This may sound like an unlikely rallying call, but in the realm of soil health, this particular group of insects can provide profound benefits, including improving soil structure and fertility, reducing the parasitic burden in livestock, and increasing carbon sequestration. They also provide an important food source for birds, such as waders. Like so many of our native flora and fauna, dung beetles are in decline, largely due to modern agricultural practices.
What are dung beetles?
Dung beetles are a diverse group of invertebrates whose existence is entirely dependent on the dung of herbivores for their food source and in most cases also their habitat. In the UK, there are 60 known species, falling in to three distinct groups:
- Aphodiines (‘dwellers’ and ‘stealers’)
- Onthophagus (‘tunnellers’)
- Geotrupes (‘tunnellers’)
Why are they important?
Biodiversity, soil structure & fertility
We all know that animal dung provides an important source of nutrients and organic matter when added to the soil, but this is only the case when it decomposes. When manure lands on grass and remains there, it kills the grass by preventing light and air from reaching it, and gradually releases methane to the atmosphere. To be of benefit to the soil, manure needs to be quickly broken down and dragged underground. In healthy, biodiverse soil, this service is provided by a whole host of bacteria, fungi and invertebrates, including dung beetles. The proliferation of these small organisms is beneficial of course as a food source for birds and larger organisms all the way up the food chain.
“Bioturbation is defined as the reworking of soils and sediments by animals or plants. These include burrowing, ingestion, and defecation of sediment grains. Bioturbating activities have a profound effect on the environment and are thought to be a primary driver of biodiversity.”
Reducing the parasitic burden in livestock
By quickly removing dung from pasture, dung beetles help to disrupt the lifecycle of pests such as parasites and flies, which could otherwise proliferate, with negative impacts on animal welfare, and requiring expensive and environmentally harmful treatments.
Dung that is not broken down and buried underground, remains on the surface and forms a hard crust. This crust creates an anaerobic (without oxygen) environment that promotes fermentation, resulting in the release of methane gas to the atmosphere. When it is buried, not only is fermentation prevented, but the numerous lifeforms that it benefits proliferate underground, feeding plants that then draw more carbon dioxide from the air, and continuing the carbon cycle.
Why are they in decline and what can we do about it?
Several modern livestock management practices have contributed to the decline of dung beetles. Principle among these are the overwintering of animals (mostly cattle) indoors, feeding them high grain, low fibre diets, and the routine administration of worming products.
Keeping grazing animals on pasture all year round
Sheep are not normally kept indoors over winter, so at Carbeth, we do have dung on some pastures all year round. The addition of small numbers of other grazing animals, such as cattle, may help to improve the diversity of dung available, and therefore the number of species of dung beetles that can be supported on the farm.
The excess of grain and lack of dietary fibre is another problem that applies mostly to cattle, but we can still aim to reduce the supplementary feed we give to our sheep, replacing it as much as possible with home grown forage. This should improve the natural composition of their dung, benefiting dung beetles, as well as reducing our costs and carbon footprint.
Reducing the use of worming products
The drugs that are used to treat parasite infestations in animals are excreted in their dung and urine, and are toxic to other invertebrates that may come in to contact with them. The welfare of our animals is our first consideration and it is essential that they be treated appropriately against parasites, but there are many steps we can take to reduce our use of these treatments.
- Genetics – worm resistance is an important consideration when choosing which animals to breed from.
- Prevention – maintaining healthy animals and vaccinating where appropriate, helps their immune systems to be naturally resistant to parasites. Other prevention methods include grazing on longer grass (since worm eggs are mostly found at the base of the stalks), and incorporating herbs and grasses with natural anti-parasitic properties in to our pasture. These include chicory, plantain, sainfoin and birdsfoot trefoil.
- Assessment – rather than routinely administering anti-parasitic products, we conduct faecal egg counts to establish if the treatment is really necessary. As well as reducing the volume of toxic products that end up on our pastures, this also saves money and reduced the likelihood of the parasites acquiring resistance to the products. Understanding the parasitic burdens of each field can also be an important tool in reducing the risk to our animals. For example, we can avoid grazing younger animals, who have lower natural immunity, on high risk fields.
- Treatment – where treatment is necessary, it is important that the dosing should be correct. Over dosing is not only expensive, but results in a higher level of product being excreted. Under dosing risks being ineffective and promoting drug resistance.