Exciting new opportunity for biological control of wasps

By Ronny Groenteman, Landcare research, Lincoln

Wasps are now widespread throughout New Zealand and in some habitats they are among the most common insects encountered. As a result, wasps have detrimental impacts on native ecosystems, economic impacts on our primary industries, give rise to human health issues, and cause disruption to recreational activities.

Current control options do not provide satisfactory relief, and biological control is thought to be a useful option to explore. When successful, biological control provides long-term, cost-effective solution, covering large scales and difficult terrains. This is especially important when the pest is as widespread as wasps are in natural habitats that are vast and impractical to cover by more intensive control methods.

Biological control against wasps in New Zealand was attempted in the late 1980s, but the first agents to be introduced either failed to establish, or produced insufficient levels of control. Although there were other potential agents to explore, the programme was abruptly discontinued.

At Landcare Research we have recently been thinking that the time was right for re-visiting the programme for biological control of wasps. Not surprisingly then, we were excited to hear about the serendipitous discovery of a seemingly devastating mite in wasp nests in New Zealand.

The mite was discovered by Dr Bob Brown, at the time a PhD student. Bob was working on chemical ecology of wasps, as part of a collaboration between Auckland University and Plant & Food Research at Lincoln. He was seriously upset when some wasp colonies he collected for his study started collapsing in the lab. When he examined the wasps under a microscope, he discovered they were heavily infested with mites. The mites were not easy to identify, and are likely to be a new, yet un-described species. An association between such mites and Vespula wasps has never been recorded anywhere.

Who are these mites? Where have they come from? How long have they been in New Zealand? Are they widespread? Do they actually harm wasps, or are they simply hitching a ride? Can they cause wasps colonies to collapse out in the wild as they seem to have done in the lab? Do they only use wasps as their host, or can they transfer to other insects (honeybees, bumble bees, native bees)? These are only some of the important questions we need to explore in order to determine if these mites can be suitable biocontrol agents against wasps. Luckily now that Bob had completed his PhD on wasp chemical ecology, he no longer views the mites as a nuisance, and is excited about the opportunity to explore their beneficial potential.

To be able to assess the mite as a biocontrol agent, the recently-formed community group V-BAG (Vespula Biocontrol Action Group) will be applying to MPI’s Sustainable Farming Fund in November 2013. V-BAG is based at the Top of the South, and currently includes mainly conservation and restoration volunteer groups, along with Nelson and Central Otago winegrowers. Soon, we hope to see more industries (forestry, apiarists) and more regions represented. Sustainable Farming Fund provides grants for projects of up to thre years, and we hope to get this project funded to commence in the coming financial year (July 2014).

We are currently seeking to increase the support base for this project. So, if you would like to find out more please get in touch on: (03) 321 9904 or This e-mail address is being protected from spambots. You need JavaScript enabled to view it .


Auckland Biosecurity forum a success

Contributed by Jenny Taylor, The New Zealand Institute of Agricultural and Horticultural Science

The New Zealand Institute of Agricultural and Horticultural Science held a successful Biosecurity Forum at the University of Auckland in early July with an attendance of 113 people from a range of organisations. The mix of speakers and different viewpoints on biosecurity that were presented did expand our understanding of this topic. Interesting that we did not disagree on the importance of biosecurity but yet there is still room to sort out how best we approach it. The forum did meet the aim of bringing different groups together and promoting discussion and we received feedback that as an independent organisation, NZIAHS was playing a useful role here. "

NZIAHS represents over 600 members covering all aspects of the primary sector including crown research institutes, universities, primary industry companies involved with the meat, wool, dairy, fertiliser and horticultural sectors.

More detail will be available at the NIAHS website at:


Something fishy about sheep leg

Questions were asked in Parliament in early September about the testing of a possible animal part which arrived in New Zealand with a shipment of palm kernel feed.

The limb was discovered in May on a Bay of Plenty dairy farm. It was originally identified as most likely being that of a small deer or goat species not present in New Zealand.

By June 26, MPI announced, following DNA testing by Landcare Research, it was confident the leg was from a New Zealand sheep despite of one of the four DNA samples indicating it was from a snapper.

Science team leader at Landcare Research, Lynley Hayes said Landcare Research did not extract the DNA but only tested the material that was sent.
"As you can see from the 99 per cent score, we are confident that that was most likely snapper.”

