Contribution of the timing of the successive waves of insect colonisation to dung removal in a grazed agro-ecosystem

• We investigate in the field the timing effect of colonisation waves on dung removal.
• We test for the effects of dung beetle activity on the variability of removal of dung pats.
• Dung removal is decreased in the absence of the first week colonisers in comparison to freely colonised dung pats.
• We reveal the antagonistic effects between the first week colonisers and the second week ones.

Across the globe and in a multitude of environments, the preservation of the quality of pastures is partly due to the coprophilous communities that degrade dung. They contribute to ecological functions such as nutrient recycling and soil aeration, and thus primary production. The current experiment used exclusion mesh during the two first weeks after the deposition of cattle dung pats to investigate the functional effects of the timing of colonisation by coprophilous insects (both coprophages and predators) on the degradation of pats. The first week of colonisation was crucial to quick dung removal, despite the high heterogeneity of colonisation of such patchy and ephemeral resource. The second week reinforced the role of earlier colonisers by showing antagonistic effects that were probably due to the top-down regulation of dung removers by predators and parasites in grazed ecosystems.