Figure 1. Right IR organ of Melanophila acuminata (head is up).
by Helmut Schmitz1*, Herbert Bousack2
1 Institut für Zoologie der Universität Bonn, Bonn, Germany, 2 Peter Grünberg Institut, Forschungszentrum Jülich GmbH, Jülich, Germany
Abstract
Pyrophilous jewel beetles of the genus Melanophila approach forest fires and there is considerable evidence that these beetles can detect fires from great distances of more than 60 km. Because Melanophila beetles are equipped with infrared receptors and are also attracted by hot surfaces it can be concluded that these infrared receptors are used for fire detection.
The sensitivity of the IR receptors is still unknown. The lowest threshold published so far is 0.6 W/m2 which, however, cannot explain the detection of forest fires by IR radiation from distances larger than approximately 10 km. To investigate the possible sensitivity of the IR receptors we assumed that beetles use IR radiation for remote fire detection and we made use of a historic report about a big oil-tank fire in Coalinga, California, in 1924. IR emission of an oil-tank fire can be calculated by “pool fire” simulations which now are used for fire safety and risk analysis. Assuming that beetles were lured to the fire from the nearest forests 25 and 130 km away, our results show that detection from a distance of 25 km requires a threshold of the IR receptors of at least 3×10?2 W/m2. According to our investigations most beetles became aware of the fire from a distance of 130 km. In this case the threshold has to be 1.3×10?4 W/m2. Because such low IR intensities are buried in thermal noise we suggest that the infrared sensory system of Melanophila beetles utilizes stochastic resonance for the detection of weak IR radiation. Our simulations also suggest that the biological IR receptors might be even more sensitive than uncooled technical IR sensors. Thus a closer look into the mode of operation of the Melanophila IR receptors seems promising for the development of novel IR sensors.
Citation: Schmitz H, Bousack H (2012) Modelling a Historic Oil-Tank Fire Allows an Estimation of the Sensitivity of the Infrared Receptors in Pyrophilous Melanophila Beetles. PLoS ONE 7(5): e37627. doi:10.1371/journal.pone.0037627
Editor: Jochen Zeil, The Australian National University, Australia
Received: December 22, 2011; Accepted: April 26, 2012; Published: May 21, 2012
Copyright: © 2012 Schmitz and Bousack. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This work was funded by the German Ministry of Education and Research (BMBF): www.bmbf.de Grant No.: 01RB0909A. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
* E-mail: h.schmitz@uni-bonn.de
Web Link to the complete Article content, including citations: www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0037627
