Dung beetles reduce livestock gastrointestinal parasite availability on pasture

Anthelmintics are widely used to control gastrointestinal parasites of livestock. However, the residues of these compounds, particularly the macrocyclic lactones, are excreted largely unmetabolised in faeces, where they may have toxic effects on dung-colonising insects. Impoverishment of the coprophagous beetle community impairs the process of dung recycling and, as a result, may enhance the persistence of dung-dwelling helminth parasitic stages. To test this possibility, a large-scale field trial was conducted in south-west England. The availability of infective parasite helminth larvae (L3) was investigated on the herbage around 240 artificial 1 kg dung pats that had been constructed from the faeces of beef cattle with naturally acquired strongyle infections. Herbage up to 15 cm surrounding each pat was sampled at 2, 4, 6, 8 and 10 weeks after deposition. Pats were subject to enhanced, natural or no dung beetle colonisation and uncontrolled or enhanced rainfall. Under uncontrolled rai...