Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Australian fire beetle avoids the heat - Its infrared organs warn the insect of hot surfaces

15.02.2018

The Australian jewel beetle Merimna atrata has several heat sensors. Originally it was thought that it uses them to detect forest fires: The insect lays its eggs in the wood of burned eucalyptus trees. Researchers at the University of Bonn were finally able to refute this hypothesis. Instead, the beetle appears to need its heat sensors for a different purpose: to not burn its feet on landing. The study has now been published in the journal PLOS ONE.

The Australian fire beetle is attracted to freshly burnt wood. Experts also call this pyrophilia (“love of fire”). This behavior is not very common in insects. Merimna atrata however has a good reason for this: The dead wood provides plenty of food for the larvae of the beetle, so it uses the wood for oviposition.


The fire beetle is fixed in flight, but still able to turn left and right. Despite of good eyesight, beetles did not change direction when exposed to images of forest fire.

© Helmut Schmitz / University of Bonn

But how does Merimna find a freshly burned area? For some time it has been known that the fire beetle has heat sensors with which it can detect infrared radiation. In a sense, it “sees” hot places in its environment against a cooler background. It was originally believed that the insects use this ability to detect forest fires.

“However, the IR organs in Merimna atrata are relatively insensitive”, Dr. Helmut Schmitz emphasizes. Schmitz is a lecturer at the Institute of Zoology at the University of Bonn; he investigates thermo and infrared reception in the black insects for nearly two decades. “This actually contradicts the assumption that the IR organs enable the beetle to detect fires from a greater distance.”

Beetles stuck with glue

Together with his colleagues, Schmitz has now been able to demonstrate for the first time that these doubts are justified. The scientists designed an ingenious experiment for this purpose. Put simply, they stuck the beetles with their backs to the end of a pin and used this to hang them up. This left the experimental animals with the ability to fly continuously, but without moving forward. “More importantly: They were able to navigate in any direction, i.e. turning right or left”, emphasizes Schmitz.

Then the scientists stimulated the flying beetles with weak infrared radiation from the side. The beetles changed their flight direction in response, but always away from the source and never towards it.

“Merimna’s IR organs are located on both sides of its abdomen; incidentally, this is unique in the animal kingdom”, explains Schmitz. “When we occluded the IR receptors with aluminum foil, the animals no longer reacted to the radiation, but always carried on flying straight ahead. As soon as we removed the foil they displayed their original behavior again.” This observation suggests another use of the heat sensors: “Presumably they help the fire beetles avoid hot spots when approaching an oviposition site such as a freshly burnt branch; these hot spots are not visible with the naked eye to humans and animals during the day,” says Schmitz.

How the animals detect forest fires remains unclear. Even visual stimuli seem to play no role in fire detection, despite Merimna atrata having good eyesight. The researchers tested this hypothesis by showing the beetles slides of large clouds of smoke rising above a forest area. But the insects were completely unimpressed: They never changed their flight direction.

Following the nose

“We therefore assume that Merimna atrata gets its information about an ongoing fire from the smell of smoke”, concludes Helmut Schmitz. This is also important for another reason: Odors can tell you exactly what is actually burning. In contrast, this information cannot be inferred from the heat development or the appearance of a smoke plume. Merimna is very picky: It only lays its eggs in burnt eucalyptus wood and avoids other trees. If the insect was to rely on its IR sense, it would risk being lured into the wrong kind of fires.

Something quite different can be seen with a close European relative; the fire beetles of the genus Melanophila: Their larvae develop in a variety of trees. Heat perception would be quite worthwhile for them. In fact, Melanophila also has infrared sensors, but they are completely different. They can presumably detect infrared radiation even from a long distance: According to measurements and theoretical calculations, Melanophila heat sensors are at least 500 times more sensitive than those of Merimna atrata.

Publication: Marcel Hinz, Adrian Klein, Anke Schmitz and Helmut Schmitz: The impact of infrared radiation in flight control in the Australian “firebeetle” Merimna atrata; PLOS ONE; DOI: 10.1371/journal.pone.0192865

Contact:
PD Dr. Helmut Schmitz
Institute of Zoology at the University of Bonn
Telephone: 0228/73 20 71
Email: h.schmitz@uni-bonn.de

Dr. Andreas Archut | idw - Informationsdienst Wissenschaft
Further information:
http://www.uni-bonn.de/

Further reports about: beetle forest fires hot spots infrared radiation insect insects larvae

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Storage & Transport of highly volatile Gases made safer & cheaper by the use of “Kinetic Trapping"

Augsburg chemists present a new technology for compressing, storing and transporting highly volatile gases in porous frameworks/New prospects for gas-powered vehicles

Storage of highly volatile gases has always been a major technological challenge, not least for use in the automotive sector, for, for example, methane or...

Im Focus: Disrupting crystalline order to restore superfluidity

When we put water in a freezer, water molecules crystallize and form ice. This change from one phase of matter to another is called a phase transition. While this transition, and countless others that occur in nature, typically takes place at the same fixed conditions, such as the freezing point, one can ask how it can be influenced in a controlled way.

We are all familiar with such control of the freezing transition, as it is an essential ingredient in the art of making a sorbet or a slushy. To make a cold...

Im Focus: Micro energy harvesters for the Internet of Things

Fraunhofer IWS Dresden scientists print electronic layers with polymer ink

Thin organic layers provide machines and equipment with new functions. They enable, for example, tiny energy recuperators. In future, these will be installed...

Im Focus: Dynamik einzelner Proteine

Neue Messmethode erlaubt es Forschenden, die Bewegung von Molekülen lange und genau zu verfolgen

Das Zusammenspiel aus Struktur und Dynamik bestimmt die Funktion von Proteinen, den molekularen Werkzeugen der Zelle. Durch Fortschritte in der...

Im Focus: Dynamics of individual proteins

New measurement method allows researchers to precisely follow the movement of individual molecules over long periods of time

The function of proteins – the molecular tools of the cell – is governed by the interplay of their structure and dynamics. Advances in electron microscopy have...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

5th International Conference on Cellular Materials (CellMAT), Scientific Programme online

02.10.2018 | Event News

Major Project: The New Silk Road

01.10.2018 | Event News

"Boston calling": TU Berlin and the Weizenbaum Institute organize a conference in USA

21.09.2018 | Event News

 
Latest News

Physics: Not everything is where it seems to be

15.10.2018 | Physics and Astronomy

Microfluidic molecular exchanger helps control therapeutic cell manufacturing

15.10.2018 | Life Sciences

Link between Gut Flora and Multiple Sclerosis Discovered

15.10.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>