Celebrate the dung beetles

Encouraging Dung Beetles on Horse Properties

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Encouraging dung beetles in horse properties:

Dung beetles are very cool creatures! They eat and bury your horse or cattle’s poo, control insects and parasites, de-compact soil, cycle nutrients and hydrate your pasture – and they do it all for free.

Dung beetle behaviour has fascinated humans for thousands of years, including the ancient Egyptians, who accurately documented that dung beetles’ ball rolling is influenced by the sun.

We now know some species of dung beetles even use the moon and galaxies to navigate and roll their manure in straight lines! They are currently the only known non-human animal to orient themselves using the Milky Way.

If you have horses and manage them mostly on pasture, you want dung beetles! If you already have them on your property you undoubtedly noticed they are very active around the end of Spring and Summer.

While Summer is officially over, dung beetles are still active until the end of Autumn and there are also some species that are Winter-active.

Having dung beetles around as long as possible and throughout the year would be an ideal situation on all farms and horse properties, but it requires some thoughtful management.

In particular, this means we should try to manage our land and horse-worming regime all-year-round to benefit from these little creatures. In the following article, we will discuss dung beetles in Australia, how they specifically benefit horse properties and how we can keep them happy.

Dung beetles in Australia

Australia has more than 500 species of native dung beetles and 23 species of dung beetles introduced from Hawaii, Africa and southern Europe. The introduced dung beetles are very useful in Australia’s pastoral regions. Where they are well established, these dung beetles bury large volumes of cattle and horse dung. Some species can remove a pat in less than 24 hrs!

The burying of dung underground by beetles has many benefits for the soil, water and pasture, as well being a form of biological control for flies and parasitic worms – helping to protect our horses.

The Dung Beetle Project

Most Australian native dung beetle species eat marsupial dung (from kangaroos and wallabies) and don’t process the moist dung of domestic farm animals very well. Only a few native species can consume the moister dung of horses, sheep and cattle. Thus, as part of a larger Dung Beetle Project, about 40 species of exotic dung beetles have, so far, been introduced to break down the manures of farmed animals and, of the 40, just 23 have been successful.

The Australian Dung Beetle Project (1965-1985), conceived and led by Dr George Bornemissza of the Commonwealth Scientific and Industrial Research Organisation (CSIRO), was an international scientific research and biological control project, with the primary goal to control the polluting effects of cattle dung.

To see all the species that were released, click here.

And to find out about the latest 2020 arrival… click here.

What species?

Climatic and geographic limitations require 6-10 species be colonised on farms to get year-round activity in dung removal. Most dung beetle activity takes place in Spring, Summer and Autumn but, recently, Winter-active species have been identified (Bubas bison and Geotrupes spiniger or Blue dung beetle) for introduction to farm.

These Winter-active beetles are mainly found in parts of South Australia, Victoria, New South Wales and Western Australia. However, researchers are working on a new project to import more Winter-active species, but this will take some time, due to our strict quarantine policy.

Besides beetles, we could also benefit from earthworms as they are at their most active during the Winter – converting organic material into plant food, and aerating the soil.

A busy life

The life cycle of dung beetles sees beetles actively consuming dung and burying it for 2-3 months followed by a hibernation period. Only when similar seasonal conditions prevail do the beetles once again become active, coming out of dormancy from the eggs that were laid up to 300mm in the soil during the previous active season.

Depending on species, some dung beetles will go through 1-2 life cycles during an active season. Each mature female beetle will lay 60-80 eggs in a season, thereby increasing population by this factor in one generation. Dung beetles are known to spread up to 2km per year if unimpeded by bush or barrier, and will diminish in density for a period of time after their release before consolidating their population.

Dung beetles on horse properties

Dung beetles are very beneficial to our pastures, our horses and ourselves.

For us horse owners, they mean less cleaning paddocks and poo shoveling, and great soil development without cost or effort! They also help control fly and parasitic worm populations, which is superb news for our horses.

So, if you have dung beetles, take good care of them and, if you don’t think you have them, chances are you probably do have them in the ground, but you need to create the right conditions for them to establish and thrive (keep reading).

It is also possible to acquire dung beetles from organisations and institutions in your region that you can release. Check to make sure they suit your soil conditions as they are very fussy about the type of soil.

Did you know? A dung beetle can bury dung 250 times heavier than itself in one night. There is one species – Onthophagus taurus – that can pull a load 1,141 times its own weight! It’s considered the strongest insect in the world! Most dung beetles search for dung using their sensitive sense of smell. Some of the smaller species simply attach themselves to the dung-providers and wait for their reward to be delivered!

Taking care of dung beetles

Dung beetles help break down poo while transporting it underground, which helps with soil decompaction and fixing nitrogen. But, be aware that if your pastures are severely compacted, even dung beetles cannot do the work for you.

If the soil is too hard, they will die because the spikes on their legs get eroded and, without them, they cannot bury themselves into the ground.

So, if you find that you don’t have beetles or you have very small amounts, you may need to help them with some soil development strategies like  de-compacting using Keyline ploughing,  composting and mulching.

