A new type of insect infrared organ of low thermal mass

Abstract

The Australian beetle Acanthocnemus nigricans is attracted by forest fires and has a pair of complex infrared (IR) receptor organs on the first thoracic segment. Each organ consists of a tiny sensory disc (diameter 120-130 microm) which serves as an absorbing structure for IR radiation. The disc is arranged above an air-filled cavity which is located just anteriorly to the coxae of the prothoracic legs. Inside the disc, about 30 multipolar thermoreceptors (warmth receptors) are tightly attached to the cuticle which is directed to the outside. The many dendrites of each multipolar neuron are tightly wrapped around the soma and contain a large number of mitochondria. Absorption of IR radiation by the disc causes an increase in temperature which is measured by the warmth receptors. Therefore, the IR receptors of A. nigricans can be classified as microbolometers with reduced thermal mass and in principle can be compared to the IR organs of pit vipers.

Distribution of saproxylic beetles in a recently burnt landscape of the northern boreal forest of Québec

“…Indeed, it is generally assumed that early colonizer saproxylic species have great dispersal and detection capacities (Bouget, 2005;Byers, 2000) considering the ephemeral and unpredictable suitability of the burned substrate. Several are known to be attracted by smoke (Frost, 1984), infrared (Schmitz et al, 2002) or volatile organic compounds released by freshly firekilled trees or use kairomones emitted by their prey (Allison et al, 2004) sometimes at great distances (Franklin et al, 2000;Turchin and Thoeny, 1993). For example, experimental studies in flight mills revealed that many of these species are capable of flying up to several tens of kilometres (Atkins, 1961;Jactel and Gaillard, 1991).…”

Infrared light detection by the haller’s organ of adult american dog ticks, Dermacentor variabilis (Ixodida: Ixodidae)

“…In insects, there are two types of IR-sensing organs: (Type 1) photomechanic sensilla found in Melanophila beetles (Evans, 1964; Schmitz et al, 1997; Schmitz et al, 1998) and (Type 2) photothermal microbolometers found in the Merimna Australian fire-beetles (Schmitz et al, 2000; Schmitz et al, 2001; Schmitz et al, 2002) that are structurally and functionally similar to the pit organ IR detectors in snakes (Gracheva et al, 2010). Gracheva et al (2010) used an unbiased transcriptional profiling method to identify the IR receptors in snakes as transient receptor potential cation channel, subfamily A, member 1 (TRPA1) channels.…”

Daily activity and flight behaviour of adults of Capnodis tenebrionis (Coleoptera: Buprestidae)

“…Furthermore, physical factors such as infrared radiation can influence the flight performance of some insects. Species of Coleoptera, like Melanophila acuminata De Geer, Merimna atrata (Laporte & Gory) (Buprestidae) and Acanthocnemus nigricans (Hope) (Acanthocnemidae), endowed with IR receptor organs, use IR to correct flight direction in order to locate forest fires (Evans, 1966;Schmitz & Bleckmann, 1998;Schmitz et al, 2000Schmitz et al, , 2002.…”