Nocturnal activity of Carabus hortensis L. [Coleoptera, Carabidae] in two forest sites studied with harmonic radar method

The paper deals with a study of the nocturnal activity rhythm of Carabus hortensis L. with applying a harmonic radar system. Beetles with a diode attached to their elytra were set into the terrain and tracked by help of a portable radar. The studies were carried out in a pine forest in which Carabus hortensis L. occurs regularly and in a beech forest in which this species was completely absent. The data show that Carabus hortensis L. is active mainly at the first hours after sunset, independently from time of sunset. A small peak of activity exists at about 9–10 hours after sunset. The nocturnal activity rhythm is similar in both forest sites, but the individuals show significantly higher activity in the beech forest. Based on the assumption that activity is connected with hunger level, the total activity may be useful as indicator of habitat quality (feeding conditions) for Carabus hortensis L.