Wiping out invasive wasps a 'critical issue' for New Zealand's environment

7 November 2016

Nelson wasp

A pest control method inspired by Greek mythology is one of the latest weapons being developed in New Zealand's war on invasive wasps.

Professor Phil Lester of Victoria University spoke at Nelson Marlborough Institute of Technology on Tuesday night about a research project he is leading aimed at wiping out wasp populations.

Lester, an expert in insect ecology, said it was appropriate that he was giving the talk in Nelson, which he said was the "wasp capital of New Zealand".

He said the German and common wasp have been wreaking havoc on New Zealand's native birds, insects and other wildlife since they were accidentally introduced in the 1940s and 1970s respectively.

They are most prevalent in beech forest where they feed on honeydew, a sugar-rich liquid secreted by aphids and a popular food source for birds, lizards and insects. But they have also caused major problems in residential areas and tourist hot spots like Abel Tasman and Nelson Lakes national parks.

Pest wasps also cost the country an estimated $130 million a year, impacting on farming, beekeeping, forestry and tourism.

"Certainly these wasps are one of the critical issues in New Zealand," Lester said, "especially around your neck of the woods."

Lester said research, funded by the Government as one of its National Science Challenges, was underway into four new pest control methods for the wasps.

One of the methods being investigated was called "the Trojan female technique", inspired by the Greek myth about the Trojan Horse.

It works by raising, and introducing into the wild, large populations of female wasps with mutations in their mitochondrial DNA, which might render their offspring sterile.

The other studies were looking at manipulating wasp behaviour using pheromones; using mites to deliver harmful pathogens into wasp nests; and RNA interference, also known as gene silencing, which Lester described as the "next generation of insecticides".

The research project was expected to take close to 10 years, Lester said.

In the meantime, he recommended that people used the protein-based bait, Vespex, developed by Nelson man Richard Toft, to reduce wasp populations in residential areas.

"If streets in Nelson get together and think, 'Let's get a program together' ... you'll be able to largely control wasps in your population with [Vespex]," he said.

The Department of Conservation has had success using Vespex, reducing wasp populations in parts of Abel Tasman National Park by 98 per cent.

In December, Nelson-based company Merchento announced the release of Vespex for public use.

Lester came to Nelson through the NZ Biological Heritage Challenge and his visit was supported by the Nelson Science Society.

- Stuff

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PhD student a finalist for this year's Wellingtonian of the Year awards

19 October 2016

A huge congratulations to Victor Anton for being announced as one of this year's finalists for the Wellingtonian of the Year awards in the Environment category.


Victor is a PhD student in the School of Biological Sciences at Victoria University investigating the impacts of predators on native biodiversity in urban areas.

To carry out his research, he has placed motion-activated cameras in Wellington locations to capture images of animals, and asked members of the public to then identify them online.

The project, in its second year, has so far collected over 160,000 photos.

“People have been really responsive, and most importantly the results appear reliable. When we compared experts with other volunteers and how accurately both groups were able to identify species from photos there wasn’t any meaningful difference. Each image is checked by at least two different people, this helps correct for small mistakes, like clicking the wrong button.

“The benefits of citizen science with this type of research are not just the ability to categorise data faster, it’s also about getting people involved—the more you involve them the more they care, and the more they learn about the species around them. People have been surprised to see rabbits in their garden, and other animals they didn’t know were living around them.”

Over the course of the year, motion-sensitive cameras were placed in approximately 50 green areas around Wellington, such as parks and reserves. Each area was recorded for one month per season to allow the researchers to understand how changing weather and seasons affected the biodiversity in these areas. An additional 20 cameras were placed in residential backyards and recorded year-round.

“We chose these based on criteria such as size, and connectedness to other green spaces—both of these factors are important for whether the space will support native birds, such as kākā, and they also influence the presence of pests,” says Victor.

Victor’s supervisor, Dr Heiko Wittmer, says: “This project is one of many examples of how research conducted at Victoria aims to improve biodiversity conservation in urban environments. Victor’s results will be vital for local constituents and to help the Wellington City Council develop more effective management strategies to protect threatened native wildlife.”

