Carbon Neutral: The Failure of Dung Beetles (Coleoptera: Scarabaeidae) to Affect Dung-Generated Greenhouse Gases in the Pasture

Research suggests dung beetles can churn, aerate, and desiccate dung in ways that influence the dung and soil microbes producing greenhouse gases (GHGs). We examined the impacts of the tunneling beetle, Onthophagus taurus (Schreber), and the dwelling beetle, Labarrus pseudolividus (Balthasar), on the carbon dioxide (CO(2)), methane (CH(4)), and nitrous oxide (N(2)O) emitted from pasture-laid bovine dung as well as their sum-total (CO(2) + CH(4) + N(2)O) effect on global warming, or their carbon dioxide equivalent (CO(2)e). Despite dung beetles potential effects on CH(4) and N(2)O, the existing literature shows no ultimate CO(2)e reductions. We hypothesized that more dung beetles would degrade pats faster and reduce CO(2)e, and so we increased the average dung beetle biomass per dung volume 6.22× above previously published records, and visually documented any dung damage. However, the time effects were 2–5× greater for any GHG and CO(2)e (E = 0.27–0.77) than dung beetle effects alone (E = 0.09–0.24). This suggests that dung beetle communities cannot adequately reduce GHGs unless they can accelerate dung decomposition faster than time alone.