Electrophysiological characterization of the cold receptors in the ground beetle Pterostichus oblongopunctatus
Institute of Plant Protection, Estonian Agricultural University, Kreutzwaldi 64, 51014 Tartu, Estonia; e-mail: email@example.com
Several insects possess thermoreceptors, which aid them in feeding and survival. Campaniform sensilla at the tip of antennae of ground beetlePterostichus oblongopunctatus (Fab., 1787) (Coleoptera, Carabidae) show action potentials of the three sensory cells, A-, B- and C-cells, different in their spike amplitudes. Only the A-cell, with the largest spike amplitude, is highly sensitive to temperature fluctuations, showing remarkable changes in its firing rate induced already by changes in temperature of 0.1°C. A-cells respond to a rapid temperature drop with a strong phasic-tonic reaction; larger decreases in temperature evoke higher peak frequency values. Maximum peak frequencies in A-cells, varying from 344–588 Hz in different specimens, are induced by temperature drop of 7.9–15.7°C, whereas temperature rise strongly inhibits impulse activity of the A-cell. Number of action potentials per first second of response of eight beetles’ was very various, from 7 to 210 impulses, induced by temperature drop from 0.1 to 14.6°C, higher temperature decreased the number of impulses. This knowledge serves as prerequisite information for future electrophysiological studies related to different habitat selection of ground beetles’.