For more information see https://identifyanimals.co.nz.

For more information about this years awards, click here

You can reach Victor at Victor.Anton@vuw.ac.nz

Why Tuatara are so unique

17 October 2016

tuatara nickyTuatara expert Nicky Nelson of Victoria University spoke with RNZ about everything you need to know about one of the world's most unique animals.

Tuatara are in an order of their own, one of four types of reptile. They are not dinosaurs as some have suggested, but date back 230 million years.

Listen here:

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Systematically Surveying the Ants of Tetiaroa

13 October 2016

Ants are some of the best hitchhikers in the world. This is so true that in the Pacific, it’s hard to unravel whether the ants on even remote motu are native or ancient introductions with original voyagers. There are now countless examples of where introduced ants have gone on to become highly invasive, such as the ‘stinging rain’ in the Pacific. Luckily, scientists are now developing the ability to eradicate ants from islands. Given what we know about the potential impacts of introduced ants, and how little we know about the ants of Tetiaroa, our research team this week are visiting theTetiaroa Society Ecostation at the Hotel Brando on Tetiaroa to systematically survey the ants of Tetiaroa.


By systematically sampling we will be visiting every motu of the atoll to construct its individual ant species list using standardised comparable methods. Today our team of ant experts, Dr Monica Gruber from Pacific Biosecurity in New Zealand and Dr Herve Jourdan from the Institute of Research and Development in New Caledonia have visited the five most isolated south-eastern motu of Tetiaroa. On each motu we set-up pitfall traps across the motu to maximise spatial coverage as much as possible, and also undertook visual surveys to identify ants. Where time allowed bait cards were also used to attract ants in to the open.


From these motu today about 20 ant species have already been identified, although final confirmation will have to wait until they are properly identified under microscope back in the laboratory. From this census of the ants of Tetiaroa we hope to provide recommendations to the Hotel Brando on managing introduced ants on the atoll. This could include biosecurity to prevent new ant species, such as the stinging rain, arriving at Tetiaroa, or recommendations to prevent the further spread of existing ants to other motu in the atoll. If we are really lucky, we may even find a rare potentially native ant species in this far-flung corner of the Pacific.

Sourced from National Geographic

New Zealand’s biosecurity threat from corrupt and poorly governed countries

15 June 2016

fire ants

New Zealand could dramatically reduce outbreaks of invasive species if it selectively chose its international trade partners, research from Victoria University of Wellington suggests.

New Zealand receives imports, including those with unwelcome invasive species, from all around the world—but these invaders come at different rates from different countries, and are a leading cause of extinctions and the current biodiversity crisis.

The study, published today in the Royal Society journal Proceedings B, reveals that a country’s levels of governance and development strongly influence their risk of exporting exotic species.

“We found counties with poor regulation and low political stability pose more of an invasive species risk,” says Evan Brenton-Rule, a PhD student from Victoria’s School of Biological Sciences.

“If New Zealand carefully selects trade partners based on these factors, we could expect up to nine times less invasive species coming to the border.”

Co-author Professor Phil Lester says biological invasions cost New Zealand hundreds of millions of dollars a year.

“When you consider the amount that is spent on biological invasions in New Zealand, anything we can do to target our biosecurity resources and limit the number of invaders at our border would be extremely beneficial. For example, the eradication of just three small nests of the red imported fire ant into New Zealand cost in excess of ten million dollars.”

The study analysed international trade volumes from Statistics New Zealand, and ten years of data on trade interceptions at the border from the Ministry of Primary Industries. Over this time there were nearly 50,000 interceptions.

“Although an extreme option, it’s interesting to look at how selectively trading with certain countries could dramatically influence the number of biological invasions in New Zealand,” says Mr Brenton-Rule.

“It’s worthwhile thinking about how international trade deals and a change in trading partners may impact the number of exotic species knocking on our country’s door. There are millions of dollars of control or eradication programmes at stake here, as well as potential biodiversity loss”.

