The effect of food odour on food preference, activity and density of dung beetle Geotrupes stercorosus [Scriba, 1791] in a mixed coniferous forest

The response of coprophagous dung beetles Geotrupes stercorosus (Scriba, 1791) to the additional food supply in the habitat was examined, as well as their food preference, the effect of food and the daily rhythm of activity, and population density. The study was conducted in the summer and early autumn periods in four years (1998–2002) in a mixed coniferous forest Leucobryo-Pinetum (Matuszkiewicz, 1962) located in central Poland (52°20’N, 27°25’E). The insects were captured in baited traps functioning as Barber’s traps do. They were marked by clipping wing covers (based on the CMR technique). In total, about 31 000 individuals were caught and marked. It has been found that among faeces of different mammals, the faeces of forest rodents are the most attractive food for dung beetles. Food stimulates movements of beetles towards its source (foraging activity). The peak activity coincides with the afternoon hours (5.43 individuals per trap, on average, P ≤ 0.0001 as compared with the other periods of the day and night). There were years with a high number of captures (11.9 individuals per trap per day) and a low searching activity, and years with a low number of captures (5.06 individuals per trap per day) and a high searching activity. To compare differences in the number of beetles captured in pitfall traps with their genuine numbers in the habitat, the method of square sampling was used for evaluating their density (1.13 × 103 individuals per ha). There were days when the locomotor activity of the dung beetles was low and days when the number of captured beetles exceeded several times their genuine density on the area of 1 ha.