The following Q&A was published on the old B+LNZ in October 2013. The website has been recently been replaced so I thought it useful to republish the Q&A here as a number of blogs are linked to it. This Q&A was prepared by Brigid Feely (To Be Frank Copywriters).
Dung beetles: Some common questions
Dung beetles are the agricultural curiosity story of the moment, following the release late last month of 400 beetles onto an organic dairy farm near Gore (26 September) and a second release in the Wairarapa earlier this month (8 October). Below is a quick Q&A, answering some of the questions around how these insects work and the benefits they offer.
You will find everything you want to know about dung beetles – including research papers and video links – on the Dung Beetle Release Strategy Group’s (DBRSG) website.
Q How exactly do dung beetles work?
A They search out the dung of animals and use it for food and reproduction. The species being introduced to New Zealand utilise only the dung of grazing livestock animals. They are “tunnellers”, making tunnels in the soil beneath fresh dung pats, which they then bury to lay eggs in. As the eggs hatch, the grubs feed on the dung, before turning into new adults and emerge from the soil to repeat the cycle. When a healthy population of beetles is established, they can process a fresh dung pat in 48 hours.
Q Why have 11 species been imported?
A Dung is produced night and day and the climatic conditions across New Zealand vary considerably. Some species of dung beetle are active at night while others are daytime workers. Additionally, some species are active during winter and others in spring, summer and autumn. So, the idea is that there are one or two species present in any given area, working 24 hours a day, throughout the year.
Q Does New Zealand have any species of dung beetle already?
A Three exotic dung beetle species already live in New Zealand, mainly in the North Island. These species have a long history in New Zealand – two of them have been in the country since about 1880. They are not considered a health risk and are not a threat to New Zealand’s environment, given they are restricted to dung in livestock pastures. The existing species are beneficial in terms of burying dung, however, they are not abundant enough, too small in size, or not active during enough of the year to make a noticeable impact. There are also native dung beetles, though these are all flightless and live mainly in native bush and forest habitats, seldom venturing into livestock pasture. Equally, the imported dung beetles will not venture into native forest – as there is no livestock dung to feed on – so there is no risk they will displace the native population.
Q Where have the beetles been imported from?
A Most of the 11 imported species are coming from Australia, where they were previously imported from southern Europe and South Africa – countries with climatic conditions similar to New Zealand.
Q Have the beetles been successfully introduced to any other agricultural countries?
A Australia has introduced more than 50 types of dung beetle during the past 50 years, with great success (although not all 50 species have established). Australian farmers are aware of the benefits provided by dung beetles to their farms, and are increasingly moving to drench types which do not impact negatively on the beetles in an effort to enhance the populations for maximum impact. Watch a short video clip, where Landcare Research Scientist Shaun Forgie visits Australia and talks to dung beetle experts about the beetles’ successful introduction.
Q What has happened so far?
A The Environmental Protection Authority (EPA, formerly known as the Environmental Risk Management Authority) approved the importation and release of the beetles in February 2011. Six species of beetles have been imported into containment at Landcare Research, where they have undergone a comprehensive disease screening process. Four species have since been released from containment for mass rearing and some caged field trials have also been undertaken. On 26 September, two species (Onthophagus taurus and Onthophagus binodis) were released on the Gore property, then two weeks later there was another release in the Wairarapa.
Q What will happen next?
A Alongside ongoing monitoring of the release sites, mass rearing of dung beetles is currently underway. The DBRSG is in the initial stages of setting up a web-based system, so farmers will be able to click on their geographic location and find out which beetles are suitable and available. It is not yet clear how releases of dung beetles will be offered and made available to the wider farmer community, but you can be added to a DBRSG waiting list to be kept abreast of progress.
Q How long until dung beetles establish themselves in New Zealand?
A Once healthy population numbers have been achieved on the farms they are released on, beetles will likely spread at a rate of about one kilometre per year. It is anticipated it will take many years for dung beetles to become established and abundant across all of New Zealand. The DBRSG website includes details on how to prepare for and enhance dung beetle populations on your property.
Q What are the risks? What are the benefits?
A The following is a summary of the benefits and risks to New Zealand sheep and beef farmers.
The benefits :
- Improved soil health and reduced runoff
- Increased pasture productivity
- Reduced infection of livestock by parasitic worms
- Reduced pasture pests and human disease
- Reduced greenhouse gas emissions
- Economic benefits, through reduced forage fouling and improved sustainable recycling of nutrients present in dung
The risks, the EPA assessed three potential environmental risks:
- Tunnelling of the beetles would lead to contamination of groundwater
- The introduced beetles could displace native beetles
- The beetle could become a vector for both livestock and human diseases and parasites.
EPA found all risks to be negligible, as supported by extensive internal and external reviews and testing
[Sources: Dung Beetle Release Strategy Group (DBRSG); Shaun Forgie, Scientist with Landcare Research; and Environmental Protection Authority.]
To join the dung beetle release waiting list or for more information on dung beetles, including research papers and videos, see the dung beetle release strategy group website