Making a mockery out of our native plants

15 June 2016

A Victoria University of Wellington study has revealed remarkable similarities between two New Zealand plants, and shown possible use of an age-old defence mechanism previously seen only in animals.


The study compared the size, shape and pigmentation of hundreds of leaves on horopito and small toropapa plants, and found a perfect match.

“Small toropapa is often mistaken as horopito—also known as the New Zealand pepper tree,” says Karl Yager, a PhD student in Victoria’s School of Biological Sciences.

“Over a third of the leaves of the two species cannot be statistically distinguished from one another. Unless the plants are flowering or fruiting, the only fast way to tell them apart is to taste a leaf.”

Mr Yager says this exact match between horopito and small toropapa provides tantalising evidence of what is called Batesian mimicry.

“Batesian mimicry is a common evolutionary tool where unprotected species imitate harmful or poisonous species to protect themselves from predators. Because of horopito’s pungent, hot peppery taste, that leaves one with a numb tongue when a leaf is chewed, it is unpalatable to predators,” he says.

“On the other hand, the small toropapa is highly palatable and largely defenceless. It is possible that the small toropapa has evolved its leaves to resemble the horopito and confuse would-be predators.

“To date nearly all the research on mimicry comes from animals and although this research does not prove Batesian mimicry in plants, it provides the first detailed evidence consistent with Batesian mimicry.”

As small toropara were possibly eaten by moa it is likely that it evolved in response to moa domination, Mr Yager says. “Unfortunately we can't directly test this but it provides an exciting hypothesis for future studies on Batesian mimicry in plants.”

The study, published online today in Botany, was co-authored by Karl Yager and Professor Kevin Gould from Victoria University, and Dr Martin Schaefer from the University of Freiburg in Germany.

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Studying the behaviour of potential rhino horn poachers

23 May 2016

From the African savannahs to Kelburn is a leap of both distance and imagination, but a group of Victoria University of Wellington biology students is carrying out an experiment to learn about the behaviour of potential poachers of rhinoceros horns.

The BIOL 328 Behaviour and Conservation Ecology students are working to understand how poachers may change their behaviour if rhino horns are poisoned.

“There’s an idea to try to reduce the number of rhinos being killed for their horn,” says student Sean Rudman.

“This is to poison the rhino horn so that it becomes worthless on the international traditional medicines market. This will hopefully reduce the demand for rhino horn. But then a problem occurs—if you’re poisoning horn, the remaining unpoisoned horns become more valuable. We’re looking at how human behaviour and decision making around killing a rhino for its horn may change if it’s poisoned horn.”

To study this, the students have conducted a role-playing experiment, where they’ve hidden a number of stakes (representing rhino horn) around Victoria’s Kelburn campus.

“We’ve randomly selected twenty people from our class to be poachers, and go and find those stakes. This hunt takes place four times—the first time all twenty of the stakes are worth $5 each if found, and the second time half of them are worth nothing, but the other half is worth $10,” says Sean.

“The third time only two stakes are valuable, but worth $50 each to the poacher. And the fourth time all the stakes go back to being worth $5, to control for class engagement changes over the length of the experiment. Additionally, if a poacher finds a poisoned horn, they can choose to ‘kill’ it or not.

Three guards are also hired to protect the stakes from being found, or to catch the poachers in the act. They receive the money of any stakes that remain at the end of each experiment.

“Essentially we’re looking at how people behave in response to these different scenarios, and how the behaviour of our poachers changes when the monetary reward is larger but more effort and risk is required,” Sean says.

“We’re getting feedback on how many rhino horns were found, how many were killed, and the effort our poachers went to to find the stakes. We’re also interested in if the participants made any agreements, for example, between the poachers and the guards—because that’s quite informative for understanding people’s motivation and behaviour.”

Sean has been working on the experiment with fellow students Adam Sive, Caitlin Jackson and Pip Fauvel.