"How that vial came to be, and was sent to us, is something that we don't know - we just tested what we were given," Ms Hayes said.
Labour spokesman for primary industries, biosecurity and food safety Damien O'Connor, believes human error may have been at play prompting him to bring the matter to the attention of Parliament

Adapted from an article published by Fairfax media on September 3, 2013


Pest seeds spilled

More than 2000 seeds of a feared invasive weed have spilt from the back of a truck making the 40-kilometre journey from Ashburton to Methven.

The seeds of black grass, or meadow foxtail, an invader of winter crops in Britain and Europe, were found in a 16.3-tonne consignment of red fescue grass seed imported from Denmark and were being taken to a containment centre.

But according to the Ministry for Primary Industries, the importer did not follow instructions to keep the load safe.

Now Foundation for Arable Research scientists and ministry, Federated Farmers and Environment Canterbury staff are working to identify where the seed may have spilt.

Black grass is resistant to many herbicides and is difficult to control in several crops. It competes for nutrients, light, water and space, out-competing crops and reducing yields.

However, the ministry believes only a few seeds will germinate.

MPI response manager David Yard said the seeds were "fairly immature".

"There might be three or four germinate in the first year and one or two in the second year."

He estimated 28 kilograms of red fescue had spilt during the trip. Included in that would have been about 2100 black grass seeds – enough to fill an eggcup.

He would not name the importer, who was under investigation, and prosecution was a possibility.

MPI would also be taking up the matter of the contaminated cargo with Danish authorities. The red fescue consignment had been rejected and would shortly be shipped back to Denmark.

The spill had occurred in July, a month after the consignment arrived at Lyttelton. MPI was alerting the public now as a possible germination date approached.

FAR chief executive Nick Pyke said that given the potential economic impact of the weed establishing itself, it was vital all reasonable steps were taken to prevent this.

"Early reporting is vital. Farmers can assist by keeping an eye out for any sign of the pest and if found report it immediately," he said.

The likely period to see the black grass would be November to April. The seed heads are usually reddish-purple in colour, giving the appearance from a distance of black grass.

Information on the plant and a photograph is available at:

Adapted from an article in The Press by John Morgan on September 5, 2013.


What to do about Gazanias

By Susanne Govella, Greater Wellington Regional Council

The pest plant biosecurity team in Wellington are quite excited about a control trial of Gazania spp. we will be carrying out on Wellington’s west coast during this coming season.

Gazania linearis and G. rigens are two species of garden plants commonly sold in New Zealand and Australia. The bright colours of their flower heads along with their ability to tolerate dry conditions and poor soils have made them popular among gardeners.

Gazanias are native to South Africa where they can be found from low altitude sandy soils to alpine meadows. Species of Gazania hybridise freely when possible, making identification of any Gazania challenging.

Outside their natural range, Gazanias are known to invade agricultural areas and roadsides and can rapidly out-compete native plants, leading to a decline in biodiversity. Their tolerance of dry conditions and poor soils means that Gazanias pose a significant risk to coastal plant communities in New Zealand. It is for this reason that Gazanias have been classified as a “red alert” species in several coastal management plants both in New Zealand and Australia.

The recommended control option for control of Gazanias has typically involved using the herbicide glyphosate, however the efficiency of this control option has now been questioned following a failed control operation in 2011 on Wellington’s south coast.

GWRC Biosecurity Department has been approached by Wellington City Council and Take Care community groups for advice regarding control of Gazanias in coastal ecosystems, following failed control operations and an increase of Gazania plants found in areas previously occupied by other pest plant species that had been successfully controlled.

Although herbicide trials for control of Gazania are currently being carried out by the Riverland Winegrape Growers Association in Loxton, Australia, the herbicides of choice, Amitrole and Diquat, are not recommended for use in fragile ecosystems such as coastal dunes in New Zealand. Therefore the Biosecurity Department plans to undertake control trials aimed at providing a reliable control method for use in fragile coastal ecosystems in the Wellington region.

The aim of this project is to carry-out a spray trial comparing the performance of four agrichemicals (Glyphosate, Grazon, Tordon XT and Versatill,) as a means of controlling Gazania coastal dune ecosystems. By the end of this trial we hope to be able to recommend either a proven control method for Gazanias in coastal dune ecosystems, or further research into developing reliable control methods for Gazanias.

The trial is an interdepartmental collaboration to assure it meets the scientific standards required by our new work procedures. It has been prepared by Nikki McArthur, Environmental science department, Darryl Kee and Susanne Govella Biosecurity pest plants at Greater Wellington Regional Council.

We are looking forward to report back our results after the completion of the trial in September 2014.




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