Landcare Tasmania recently surveyed 4 farms in and around the Coal Valley to see how dung beetles are going in the area.
Australia used to have dung beetles that were very good at burying the dung of big animals. The problem is - they went extinct with the megafauna... So when Europeans brought big animals like cattle, horses and sheep to Australia, there was a problem - too much dung lying around on the surface.
This dung washed into our rivers, polluting them, and bred huge populations of flies.
With the introduction of dung beetles, they have proven to be great 'ecosystem engineers' that bury cow, horse and sheep poo! This keeps it out of our waterways, makes the paddocks more healthy, helps the grass grow faster, and destroys gut worms that would otherwise infect the livestock. Burying all that dung has brought down fly numbers, made the soil more fertile, allowed the rain to soak into pasture better, and brought down the amount of dung that pollutes our streams and rivers -all adding to farm productivity and ecosystem health.
Image: Dung Beetle Cards!
Since the introduction of dung beetles, with scientist trying to figure out which dung beetles are best for burying problematic dung, a dozen types have been introduced to Tasmania. These dung beetle surveys help see how the beetles are going in the Coal Valley.
The Surveys - What We Found
Happily, we found good numbers of both Onthophagus binodis and Euoniticellus fulvus, getting lots of cow dung buried! We also found high numbers of Aphodius fimetarius. Fimetarius is not a true dung beetle, and sadly it doesn't actually bury dung. It still does do some good work though, by shredding the dung up so the grass can grow through.
Image: Onthophagus binodis ID Sheets by Russ Barrow
We also found a few Acrossidius tasmaniae, commonly known as Cockchafers. Unfortunately, this native beetle eats grass roots, damaging pasture.
Image: Acrossidius tasmaniae from the Atlas of Living Australia
We found a few pleasant surprises, too! We found one Blue Bomber (Geotrupes spiniger)! This is unusual, because they are mostly active in the autumn. It seems this fellow was either very confused, or an innovator, trying out a new time of year!
Another lovely surprise was finding good numbers of the beautiful little native dung beetle Onthophagus posticus on one property. Usually these beetles keep to native animal poo, so it was interesting to see them getting stuck into the cow dung.
The survey shows us that we have pretty good numbers of small dung beetles active in summer in and around the Coal River Valley. However, we still have a long way to go before we have made the most of the possible benefits of Dung Beetles in the area! There are still very few beetles active over winter and in the early spring.
It would also be beneficial to have some larger, deep tunnelling, summer-active beetles. Onthophagus binodis and Euoniticellus fulvus bury dung to about 10-15cm depth. Many larger deep tunnelling dung beetles bury dung 50-70cm under the ground! Having dung buried deeper down encourages deeper root growth, pumping carbon and nutrients further down there and gradually increasing the thickness of the more horizon of the soil.
The Dung Beetle Ecosystem Engineers Project is soon to release a list of 10 more dung beetles to be brought into Australia. Hopefully at least a couple of those will be useful for us down here in Southern Tasmania.
This program is supported by the Tasmanian Government's Landcare Action Grants.
