AGRICULTURAL AND ENVIRONMENTAL BENEFITS OF DUNG BEETLES
The activity of dung beetles disturbs and buries fly breeding sites – aerating the anaerobic dung pad. Summer active beetles, during their feeding stage, desiccates the dung, destroying the moist humid environment necessary for fly and parasite breeding.
Dung burial recycles and releases nutrients locked up in the dung pad into the soil. If fresh dung is not rapidly incorporated into the soil, nitrogen, through ammonia volatilisation, is lost and nitrogen in the mineral nutrient that provides significant improvement in pasture quality, particularly in crude protein content, is largely wasted. Approximately 2% of cattle dung is composed of nitrogen, and that 80% of this nitrogen is lost if the pats dry in the sun before they are buried. It is estimated 27 kg of nitrogen is produced annually per animal, thus an estimated 21.6 kg is returned to soil by dung beetles.
The tunnelling action – whether to sub-soil depths or shallow tunnelling of summer-active species, increases water infiltration into soil and the buried organic matter enables increased moisture retention. Dung beetle activity enhanced soil water retention by 10% and promoted growth in plants subjected to drought conditions by 280%, relieving the impacts of water stress on plants. Mineralisation by soil biota and the transport of mineral nutrients to and within the plant is dependent upon adequate soil moisture.
Improved infiltration, especially during sudden rainfall events, reduces nutrient and sediment run-off and loss of topsoil. This not only reduces eutrophication potential of waterways but also reduces disease transmission by limiting the entry of parasite cysts into waterways.
Soil Structure and Fertility
The mechanical tunnelling action of dung beetles, the depth determined by the species, enables increased water infiltration. Plant roots are able to access moisture and nutrients from deeper in the soil profile. Dung beetles encourage the presence of earthworms, adding to the aerating effect, creating an aerobic growing environment for soil biota as well as plants.
Fodder is more palatable when dung pads are rapidly degraded, distributing rather than concentrating nutrients - cattle will not consume plant material that is fouled with dung, reducing the area of accessible pasture for consumption. Dung beetles distribute seeds in dung vertically and horizontally; buried seeds are protected from severe environmental conditions, predators and pathogens. Seeds thus interred in shallow brood tunnels are ideally located for germination when opening rains moisten their organic seed bed. Increased pasture productivity (increased biomass and extended growing season - due to improved soil moisture retention) leads to increased profitability.
The Economic Value of Ecological Services Provided by Insects Losey, J. E. and Mace, V. BioScience 56(4):311-323. 2006
The Australian dung beetle project 1965–75. Bornemissza, G.F. 1976, Australian Meat Research Committee Review 30:1–30.
Bioscan: Entomology in Schools Allen, J.F., St Claire Baker, P., Dadour, I.R. 1995