The influence of the dung beetle Copris incertus on dung removal and gastrointestinal nematode density on pasture.

Gastrointestinal nematodes (GIN) are considered of major importance by livestock farmers, with burdens limiting production. Dung beetles have been reported to reduce GIN numbers by direct damage during ingestion, increasing aeration and desiccation in the dung pat, and moving dung deeper into the soil. This study investigates the impact of differing densities of the paracoprid dung beetle, Copris incertus, on GIN across different seasons in New Zealand. Treatments of different dung beetle abundances (Control, Low, Medium and High) were applied in field enclosures during four-week periods in spring, summer and autumn. A Natural treatment, with no enclosure to allow unrestricted colonisation of the dung, was included in summer and autumn. Dung pats containing nematode eggs were applied to all plots. In both spring and autumn there was increased dung removal at the highest dung beetle abundances. In spring the increased removal of dung from the soil surface was associated with more buried dung balls and an increase in the number of infective larvae stage 3 (L3) numbers in the herbage in the High dung beetle treatment. There was no evidence that Copris incertus reduced nematode larval numbers on pasture, regardless of beetle densities.