Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Asian lady beetles use biological weapons against their European relatives

17.05.2013
Invasive species from Eastern Asia uses microsporidia in order to out-compete native lady beetles.

Once introduced for biological pest control, Asian lady beetle Harmonia axyridis populations have been increasing uncontrollably in the US and Europe since the turn of the millennium.


During spring and fall, mass occurrences of the Asian lady beetle can often be observed.
Andreas Vilcinskas, Justus Liebig University, Giessen

The species has been proliferating rapidly in Germany; conservationists fear that the Asian lady beetle will out-compete native beetle species. Scientists from the University of Giessen and the Max Planck Institute for Chemical Ecology in Jena, Germany, have now found the reason why this animal is so successful.

Apart from a strongly antibiotic substance − a compound called harmonine − and antimicrobial peptides, its body fluid, the hemolymph, contains microsporidia. These tiny fungus-like protozoa parasitize body cells and can cause immense harm to their host. The Asian lady beetle is obviously resistant to these parasites in its own body. However, transferred to native species, microsporidia can be lethal. SCIENCE, May 17, 2013, DOI: 10.1126/science.1234032)

The Asian lady beetle − a model organism for studying biological invasions

Because of its delicate, yet extremely variable, patterning, the lady beetle species Harmonia axyridis is sometimes called Harlequin ladybird. However, this insect has no comical characteristics. At the end of the last century, the species − which is native e.g. in China and Japan and therefore called Asian lady beetle − was successfully used in European greenhouses to keep aphid populations in check: It can devour hundreds of aphids per day, as well as many bug species or insect eggs. Yet today, this “bio killer” has escaped from the greenhouses and is spreading massively, but: A rapid and successful propagation of a neozoon − the biological term for a species which is invading new habitats and ecosystems − is not just an inevitable matter of course.

In most cases, such a neozoon species doesn’t survive or else its population density remains very low, because original and adapted life forms usually prevail in their ecological niche and win interspecific competitions. However, as soon as Harmonia axyridis is released into nature, it invades all habitats, especially those occupied by beetle species that feed on aphids. Within a very short period of time, native beetles are out-competed and the intruders have taken over. During the fall, major congregations of Asian lady beetles can be observed as swarms of insects search for hibernation places in houses or other sheltered areas.

They are not only a nuisance, they can also cause serious allergic reactions in humans. When prey becomes scarce, Asian lady beetles may feed on grapes as a substitute diet and hence, they are often found on grape-vines in vineyards in the fall. Once in the mash, the defensive chemical substances in their hemolymph negatively affect the taste of wine.

Like most ladybug species, the Asian lady beetle reflexively secretes fluid from its hemolymph as soon as it is attacked by potential enemies. Hemolymph fluid contains toxins and is therefore defensive. Can the Asian lady beetle’s secret of success be found in the hemolymph?

Microsporidia, tiny parasites present in the hemolymph of Harmonia axyridis, are the key to successfully out-competing native species

In comparison to other ladybug species, the hemolymph of H. axyridis contains a wide range of different antibacterial peptides − small proteins that insects use to fend off pathogens. Andreas Vilcinskas, Justus Liebig University in Giessen, Germany, and Heiko Vogel, Max Planck Institute for Chemical Ecology in Jena, Germany, studied the complex immune system of the insects and were able to isolate the genes that encode the enormous antimicrobial repertoire of H. axyridis. The hemolymph also contains a special substance, harmonine, which has a strongly antibacterial effect. Harmonine is only found in the hemolymph of H. axyridis, where is it abundant. Both the proteins and harmonine are of interest in medical research where they offer promising targets for the development of novel antibiotics, potentially even those against malaria.
When H. axyridis and its relative Coccinella septempunctata, which is native to Germany, are infected with pathogenic bacteria, both beetle species produce antibacterial peptides. However, the Asian lady beetle switches from a general hygiene using harmonine to an effective defense strategy based on dozens of peptides. “This alone, however, does not answer our main question: Is such a strong immune system, capable of fending off pathogens, the sole reason why H. axyridis is conquering the habitats of other beetle species all over the world? Can Harmonia out-compete other species just because it is more resistant to pathogens and, as a consequence, has a better chance to survive − or do other important factors play a role?” asks Heiko Vogel. Although lady beetles generally compete for their common food source, aphids, some beetles also eat each other. This phenomenon, called intraguild predation, is an important factor in the competition among predating lady beetles − especially if they compete against the particularly aggressive invader H. axyridis. H. axyridis can feed on native lady beetles without harmful consequences. In contrast, native lady beetles that feed on H. axyridis die. How can that be?

A key experiment provided the answer to this question. The hemolymph of H. axyridis contains, apart from harmonine and antimicrobial peptides, a third defensive component: tiny biological weapons called microsporidia. These spores enable the invader to infect other beetle species, mainly because it is common among lady beetles to predate the eggs and larvae of other species. In their experiment, the scientists first injected harmonine into native C. septempunctata lady beetles, to establish whether this chemical substance harms the insects. In fact, the injection of hemolymph or purified microsporidia from H. axyridis had lethal consequences. A look through a high-resolution microscope revealed innumerable tiny spores in the hemolymph of the Asian lady beetle, spores that were even tinier than hemocytes. Microsporidic spores “germinate” and attack the cells of C. septempunctata; however, they do not germinate in H. axyridis. The Asian lady beetle can disable these biological weapons in its own hemolymph, but the spores become active as soon as they reach the body fluid of other beetle species. H. axyridis’ very strong immunity against pathogens and the effect of the microsporidia may explain the ecological success of the Asian invader as it continues to out-compete native species across Europe. Now the researchers are interested in finding out how H. axyridis can disable the microsporidia in its own hemolymph. [JWK/AO]
Original Publications:

Vilcinskas, A., Stoecker, K., Schmidtberg, H., Röhrich, C., Vogel, H. (2013). Invasive harlequin ladybird carries biological weapons against native competitors. SCIENCE. May 17, 2013, DOI: 10.1126/science.1234032

http://dx.doi.org/10.1126/science.1234032

Schmidtberg, H., Röhrich, C., Vogel, H., Vilcinskas, A. (2013). A switch from constitutive chemical defense to inducible innate immune responses in the invasive ladybird Harmonia axyridis. Biology Letters 9: 20130006.

http://dx.doi.org/10.1098/rsbl.2013.0006

Vilcinskas, A., Mukherjee, K., Vogel, H. (2013). Expansion of the antimicrobial peptide repertoire in the invasive ladybird Harmonia axyridis. Proceedings of the Royal Society of London Series B - Biological Sciences. 280: 20122113.
http://dx.doi.org/10.1098/rspb.2012.2113

Further Information

Prof. Dr. Andreas Vilcinskas, +49 641 9937-600, Andreas.Vilcinskas@agrar.uni-giessen.de
Dr. Heiko Vogel, +49 3641 57-1512, hvogel@ice.mpg.de

Picture Requests:

Angela Overmeyer M.A., +49 3641 57-2110, overmeyer@ice.mpg.de or via download from http://www.ice.mpg.de/ext/735.html

Angela Overmeyer | Max-Planck-Institut
Further information:
http://www.ice.mpg.de/ext/1025.html?&L=0

More articles from Life Sciences:

nachricht Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute

nachricht Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften 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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>