Rhino conservation has personal importance to Sean. “My family is from South Africa, and my uncle lives on a game reserve with white rhino. It’s quite close to home.”

BIOL 328 lecturer Associate Professor Wayne Linklater says the experiment has proved a great learning exercise. “The students have enthusiastically involved themselves in the different scenarios. It’s been great to see them learning about the interaction between humans, economics and wildlife conservation.”

The students will individually produce a report about their findings, as well as a scientific poster.

A video of the students can be found at: https://youtu.be/wYySUA_681g

Kaka conflict: conservation icon to pest

10 May 2016


The sound and sights of kaka – cries across the valley, dog-fighting in the sky, and cart-wheeling in my kowhai tree – simply awesome.

But amongst growing numbers of people with damaged trees, fruit and, increasingly, their buildings, kaka are changing from a delight to a problem.

Kaka had been extinct in Wellington for over 100 years. They were restored in 2002 when six captive-raised kaka were released into the Karori Wildlife Sanctuary.

Their successful reintroduction and further captive releases may also have attracted kaka to Wellington from Kapiti and the Wairarapa. Provided with artificial food and nest boxes, the population has grown to over 200 birds today.

And the kaka population continues to grow rapidly. Outside Zealandia, the city has proved to be rich with natural foods and cavities for nesting, and their predators are controlled. Residents have begun feeding kaka too. Twenty-two per cent of residents visited by kaka report feeding them.

The potential, therefore, is for hundreds more kaka in Wellington, if not thousands, because the world's parrots like living in cities. They can reach higher densities in cities than they do in their native forest habitat.

Kaka damage to the Botanic Garden's collection of rare, and historically and culturally important trees was noticed first in 2009. Kaka were seen tearing bark from trees and gouging the wood deeply to feed on sap and insects.

Most of the Botanic Garden's pine, cypress and cedars will not survive the kaka onslaught. Then someone noticed the deep gouging of eucalypts and limb death in city parks and the costs of park-tree management increased.

In a 2012 survey of Wellington residents, a quarter reported problems with birds on their properties and a quarter of those problems were attributed to kaka. Fourteen per cent of respondents described the problems as moderate to severe and costly because they required the removal of damaged trees. In 2013, in the suburbs around Zealandia, 26 per cent of residents reported property damage from kaka.

Kaka are now also damaging the roofs of older city residences. We know this because, like kea in the south who have a taste for lead flashings and headed nails, some kaka are dying of lead poisoning.

Remarkably however, the contemporary attitudes of Wellington residents to kaka were positive. Over 80 per cent of people thought native birds should be in the city and that inconveniences or minor damage should be tolerated – we are a city of people highly supportive of native wildlife.

But we are much less united when it comes to managing native species that cause more serious damage. Half of us thought a native species damaging property should be controlled. The release of kaka into Wellington has initiated a new, costly and protracted human-wildlife conflict.

Perhaps reintroducing kaka to a city wasn't such a good idea – a tremendous mistake by conservationists?

As the rate and severity of damage by kaka grows, I expect support for kaka, and perhaps conservation generally amongst some, to suffer. Indeed, in a recent study residents who suffered kaka damage were less positive about kaka being in Wellington City.

Worse still, will some of those seek compensation, or for kaka to be removed or a flock destroyed?

Kaka can't be owned. Under Section 57 of the Wildlife Act, they are the property of the Crown and the Crown is not liable for the damage they may cause. But history tells a different story. If 'pushed' the Crown does sometimes, eventually accept some liabilities or at least responsibilities for solving the problem, as they have when Kaikoura seals sleep on State Highway 1 or kea mutilate high-country sheep.

Consider too that if kaka had recolonised Wellington City without assistance they would have been in small, unsupported numbers. Instead kaka are here in large and growing numbers because they were reintroduced and artificially fed and bred to be abundant by conservation organisations.

Might those organisations also, then, be responsible for kaka damage?

Like organisations that mine or harvest our natural resources, conservation organisations are also responsible for their environmental and social impact. I fear the potential of a political and legal backlash against conservation if property damage by kaka grows. This aspect of New Zealand environmental law has not been tested but it might be.

