Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Bugs need symbiotic bacteria to exploit plant seeds

09.01.2013
While common firebugs have no impact on humans, their relatives, the cotton stainers, are serious agricultural pests. Researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, recently discovered that these bugs need bacterial symbionts to survive on cotton seeds as their sole food source.

Removal of the symbionts or reciprocal exchange of bacteria between firebugs and cotton stainers led to high mortality and low mating success, demonstrating the importance of the bacterial helpers for growth and reproduction. Thus, symbiotic bacteria constitute a key factor not only for the ecological success of firebugs but also for the pest status of cotton stainers.


The African cotton stainer (Dysdercus fasciatus) cultivates bacterial symbionts in its mid-gut that are necessary for growth and reproduction.
Photo: MPI for Chemical Ecology/Kaltenpoth


Firebugs (Pyrrhocoris apterus)
Photo: MPI for Chemical Ecology/Kaltenpoth

Aggregations of the red and black colored firebugs are ubiquitous under linden trees in Central Europe, where the bugs can reach astounding population densities. While these insects have no impact on humans, their African, Asian, and American relatives, the cotton stainers, are serious agricultural pests of cotton and other Malvaceous plants. Researchers at the Max Planck Institute for Chemical Ecology in Jena, Germany, recently discovered that these bugs need bacterial symbionts to survive on cotton seeds as their sole food source.

By using high-throughput sequencing technologies, they found out that firebugs and cotton stainers share a characteristic bacterial community that colonizes a specific region of their mid-gut. Removal of the symbionts or reciprocal exchange of bacteria between firebugs and cotton stainers led to high mortality and low mating success, demonstrating the importance of the bacterial helpers for growth and reproduction. Thus, symbiotic bacteria constitute a key factor not only for the ecological success of firebugs but also for the pest status of cotton stainers. (Molecular Ecology, December 2012; Environmental Microbiology, in press)

With more than 80,000 described species, the true bugs represent one of the five megadiverse insect orders on earth. Many species are serious agricultural pests that are responsible for significant losses in crop production. Among these are cotton stainers, bugs of the family Pyrrhocoridae that damage cotton by feeding on the seed bolls and leaving indelible stains in the harvested crop. While previous research on sap-sucking insects demonstrated that they rely on microbial symbionts for nutrition, it remained unknown how cotton stainers and other seed-feeding bugs exploit Malvaceous plant seeds that are rich in toxic secondary metabolites, but poor in some essential nutrients.

Scientists of the Insect Symbiosis Research Group at the Max Planck Institute for Chemical Ecology set out to address this question and elucidate the possible role of symbiotic bacteria in the nutrition of firebugs and cotton stainers. By using high-throughput sequencing technologies and deciphering almost 300,000 copies of bacterial 16S rRNA genes, they discovered that the bugs cultivate a characteristic community of three to six bacterial symbionts in a specific mid-gut region. “The symbionts are transferred to the eggs by female bugs, and the hatchlings later take them up by probing the egg surface,” explains Sailendharan Sudakaran, PhD student in the Insect Symbiosis Group. “This guarantees that the bugs maintain the symbionts throughout their entire life and pass them on to the next generation.” Bugs from different localities and even across different species showed very similar microbial communities, indicating that the bugs have been associated with their symbionts over millions of years.

To find out whether the bacterial symbionts help the bugs to survive on the plant seeds as their sole food source, the researchers performed a simple yet elegant experiment: They dipped bug eggs into bleach and ethanol and thereby killed the microbial community on the surface without harming the developing egg itself. Some of the eggs were then re-infected with a mixture of bacteria from an adult bug’s gut, while others remained symbiont-free. Interestingly, the symbiont-free individuals showed markedly higher mortality, needed longer to develop into adults, and produced much fewer offspring than bugs with their native symbionts. “Symbiont-free bugs showed clear signs of malnutrition, although they were fed on the same plant seeds as their symbiont-bearing counterparts. This can only be explained by an important contribution of the bacteria towards host nutrition”, says Hassan Salem, another PhD student in the group. Surprisingly, exchanging bacterial communities between firebugs and cotton stainers also resulted in reduced fitness of both species, indicating that – despite their similarity – the symbioses are highly specific.

The next important steps will be to find out whether the bacterial symbionts provide essential nutrients to their hosts that are lacking in the seed diet, or whether they help by detoxifying the noxious defensive chemicals of the plant. “Firebugs and cotton stainers are ideal model systems to address fundamental questions in insect symbiosis, because we can manipulate and exchange their microbial communities and then measure the fitness of the hosts,” explains Martin Kaltenpoth, head of the Max Planck Research Group Insect Symbiosis. “Detailed knowledge on how insects interact with microbial symbionts is essential for an understanding of insect physiology, ecology, and evolution.”

In the case of agricultural pest insects like the cotton stainers, this knowledge may also provide novel leads for biological control. [MK]

Original Publications:
Sudakaran, S., Salem, H., Kost, C. & Kaltenpoth, M. (2012) Geographic and ecological stability of the symbiotic mid-gut microbiota in European firebugs, Pyrrhocoris apterus (Hemiptera; Pyrrhocoridae). Molecular Ecology 21: 6134-6151.
http://dx.doi.org/10.1111/mec.12027
Salem, H., Kreutzer, E., Sudakaran, S. & Kaltenpoth, M. (in press) Actinobacteria as essential symbionts in firebugs and cotton stainers (Hemiptera, Pyrrhocoridae). Environmental Microbiology, DOI:10.1111/1462-2920.12001

http://dx.doi.org/10.1111/1462-2920.12001

Further Information:
Dr. Martin Kaltenpoth, +49 3641 57-1800, mkaltenpoth@ice.mpg.de
Picture and Movie Requests:
Angela Overmeyer M.A., +49 3641 57-2110, overmeyer@ice.mpg.de
or Download via http://www.ice.mpg.de/ext/735.html

Dr. Jan-Wolfhard Kellmann | Max-Planck-Institut
Further information:
http://www.ice.mpg.de
http://www.ice.mpg.de/ext/976.html?&L=0

More articles from Life Sciences:

nachricht Newly designed molecule binds nitrogen
23.02.2018 | Julius-Maximilians-Universität Würzburg

nachricht Atomic Design by Water
23.02.2018 | Max-Planck-Institut für Eisenforschung GmbH

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Attoseconds break into atomic interior

A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.

In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...

Im Focus: Good vibrations feel the force

A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.

By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Basque researchers turn light upside down

23.02.2018 | Physics and Astronomy

Finnish research group discovers a new immune system regulator

23.02.2018 | Health and Medicine

Attoseconds break into atomic interior

23.02.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>