Tangled web of the insect, plant and parasite arms race

October 31, 2007

New insights into the evolutionary relationship between plant-dwelling insects and their parasites are revealed in the online open access journal BMC Biology. Researchers shed light on how sawflies evolved to escape their parasites and gain themselves an 'enemy-free space' for millions of years.

Tommi Nyman of the University of Joensuu in Finland together with colleagues from Sweden and Germany uncovered a food web involving willow trees, sawflies, and the parasites feeding on sawfly larvae. Sawflies (a group of insects related to bees and wasps) lay their larvae in willows creating galls, which are protruding growths of plant tissue. Nyman's group used data from galls collected from willows over an 18-year period. They classified 43 sawfly species using genetic analysis and assessed the degree of parasitism to which these insects had been subjected by 72 different parasites.

Their statistical analysis showed that parasitism promotes the insects' ecological divergence in a co-evolutionary arms race. The sawflies develop new gall-types and, in doing so, can escape the attentions of the parasites without having to switch host plant. Some parasites, however, have in turn adapted to the divergence in gall-types, driving further speciation. These processes partly explain the unusual diversity of herbivorous insects and their parasitoids.

This study is the first time that key co-evolutionary hypotheses such as the classic Escape-And-Radiate (EAR) hypothesis have been tested in a phylogenetic framework. EAR suggests that hyper diverse communities result from co-evolutionary arms races featuring cycles of enemy escape, radiation, and colonization by new enemy lineages. The results show that the EAR hypothesis is too simplistic to be applied to complex species-rich food webs.

"Our results indicate that niche-dependent parasitism is a major force promoting ecological divergence in herbivorous insects," says Nyman. "Diversification seems to be spurred by a continuous stepwise process, in which ecological and phenotypic shifts in prey lineages are followed by a lagged evolutionary response by some of the associated enemies."
-end-
Article:
Reciprocal diversification in a complex plant-herbivore-parasitoid food web
Tommi Nyman, Folmer Bokma and Jens-Peter Kopelke
BMC Biology (in press)

During embargo, article available at: http://www.biomedcentral.com/imedia/1208326150161328_article.pdf?random=840595

After the embargo, article available from the journal website at: http://www.biomedcentral.com/bmcbiol/

Article citation and URL available on request at press@biomedcentral.com on the day of publication

Please quote the journal in any story you write. If you are writing for the web, please link to the article. All articles are available free of charge, according to BioMed Central's Open Access policy.

For author contact details please contact Sari Eskelinen Tiedottaja (Press Office, University of Joensuu)
Phone: +358 13-251 2077
Email: sari.eskelinen@joensuu.fi

BioMed Central

Related Parasites Articles from Brightsurf:

When malaria parasites trick liver cells to let themselves in
A new study led by Maria Manuel Mota, group leader at Instituto de Medicina Molecular, now shows that malaria parasites secrete the protein EXP2 that is required for their entry into hepatocytes.

How deadly parasites 'glide' into human cells
A group of scientists led by EMBL Hamburg's Christian Löw provide insights into the molecular structure of proteins involved in the gliding movements through which the parasites causing malaria and toxoplasmosis invade human cells.

How malaria parasites withstand a fever's heat
The parasites that cause 200 million cases of malaria each year can withstand feverish temperatures that make their human hosts miserable.

New studies show how to save parasites and why it's important
An international group of scientists published a paper, Aug. 1, 2020, in a special edition of the journal Biological Conservation that lays out an ambitious global conservation plan for parasites.

More flowers and pollinator diversity could help protect bees from parasites
Having more flowers and maintaining diverse bee communities could help reduce the spread of bee parasites, according to a new study.

How Toxoplasma parasites glide so swiftly (video)
If you're a cat owner, you might have heard of Toxoplasma gondii, a protozoan that sometimes infects humans through contact with contaminated feces in litterboxes.

Parasites and the microbiome
In a study of ethnically diverse people from Cameroon, the presence of a parasite infection was closely linked to the make-up of the gastrointestinal microbiome, according to a research team led by Penn scientists.

Clocking in with malaria parasites
Discovery of a malaria parasite's internal clock could lead to new treatment strategies.

Feeding bluebirds helps fend off parasites
If you feed the birds in your backyard, you may be doing more than just making sure they have a source of food: you may be helping baby birds give parasites the boot.

Scientists discover how malaria parasites import sugar
Researchers at Stockholm University has established how sugar is taken up by the malaria parasite, a discovery with the potential to improve the development of antimalarial drugs.

Read More: Parasites News and Parasites Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.