Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Captive Breeding for Thousands of Years Has Impaired Olfactory Functions in Silkmoths

21.11.2013
Domesticated silkmoths Bombyx mori have a much more limited perception of environmental odors compared to their wild relatives. The extremely sensitive olfactory detection of pheromones in males eager to mate, however, remains unaltered.

A new study on silkmoths revealed that the insects’ ability to perceive environmental odors has been reduced after about 5000 years of domestication by humans.


Bombyx mori (left) and Bombyx mandarina (right) females. The domesticated moth has lost its camouflage coloration as well as its ability to fly.

Markus Knaden, Max Planck Institute for Chemical Ecology


In the domesticated species the number of sensilla is considerably reduced (left) in comparison to its closely related wild ancestor (right).

Sonja Bisch-Knaden, Max Planck Institute for Chemical Ecology

Scientists from the Max Planck Institute for Chemical Ecology in Jena, Germany, and their colleagues from Japan compared olfactory functions in Bombyx mori and in their wild ancestors. Perception of the pheromone bombykol, however, remained highly sensitive in domesticated males. (Proc. R. Soc. B., November 20, 2013, DOI 10.1098/rspb.2013.2582)

Silk: A natural product for 5000 years

The silkmoth Bombyx mori, originally native to China, was domesticated about 5000 years ago. Its larvae, silkworms, enclose themselves in a cocoon when they enter the pupa phase. They spin their cocoon from one single silk thread, which is several hundred meters long. For silk production, the cocoon − together with the pupa inside − is boiled and the silk filament is then unraveled. Special breeding moths are kept for silk farming. After mating female moths lay several hundred eggs from which the new silkworms hatch.

In the 1950s Bombyx mori became a model organism in modern olfactory research. The sex pheromone bombykol, released by female silkmoths, was the first insect pheromone to be characterized chemically. Bombyx mori males’ are highly sensitive to even a few molecules of the female attractant, and the sensilla on their antennae are easily accessible for electrodes. This made them an ideal model system for electrophysiological measurements to analyze their olfactory functions. As early as 1956, olfactory receptor responses, so-called electroantennograms, were recorded on Bombyx mori.

Still responsive to pheromones, but not to environmental odors

Scientists from the Department of Evolutionary Neuroethology at the Max Planck Institute for Chemical Ecology and their collaborators from Japan have found that Bombyx mori is now considerably impaired in its olfactory functions due to 5000 years of captive breeding. The moth’s perception of environmental odors, which may lead it to its exclusive host plant, the mulberry tree, has been significantly reduced. This was demonstrated when their responses to odor stimulation were compared to those of the closely related wild species Bombyx mandarina. The scientists recorded electroantennograms of individuals of both species that were stimulated with different scents from leaves or flowers.

Morphological analysis revealed that the number of sensilla on the antennae of Bombyx mori females is considerably reduced compared to the abundant sensilla of Bombyx mandarina. In addition, the researchers measured different activity patterns in the brain of the domesticated and the wild silkmoths by using calcium imaging techniques. These patterns were highly variable among individuals of domesticated silkmoths but were largely constant in their wild ancestor group as well as in four other insect species.

Compared to wild moths, domesticated silkmoths seem to have less ability to smell environmental odors with their antennae and to locate host plants due to several millennia in captivity. As oviposition substrate is provided by humans, this ability has become redundant. In the wild, however, selecting an adequate oviposition site is crucial for the survival of the offspring, and thus helps preserve the species.

On the other side, perception of the female-produced attractant bombykol in Bombyx mori males is unabated, although it is not necessary anymore to find the females, as they are presented to the males by the breeders. Probably because bombykol not only attracts males but also triggers mating behavior in the males, it has remained indispensable for reproductive success.

Domestication effects are localized on the sex chromosome

Unlike in mammals, the female ovule determines the sex of the offspring in moths and butterflies. The distinction is made, analogous to the XY chromosomes, between W and Z chromosomes. Males have ZZ, females WZ chromosomes. Because both species, B. mori and B. mandarina, can still be crossbred, the scientists bred hybrids and used them for further olfactory experiments. “The modification of the Bombyx mori olfactory system, namely the reduced perception of environmental odors, is very likely caused by mutations on the female W chromosome. Differences in the signal processing in the moth’s brain, however, are not located on the sex chromosomes,” Sonja Bisch-Knaden, first author of the study, summarizes the results of the hybrid experiments.

Combining classical methods of electroantennogram recordings with advanced imaging techniques to analyze responses in the olfactory centre of the silk moth brains opens new perspectives in olfactory research: from molecule to behavior. [AO/JWK]

Original Publication:
Bisch-Knaden, S., Daimon, T., Shimada, T., Hansson, B.S., Sachse, S. (2014). Anatomical and functional analysis of domestication effects on the olfactory system of the silkmoth Bombyx mori. Proc. R. Soc. B, 281: 20132582. DOI 10.1098/rspb.2013.2582

http://dx.doi.org/10.1098/rspb.2013.2582

Further Information:
Silke Sachse, MPI for Chemical Ecology, +49 3641 57-1416, ssachse@ice.mpg.de
Bill S. Hansson, MPI for Chemical Ecology, +49 3641 57-1401, hansson@ice.mpg.de
Contact and picture requests:
Angela Overmeyer M.A., MPI for Chemical Ecology, Hans-Knöll-Str. 8, 07743 Jena, Tel.: +49 3641 57-2110, overmeyer@ice.mpg.de

Angela Overmeyer | Max-Planck-Institut
Further information:
http://www.ice.mpg.de/ext/735.html

More articles from Life Sciences:

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

nachricht How protein islands form
15.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: Scientists improve forecast of increasing hazard on Ecuadorian volcano

Researchers from the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, the Italian Space Agency (ASI), and the Instituto Geofisico--Escuela Politecnica Nacional (IGEPN) of Ecuador, showed an increasing volcanic danger on Cotopaxi in Ecuador using a powerful technique known as Interferometric Synthetic Aperture Radar (InSAR).

The Andes region in which Cotopaxi volcano is located is known to contain some of the world's most serious volcanic hazard. A mid- to large-size eruption has...

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

New thruster design increases efficiency for future spaceflight

16.08.2017 | Physics and Astronomy

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017 | Materials Sciences

A new method for the 3-D printing of living tissues

16.08.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>