What can be done? Zealandia and local residents could stop feeding kaka and providing nesting boxes. We shouldn't be encouraging the extreme numbers that artificial food and nests supports.

And, if numbers and damage continues to grow, Kaka will need to be managed. Troublesome birds might be captured and rehomed far away. We should prepare ourselves for a time too when flocks may need to be destroyed, although perhaps usefully as a routine cultural harvest. But rehoming and culling are only temporary fixes because some kaka will find their way back and others will take their place.

Eventually and at cost, residents will need to modify their gardens and buildings so that they are less vulnerable to kaka damage.

Most importantly, conservationists must learn from the Wellington-kaka experience.

Wellington is now a city, not a forest. Just because kaka lived here once, it does not follow logically that they should live here again. Conservationists should consider people before native species are restored.

I love kaka. But their introduction to Wellington City is proving to have been a mistake.

Wayne Linklater is Associate Professor of Conservation Science and Director of the Centre for Biodiversity and Restoration Ecology at Victoria University.

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How munching Moa affected plant evolution

18 January 2016

The snacking habits of the now-extinct Moa may have influenced the way certain plant species evolved, according to new research from Victoria University of Wellington.

For his PhD in Ecology and Biodiversity, Patrick Kavanagh compared plant species on offshore islands to their close relatives on the mainland to assess differences in size and growth patterns.

“I found that island species tended to produce larger seeds, which may be advantageous on an island because if the seeds are too easily dispersed they could end up in the ocean,” says Patrick.

The rest of his thesis was focused on the role that herbivores play, which led him to the Chatham Islands to conduct fieldwork.

“In New Zealand we have plants that develop a unique growth form— characterised by high-angled branching, leading to a tangled mass of branches, and very small leaves. But in the Chathams that sort of growth form is nowhere near as prevalent—many related species don’t show it at all, with branches that are more upright and which don’t cross over so much. The leaves are bigger too.”

Patrick says there have been a variety of hypotheses over the years to explain this. “It’s been suggested that the high-angled tangle of branches we see on mainland New Zealand provides protection from wind and frost, but it’s a lot windier on the Chatham Islands.”

However one known difference is that Moa never reached the Chatham Islands. “It seems quite logical—a reduction in herbivory pressure on the plants would have relaxed the need for small leaves that are hard to reach, meaning that the island species were able to grow bigger leaves to intercept more light and be more productive.”

For the last part of his thesis Patrick narrowed his focus to one species: the lancewood, also known as horoeka or Pseudopanax crassifolius.

“The lancewood is pretty amazing and unique. It starts out with rigid, saw-like leaves when it’s juvenile but at about three metres in height, the leaves become wider and more rounded in shape. It’s no coincidence that three metres is the same as the maximum height that the largest Moa species was able to reach.”

While this theory has been around for some time, Patrick has added weight to the argument with his examination of the changes in colour to the lancewood leaves as the plant matures.

“There are small green spots on the top side of the leaves which are associated with the lateral spikes down the sides. These spots are most conspicuous when the plant is poorly developed and therefore most vulnerable to predators—the spots act as a kind of untruthful signal to deter moa and other herbivores from eating it.

“I also noticed that the underside of the lancewood leaf changes colour as the plant develops. Small seedlings are light green underneath the leaf, but that turns dark red when it reaches sapling stage. It changes back to green when the plant is fully grown.”

Patrick used spectral analysis techniques to test whether the dark red colouration makes the leaves more conspicuous to herbivores looking up from below. “The higher contrast of dark red against the other green foliage happens when the leaves are most spikey and therefore best defended. In this phase of the plant’s life, it’s a more truthful warning to any bird planning to eat it—there’d be painful consequences.”

Patrick has been working at the Ministry for the Environment, and in 2016 will carry out post-doctoral research at Colorado State University in Fort Collins in the United States.

For more information contact Amy Holmes on 04-463 5269 or amy.holmes@vuw.ac.nz