First releases of dung beetles
Published: 8 October 2013 - by Shaun Forgie
Dung beetles have been released on New Zealand farms following an exhaustive research and consultation process
Additional species of dung beetles have been released on New Zealand farms following an exhaustive research and consultation process.
By burying the dung of large grazing animals, dung beetles improve soil health and pasture productivity, reduce water and nutrient runoff, as well as the reinfection of livestock by parasitic worms. There are also human health benefits as dung is a habitat for flies which spread disease.
New Zealand has forest-dwelling native dung beetles that do not live in pasture. One exotic species, the Mexican Dung Beetle has become established here but only in the warmer climate at the top of the North Island.
Members of the Dung Beetle Release Strategy Group (DBRSG) were joined by representatives from local authorities and science staff from Landcare Research at the release of Onthophagus taurus and Onthophagus binodus on an organic farm in Gore followed by another property in Wairarapa.
The DBRS Group was established by a group of farmers and other interested parties in 2008 with the objective of importing and releasing dung beetles to assist with the removal of pastoral dung of agricultural livestock. As part of that process Landcare Research was contracted to supply science and technical support.
Permission to import and release 11 additional species of dung beetles was received from the Environmental Risk Management Authority (now EPA) in February 2011 and the beetles were initially held in containment at Landcare Research until given disease clearance by the Ministry for Primary Industries. Once released from containment in 2012 dung beetles were mass reared at both Landcare Research’s campuses in Lincoln and Tamaki. Some caged field trials were also been undertaken to test how the beetles might perform.
Dung beetles search out the faeces of animals which they use for food and reproduction. The species being introduced to New Zealand make tunnels in the soil beneath the faeces which they then bury to lay eggs in.
As the eggs hatch the grubs feed on the dung so they break it down and eventually turn it into a sawdust-like material that adds to the fertility of the soil structure while all the time getting rid of dung sitting on top of the ground.
As the eggs hatch the grubs feed on the dung to grow and develop into new adults. Remaining dung is utilised by earthworms and microorganisms in the soil that make the nutrients available for uptake by grass roots. Buried dung has been shown to increase earthworm numbers, increase soil fertility, improved soil structure, and increase the depth at which grass roots grow. Consequently grass becomes more drought tolerant. At the same time dung beetles get rid of dung sitting on top of the pasture reducing forage foul and forage avoidance around repugnant dung.
While dung decomposes naturally, intensive farming means large amounts of dung are dropped which can lead to environmental problems such as leaching of nutrients into waterways and reduced pasture production because of increased forage fouling.
More information on Dung Beetles: www.dungbeetle.org.nz