Dung beetles also require fresh dung, so it’s important you don’t remove all the good, fresh manure from pastures and yards. Only remove the older pats that have been left to decomposed for at least 3-4 days, and you can see the pat is all broken down, spread and only larger fibre components are visible. By this stage, they also have a greyish colour.

Care with wormers and other chemicals

Many treatments for the control of cattle or horse parasites and pests have negative effects on dung beetle survival, breeding capacity and activity.

A thorough review of the effect of macrocyclic lactone (ML) drenches on dung beetles has shown toxicity rankings against non-target species was greatest for doramectin, followed by ivermectin and eprinomectin, with moxidectin being significantly less toxic.

Ivermectin is a very effective anti-parasitic drug that has been used as a preventative in livestock since its discovery in 1981. Its use increased exponentially to become a standard drug in the treatment and prevention of common parasites, including in humans. While considered by the World Health Organization as an essential medication and proven very effective, its widespread use comes at a price.

The issue, researchers have found, is the ivermectin molecule can survive its journey through the animal and be excreted unchanged. Also, once on the ground, residues can remain active in animal dung for at least a month.

This means the drug hits the arthropod populations as hard as it does the parasites it is intended to prevent.

The ingestion of ivermectin affects even mature dung beetles, seriously compromising their mobility, orientation and reproductive capacities.

The findings contradict international veterinary manuals and yet, they offer a compelling explanation for the decline in dung beetle population levels reported in other research.

While invermectin may be harmful to beetles it is not to say you cannot use it, as many horse owners like them for the control of bots. You just have to be aware of the timing – either late Autumn (when it gets colder) or very early Spring before it warms up. This avoids the Summer period, which is when most dung beetles are active.

Other dewormers like fenbendazole and oxibendazole are also commonly used, but they are less toxic compared to invermectin or other avermectins.

Wormers with moxidectin aren’t as lethal to immature beetles and have a shorter time of toxicity (only three days after drenching). Choosing this drench will ensure management decisions for parasite control will have no effect on dung beetle activity. However, you will need to review the chemical used as resistance in horses is another factor you need to consider when choosing the type and brand of dewormer.

Before you take action and buy your dewormer, it’s advised you conduct a faecal egg count (FEC) for each horse on the property, which helps in identifying the severity of the worm burden. Faecal egg counts (FEC) of less than 200 eggs per gram is regarded as ‘low’ and no further action is required. So, often only a few horses require treatment. Remember though, an FEC won’t work for encysted worms, tapeworms or worms at the life-cycle stage where eggs are not being laid.

To ensure you don’t kill many dung beetles in your pasture, it’s generally advised to keep your horses for at least 3-7 days in a sacrifice area, central point or yards after drenching, so you can collect and dispose of the manure during this time. As mentioned earlier, avermectins (such as invermectin) may still be active for many weeks, but you will reduce some of the toxic effects.

Did you know? Many dung beetles, known as rollers, roll dung into round balls, which are used as a food source or as a chamber for their eggs. Others, known as tunnelers, bury the dung wherever they find it. A third group, the dwellers, neither roll nor burrow: they simply live in manure. Dung beetles can grow to 3cm long and 2cm wide. All the species belong to the superfamily Scarabaeoidea; most of them to the subfamilies Scarabaeinae and Aphodiinae of the family Scarabaeidae (scarab beetles). As most species of Scarabaeinae feed exclusively on faeces (some also on mushrooms, and decaying leaves and fruits), that subfamily is often dubbed true dung beetles. There are dung-feeding beetles which belong to other families, such as the Geotrupidae (the earth-boring dung beetle).

Pasture management

When horses graze, they are very selective. They can eat down some areas almost bare, while leaving other areas in which they dung and urinate untouched.

If these paddocks and pastures are not managed properly, you can get over-grazed and ‘horse-sick’ pastures with poor quality grasses, accumulation of weeds, compacted and eroded soils, manure build up and higher populations of parasites.

Horse-sick pastures may be more evident when there is insufficient land, but larger horse properties can also have these problems, despite their size.

These horse-sick pastures not only affect the health of your horse, but also negatively influence the shape of the land, and can reduce the value of your property or the adjacent land.

To manage both soil and parasites, pasture rotation, strip grazing and cross-grazing (alternating with livestock) are effective ways to reduce parasite survival.

Rotating horses to ‘fresh’ pastures ensures recovery of grazed pastures and allows you time to work on soil development (e.g. composting, mulching, keyline ploughing), which helps with keeping the soil healthy for your little soil workers – dung beetles.

As mentioned earlier, dung beetles cannot survive in severely compacted soils, so taking care of this problem is important for their longevity.

Understandably, we will never fully avoid compaction along boundaries, water and feeding points, but with timely grazing and moving animals frequently, this compaction is less severe and can be easily restored using mulching techniques, or just recovery time if you have healthy soils to start with.

Other management strategies

Another solution to minimise compaction in your pastures is to use tracks (laneways) and/or a sacrifice or central-point system that can take some of the regular congregating of animals.

As the word suggests, these are areas where you ‘sacrifice’ compaction for the benefit of pasture and plant growth in other parts of your property.

