ABSTRACT
Herbert Bousack, Helmut Budzier, Gerald Gerlach, and Helmut Schmitz
Buprestid beetles of the genus Melanophila inhabit the palaearctic as well as the nearctic parts of the world. As a special behavioral feature, beetles of both sexes approach forest fires because their brood depends on burnt wood as larval food (Champion 1909, Linsley 1943). Initially, the fresh burnt area serves as a meeting place where the males search for females. After mating, the females deposit the eggs under the bark of the burnt trees. However,
CONTENTS
4.1 Melanophila .................................................................................................. 117 4.1.1 Structure and Function of the Sensilla ....................................... 118 4.1.2 Sensitivity of the IR Receptor of the Beetle Melanophila
acuminata ......................................................................................... 119 4.2 Principle of a Sensor Based on the IR Receptor ..................................... 121
4.2.1 Sensor Model .................................................................................. 121 4.2.2 Pressure Increase of the Cavity and Deflection of the
Membrane ....................................................................................... 122 4.3 Noise in Golay Cells and in the Photomechanic IR Receptor ............. 128
4.3.1 Noise Sources in Golay Cells ....................................................... 128 4.3.1.1 Temperature Fluctuation Noise .................................... 129 4.3.1.2 Mechanical-Thermal Noise ............................................ 129 4.3.1.3 Readout Noise .................................................................. 130 4.3.1.4 Total Noise ....................................................................... 131
4.3.2 Detectivity of Golay Cells ............................................................. 131 4.3.3 Noise Sources in IR Receptors ..................................................... 132
4.4 Measurement of IR Radiation below the Noise Level .......................... 132 4.5 Influence of the Fluid in the Cavity ........................................................ 133 4.6 Experimental Results and Devices .......................................................... 135 References ............................................................................................................. 137
the outbreak of a forest fire is highly unpredictable. Because finding a fire is crucial for the survival of all Melanophila species, Melanophila beetles should be able to detect fires from distances as large as possible. Therefore, it is reasonable to suppose that the sensory organs that are used for fire detection have been subjected to a strong evolutionary pressure especially with regard to sensitivity. For the detection of fires, Melanophila beetles are equipped with special infrared (IR) receptors (Evans 1964, 1966, Schmitz and Bleckmann 1997).
