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 Zeolite catalysts pave the road to decentral chemical processes Confined space increases reactivity
28.06.2017 | Technische Universität München

nachricht For a chimpanzee, one good turn deserves another
27.06.2017 | Max-Planck-Institut für Mathematik in den Naturwissenschaften (MPIMIS)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Extensive Funding for Research on Chromatin, Adrenal Gland, and Cancer Therapy

28.06.2017 | Awards Funding

Predicting eruptions using satellites and math

28.06.2017 | Earth Sciences

Extremely fine measurements of motion in orbiting supermassive black holes

28.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>