Symbiosis


This topic concerns microbes associated with insects in all ways, shapes
and forms. Traditionally this has meant endosymbionts contributing to
the nutrition of the host insects and this is certainly a rich field
full of examples, especially from the Hemiptera, plant and blood-sucking
insects. In more recent times the discovery of Wolbachia bacteria, and
especially the great little book, "Influential passengers:  inherited
microorganisms and arthropod reproduction," [edited by Scott L. O'Neill,
Ary A. Hoffmann, and John H. Werren, Oxford University Press, New York,
1997] has spurred great interest in this field. The book chronicles the
discovery of Wolbachia and its influence on the reproductive strategies
of host insects. There is an international meeting that takes place
every couple of years (Kolymbari, Crete, July 9-15, 2002, hosted by
Kostas Bourtzis and organised by Kostas, Claudio Bandi, O'Neill, Richard
Stouthamer and Jack Werren, the pioneers of this field). Scott O'Neill
just hosted the latest of these meetings on Heron Island, Australia as a
satellite following the Entomology Congress held in Brisbane, 15-21
August 2004. There is a Wolbachia web site; there is a Wolbachia
genomone project.

The Wolbachia web site: http://www.wolbachia.sols.uq.edu.au/index.html

The International Symbiosis Society (ISS) is very active and increasing
membership rapidly. You can find out about them at:
http://people.bu.edu/iss/. They meet on a regular basis. The next
scheduled meeting is in Vienna in 4-10 August 2006.

Kostas Bourtzis and I put together a book of 18 contributed chapters on
the subject of Insect Symbiosis, CRC Press, 2003. In one year they sold
half of the first run and have reprinted another 300 copies already. CRC
Press asked for another version and it is now in the development stages.
A quick look at Insect Symbiosis provides a good grasp of the influence
of symbionts on the biology of insects. My personal favorite example is
Chapter 5 written by Abdelaziz Heddi that describes the role of
symbionts in the biology of the rice weevil. When Paul Nardon first
described this case, it appeared under in PNAS under the title: "Four
intracellular genomes direct weevil biology: nuclear, mitochondrial,
principal endosymbionts, and Wolbachia." Not only is this the best title
I have read for a biology paper, the paper itself is the best one I have
read in the past ten years and I tell all visitors that. It reports that
if you cure rice weevil of its principle endosymbiont (PE), the weevil
loses its ability to fly because the PE has taken over the role of
supplying pantothenic acid, a cofactor for flight metabolism. If this
doesn't convince entomologists and physiologist that they cannot ignore
symbionts any longer, nothing will.

I am now convinced that we cannot fully understand the physiology and
behavior our experimental insect subjects unless we take into account
the role of the symbionts. That is why a section on SYMBIOSIS was added
to our web site as a major subtopic. The 18 chapters in Insect Symbiosis
(2003) could provide the basis of a one hour lecture in an insect
physiology class to introduce the concept of symbiosis in the context of
insect physiology. Besides my favorite topic of rice weevils described
above, there are examples of gut bacteria providing secondary
metabolites that produce odors in feces of termites that are used for
nest-mate recognition. Any change in these odors spells death or
ejection from the colony by soldiers.

There are a number of Wolbachia papers describing effects on
reproductive strategies, male-killing properties of other symbionts hav
to become important to understanding reproductive physiology and the
co-evolution of certain fungi with bark beetles is necessary to know for
understanding of beetle biology. Claudi Bandi is widely known for
characterizing Wolbachia in nematodes and the discovery that the
breakdown of endotoxin-like products from Wolbachia itself from filarial
nematode infections of humans is the direct cause of defensive reactions
that lead to river blindness changed the way one thinks about this
devasting affliction caused by black flies transmission of the filaria
nematodes with their Wolbachia infections. 

The purpose of this web site it to facilitate contact between workers in
symbiosis and to inform teachers of insect physiology about the latest
advances in this field as might impact the teaching of insect
physiology.

 

-Symbiotic Control Website by Dr. Miller here

 

Click on the picture to go to Dr. Miller's Lab Web Page.

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