extraordinarily long proboscis enabling the nectar in the flower to be reached. In 1903, more than 20 years after Darwin’s death, such a pollinator was in fact discovered: the hawk moth Xanthopan morganii, which received the subspecies name praedicta (the predicted) in honor of Darwin’s hypothesis. This moth has a proboscis which is more than 22 centimeters long.

Biologists use the term “pollination syndrome” when they explain the amazing diversity of flowering plants and pollinators which has emerged as a result of co-evolution. A flower-pollinator system can be highly specialized. Both partners benefit from the relationship: The plant increases the likelihood it will transfer pollen to flowers of conspecifics and not waste it on other species. Specialized pollinators, on the other hand, have an advantage over competing generalist pollinators, which are also foraging for nectar, because their proboscis is better adapted. The disadvantages of such specialization are that the reproductive success of the highly specialized plant wanes when its pollinator is absent, and the survival rate of the pollinator decreases in the absence of the plant as well.

Darwin’s observations inspired Markus Knaden, who heads the studies with Manduca sexta hawk moths in the Department of Evolutionary Neuroethology, and his colleagues. They hypothesized that there must be a flower which fits this pollinator perfectly, although the moth is a generalist and visits a broad range of flowering plants. The tobacco hawk moths are larger than usual moths; when they hover in front of a flower in order to drink nectar they must beat their wings more than 30 times a second, an activity which looks exhausting and requires a lot of energy. The high energy loss makes the right selection of flowers extremely important: the moths cannot afford to waste energy on flowers whose nectar they cannot reach.

Energy balance after visiting a flower

In order to test their hypothesis, the scientists first developed a small wind tunnel which they used to determine the energy loss of moths during the flight. The loss was determined by measuring the carbon dioxide the moths were breathing out. (The amount of carbon dioxide exhaled is directly related to the energy moths consume when foraging for nectar.) In addition, the researchers used gas-chromatographic and mass-spectrometric analyses to calculate the concentrations of single sugars in the nectar of the flower species used in the experiments and thus to determine each flower’s calorie content.

Altogether, seven tobacco species of the genus Nicotiana were tested. These Nicotiana flowers differed greatly in the lengths of their corollas; in centimeters, these ranged from less than 1.5 (Nicotiana rustica), to over 3 (Nicotiana attenuata), to 7.5 (Nicotiana alata) and to more than 11 (Nicotiana longiflora). “Although we had originally expected that the longer flowers which contain more nectar would also be more attractive in terms of energy gain, we found that essentially all flowers in our test provided the same amount of calories. While the longer flowers had more nectar, the nectar of shorter flowers was more concentrated. The nectar provided could not be the reason why visiting some flowers was more profitable than visiting others,” explains Alexander Haverkamp, a doctoral student who is the first author of the study.

From their measurements and calculations, the scientists were able to deduct the energy balance: the net-energy gain which resulted from balancing the energy gain per flower visit against the energy spent on hovering in front of a flower. Energy loss can be measured in the form of carbon dioxide, whereas energy gain is measured as the calories acquired from nectar uptake.

3-D tracking in the wind tunnel

Are moths able to assess the expected net-energy gain of a flower from a distance? To answer this question, the researchers designed a three-dimensional tracking system specially developed for the wind tunnels and consisting of multiple cameras which can record the movements of single moths. The flight of each moth was recorded in the dark for four minutes and then evaluated. For the first time, scientists were able to measure and visualize where in the wind tunnel odor molecules (here, the scents of the flowers) were present and at what concentrations. This new technology made it possible to correlate the presence of an odor with the behavior of a moth, especially when the moth first came into contact with this odor.

All moths in the experiments were encountering the scent of flowers for the first time; therefore, their responses to the odors and the preferences they revealed had to be innate. Hungry moths showed the strongest response to the flower of Nicotiana alata. The odor of this flower was especially attractive. Moths which encountered this odor plume immediately navigated towards it. Moreover, the moths were easily able to reach the nectar of these flowers with their probosces.

Therefore, only visits to N. alata flowers resulted in a positive net-energy gain. When visiting other Nicotiana flowers, hawk moths spent excessive amounts of energy, because they had difficulty drinking nectar from flower corollas which were too short or too long. “We showed that Darwin's prediction that each flower has a pollinator with a proboscis fitting into the flower, in Manduca not only resulted in a very long tongue, but also in a preference for the odor of the fitting flower. And that this co-evolution is beneficial for the moth, as the moth gets the best energy gain from fitting flowers,” Knaden concluded.

The pollination syndrome is important for the survival of many plants. In the course of evolution, mutual adaptations have resulted in the emergence of many species as well as in highly specialized flower-pollinator interactions. “Each pollinating species is important for the biological diversity on our planet. If one of the two partners becomes rare or extinct, this may have fatal consequences,” Haverkamp points out. Without pollinators, many flowers could no longer produce fruits. This would affect not only crop yield but the variety of food available for all humans. [AO]

Original Publication:
Haverkamp, A., Bing, J., Badeke, E., Hansson, B. S., Knaden, M. (2016). Innate olfactory preferences for flowers matching proboscis length ensure optimal energy gain in a hawkmoth. Nature Communications. DOI: 10.1038/NCOMMS11644
http://dx.doi.org/10.1038/NCOMMS11644

Further Information:
Dr. Markus Knaden, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße 8, 07745 Jena, Tel. +49 3641 57-1421, E-Mail mknaden@ice.mpg.de

Contact and Picture Requests:
Angela Overmeyer, M.A., Max Planck Institute for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, +49 3641 57-2110, E-Mail overmeyer@ice.mpg.de

Download of images and movies: http://www.ice.mpg.de/ext/downloads2016.html

Weitere Informationen:

http://www.ice.mpg.de/ext/1280.html?&L=0 Scent guides hawk moths to the best-fitting flowers
http://www.ice.mpg.de/ext/downloads2016.html?&L=0 Download of photos and videos
http://www.ice.mpg.de/ext/evolutionary-neuroethology.html Department of Evolutionary Neuroethology

Angela Overmeyer | Max-Planck-Institut für chemische Ökologie

Further reports about: Max-Planck-Institut carbon dioxide moths nectar pollinator wind tunnel Ökologie

More articles from Life Sciences:

nachricht Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington

nachricht The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

NASA Protects its super heroes from space weather

17.08.2017 | Physics and Astronomy

Spray-on electric rainbows: Making safer electrochromic inks

17.08.2017 | Materials Sciences

Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

17.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>