The seasonal biomass distribution of coprophagous beetles in fresh cow dung in a sub-mountain pasture

摘要

The biomass of coprophagous beetles (Scarabaeoidea, Hydrophilidae) in fresh cow dung was monitored on a sub-mountain dairy farm using pitfall traps baited with 1.5 litre of dung. Major peaks of beetle activity were in the May, July and August / September sampling periods (mean dry weight biomass (DW) was 3.05 g, 3.52 g and 6.03 g trap~(-1), respectively), while in June and October beetle activity was lower (mean DW trap~(-1): 0.47 g, 0.51 g, respectively). In all samples the greatest biomass belongedto the species without burial breeding behaviour, whereas the tunnelling beetles (that lay eggs in dung buried in the soil) formed a minor part of sampled biomass (4-18% of mean DW trap~(-1)). The highest impact of beetles on dung decomposition can be expected from August onwards due to larval feeding of the dung dweller Aphodius rufipes, contributing 80% of total DW biomass of the sample. The highest burial activity can be expected in May and in September due to breeding activity of Ontophagus spp. and Geotrupes spp., respectively.