The Spider that Carries a Secret
The wasp spider (Argiope bruennichi) is large and conspicuous, and is rapidly colonizing new territory northwards in Europe. Although the reasons for the rapid range expansion are still unclear, a new study carried out by a team of researchers from the University of Greifswald and elsewhere in Germany has unveiled a secret in the tissues of female and juvenile wasp spiders. The team set out to study the diverse collection of bacteria, the so-called microbiome that the wasp spider carries (like most other animals, including humans).
What they found was striking: sequencing analysis revealed that one single bacterial type makes up >90% of the microbiome and this bacterial sequence does not closely resemble anything known to science. The results of the study were recently published in the journal Microorganisms (DOI: 10.3390/microorganisms8010008) http://doi.org/10.3390/microorganisms8010008.
Grasslands and abandoned backyards around Europe are hunting grounds for the wasp spider (Argiope bruennichi). One hundred years ago, this species could only be found in Europe in areas with a Mediterranean climate. In the last century, and more rapidly during the last decade, it has spread from those warm regions into much colder territories – as far north as coastal Estonia, Finland and Sweden – catching the attention of scientists who are searching for the key to its recent success. One such scientist, Monica M. Sheffer, a doctoral researcher in the RESPONSE Research Training Group https://biologie.uni-greifswald.de/forschung/dfg-graduiertenkollegs/research-training-group-2010/ at the University of Greifswald, studies many aspects of the spider’s biology for this reason. She led a study on the spider’s microbiome (the assemblage of bacteria within a host) that can have diverse impacts on hosts – including changing their dispersal behaviour.
The spiders for this study were collected from two populations: one in Greifswald and one in Estonia. Because the microbiome often varies depending upon the tissue type investigated, the researchers dissected the spiders and sequenced the microbiome of every tissue type. They also sequenced the microbiome of juvenile spiders (“spiderlings”) to see if any bacteria were passed from mother to offspring.
The sequencing analysis yielded an unexpected and exciting result: one single type of bacteria dominated every tissue type of the adults, and had been passed on to the spiderlings. Dubbed “DUSA” (Dominant Unknown Symbiont of Argiope bruennichi), this bacterium is unlike any other previously known bacterial species. The study revealed that it belongs to the phylum of Tenericutes, but it is highly divergent.
The authors suggest that the presence of DUSA in all investigated tissues of spiders from both Germany and Estonia could represent an intimate symbiosis between the spider and a bacterium. Such symbioses are common for Tenericute bacteria, and are known to change the behaviour of the host in other spiders and insects. Future studies will investigate whether more remote spider populations also carry this bacterium and if the symbiont could help the spider on its northward journey through Europe.
The concept for this study was developed thanks to the University of Greifswald’s Mentoring Programme, as the programme connected Prof. Dr. Gabriele Uhl, a researcher whose work also approaches the range expansion of Argiope bruennichi, with Dr. Mia M. Bengtsson, a microbiologist studying the interactions of microbes and their hosts. Together, they were inspired to share their expertise and look into the microbiome of the wasp spider, and supervised Monica M. Sheffer in her investigations. Prof. Dr. Tim Urich, also from the University of Greifswald and collaborators Dr. Stefan Prost (Senckenberg, Frankfurt) and Prof. Dr. Tillmann Lueders (University of Bayreuth) brought in additional expertise and infrastructure for the research project.
Sheffer, M.M.; Uhl, G.; Prost, S.; Lueders, T.; Urich, T.; Bengtsson, M.M. 2020. Tissue- and population-level microbiome analysis of the wasp spider Argiope bruennichi identified a novel dominant bacterial symbiont. Microorganisms 8: 8. DOI: doi.org/10.3390/microorganisms8010008
A female wasp spider, Argiope bruennichi, in her web. Photo by G. Uhl
Monica Sheffer finding a female wasp spider, Argiope bruennichi, in the field in Portugal. Photo by M.M. Sheffer.
Zoological Institute and Museum https://zoologie.uni-greifswald.de/en/
General and Systematic Zoology https://zoologie.uni-greifswald.de/en/organization/departments/general-and-systematic-zoology/
Microbial Physiology and Molecular Biology https://mikrobiologie.uni-greifswald.de/en/information/chairs/microbial-physiology-and-molecular-biology/
Contact at the University:
Monica M. Sheffer & Gabriele Uhl
Zoological Institute and Museum
General and Systematic Zoology
Loitzer Straße 26, 17489 Greifswald
Dr. Mia M. Bengtsson
Microbial Physiology and Molecular Biology
Felix-Hausdorff-Straße 8, 17489 Greifswald
Tel.: +49 3834 420 5918