Such areas can provide a central space for loafing, watering, feeding or to remove horses from the pasture altogether to allow soil and plant recovery, or reduce your horses’ pasture intake.

The design of your sacrifice/central point will largely depend on the number of horses, space available and budget.

Footing and drainage

While you allow compaction to happen in these areas, it’s important you pay close attention to the drainage and footing to avoid mud build up, which can be very dangerous for you and your horses.

Consider the shape of the land, and review if you need to level and prepare this area in such away that it allows water to slowly drain, without causing quick run-off and erosion.

The sacrifice area will need to be fenced off and requires a border around the footing to avoid run-off. You can even build a (rock) rain garden that can take some of the extra run off water (See last month’s article).

There are many types of materials that can be used as footing and your choice will largely depend on your preferences, availability and budget.

River sand, pea rock gravel and wood chips are regularly used for their comfort and/or price, and can be applied to different areas.

You can also decide to use ground stabilising products, such as plastic pavers with a cell-like structure (honeycomb or diamond). Typically, sand or pea rock is used to fill the grid spaces, and this will allow water to pass through, without turning it into a muddy area. This system can be very useful for high impact areas, such as gateways, tracks and water points. However, it still needs to be managed and manure should be taken away regularly to avoid build up that can turn into a slurry.

The roll out

If you have horses and manage them mostly on pasture, you want dung beetles on your property!

They muck out your paddocks, build carbon, and increase the availability of nutrients and water.

Dung beetles, together with other soil workers, such as earthworms, fungi and bacteria, are all important for the health of our soils and pastures. We never feed plants directly – this happens through the process of breaking down organic matter, which is done by our soil workers.

Although they do all the work for free, we still need to remain involved, guiding the process in the right direction and creating conditions our soil workers thrive in.

This means we need to have an integrative approach for the management of our horses and our pasture. Selective worming, pasture rotation/resting and cross-grazing with livestock will all contribute to maintaining healthy soils, reducing parasite burden and resistance in horses.

A personal note

This year, I have been observing large quantities of dung beetles on our property in the New England region of New South Wales. In September 2015, my partner and I moved in to this 100-acre property but, it wasn’t until March 2016, that we stocked it with horses and cattle. When we did that, we saw Autumn dung beetles become immediately active.

Last year, before Spring, we boosted our soil using a biostimulant to increase nutrients and substrate for our soil workers, and this has been key to getting large activity from soil organisms and dung beetles this Spring and Summer!

On our property, we cell graze and rotate cattle and horses, focusing on allowing both soil and pasture to recover.

As an example, a cell that has been just been grazed may get 8-9 months recovery time before the horses return.

Only 50 to 60% of the horse manure is collected for composting and spot mulching compacted areas left in the cells (e.g. corners and fence lines). The remaining poo is left for dung beetles to break down.

In the peak of Summer if I collected horse poo in a wheelbarrow and tipped it out into areas where I did some mulching, I will have hundreds of different beetles at the bottom of my wheel barrow (I did return them to my soil and mulch).

Some of the species I was able to identify with the help of an entomologist from the University of New England were: Onitis pecuarius, Onthophagus binodis and Euoniticellus fulvus, so I have included some information about them.

Of these three species, the first two (bigger species) are most productive in making your poo disappear.

Poo is Cool

Believe it or not, it turns out poo is cool and dung beetles can be cute – even when standing on top of a stinking pile. When are beetles cute? When researchers decide to give them little green boots and test their poo-top dancing ability, all in the name of science! Yes, you heard right, little green boots…

Many species of boll-rolling dung beetles live in deserts, where the midday sun can heat the sand to temperatures of up to 60°C. For humans, this means serious discomfort and it’s no different for the little insects.

Dung beetles, it turns out, use the moist ball of dung as a refuge from the hot sand. The ball of dung can be several tens of degrees cooler than the sand so, by standing on top of it, they’re able to avoid getting fried.

The researchers discovered this by monitoring how many times dung beetles jump on top of their balls, given a certain ground temperature.

Below 50 degrees C, the beetles would simply push their balls in a straight line for 1.5m without stopping. But, above 50 degrees C, they would stop, jump on top of their dung and hang out for a bit. However, the researchers didn’t stop there; they wanted to know exactly what triggered this behaviour. And this is how researchers got to the tiny green beetle boots.

They had ‘beetle boots’ customised from dental silicon. These boots, which insulate the feet from the hot sand, were placed on the dung beetle to determine whether it was leg temperature or thorax (the part of the body of a mammal between the neck and the abdomen) temperature that was the thermoregulation trigger.

When the dung beetles wore their hipster-inspired leg wear, they were less likely to climb the ball of poop, even in hot temperatures!

Can you imagine being the scientist in charge of writing the grant application? “Um, we need the money to put little boots on some dung beetles to find out why they climb on their dung balls so often…” 

Check out their abstract here.

Mariette van den Berg, PhD, BAppSc (Hons), RAnNutr

Mariette van den Berg has a PhD in Equine Nutrition and Foraging Behaviour, is a RAnNutr equine nutritionist, a Certified Permaculture Designer and a dressage rider. She is the founder of MB Equine Services.

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