Posts Tagged ‘New Zealand’



February 19th, 2015


Queensland_Fruit_Fly_-_Bactrocera_tryoni-300x298Queensland Fruit Fly – Bactrocera tryoni

Photo: Queensland Fruit Fly, via Wikimedia Creative Commons

Horticulture New Zealand has called for a bolstering of the country biosecurity measures after a single male Queensland fruit fly was found in a surveillance trap near Auckland.

The Ministry for Primary Industries (MPI) is investigating the find, which was made late afternoon on Feb. 16 in the suburb of Grey Lynn and formally identified the following day.

MPI chief operations officer Andrew Coleman said only the one male insect had been trapped and this did not mean New Zealand had an outbreak of fruit fly.

“The Queensland fruit fly has been detected five times before in northern New Zealand – in Whangarei and in Auckland. In all cases MPI carried out thorough surveillance and no further flies were found,” he said.

Coleman added the MPI had responded swiftly and field teams starting work yesterday setting additional fruit fly lure traps to determine if other flies are present in the area, and if other flies are there, preventing any spread of the pest out of the area.

“It is vital to find out if this insect is a solitary find or if there is a wider population in Auckland,” he said.

“This insect, if established here, could have serious consequences for New Zealand’s horticultural industry. It can damage a wide range of fruit and vegetables and could lead to restrictions on trade in some of our horticultural exports.”

The MPI said it had now placed legal controls on the movement of fruit and some vegetables outside of a defined circular area which extends 1.5km (1 mile) from where the fly was trapped in Grey Lynn.

Spread of pest in Australia ‘out of control’

Since the find, Horticulture New Zealand has called for the reinstalling of 100% x-rays of passenger bags at the country’s international airports until at least the end of summer.

The organization said in a release this detection was the fourth in three years and put New Zealand’s NZ$5 billion (US$3.8 billion) horticultural industry at risk.

“So far it is only one fly. And we fully support the Ministry for Primary Industries’ response to this threat,” HortNZ president Julian Raine said.

HortNZ requested the public back the Ministry’s efforts, especially in the exclusion zone areas, as it said the pest would also have big impacts on home gardeners.

It added it was laying the blame for this breach on Australia’s inability to control the pest, claiming the country’s biosecurity protection within its own state borders was ‘seriously breaking down.’

The group said that last week the residents of Adelaide were told of the second detection of Queensland fruit flies in their city in less than two months, while seven flies found in the last detection.

“South Australia is supposed to be a Queensland fruit fly free state. Obviously the spread of this pest is out-of-control in Australia and the interstate regulators are powerless to stop its progression south,” Raine said.

The Queensland fruit fly can only come from Australia and some Pacific islands, most likely via a passenger coming off a plane or on a consignment of imported fruit.

“Reinstating the 100% x-ray of passenger bags coming from across the Tasman would go a long way towards helping us improve our protection and lower this risk,” Raine added.

“It is not acceptable to go through this drama every summer. New Zealand horticulture deserves better protection.”

HortNZ added the cost to the horticultural industry would be two-fold, involving the destruction caused by the pest and the ongoing cost of attempting to control it as well as the cost of international markets closing to New Zealand’s products.


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Invasive Plant Science and Management—Attempts to achieve biological weed control with insects are met with stringent risk assessment in the United States. Before insects are released, their potential to attack economically important or threatened plants is closely evaluated. This assessment focuses on risk and does not adequately address host-range data, especially results from multiple-choice and open-field tests; therefore, it may result in missed opportunities for safe, effective, and natural weed control.

An article in the journal Invasive Plant Science and Management examines five successful cases of insects released in the United States for weed control. Prerelease and postrelease data collected for these insects (known as agents) are compared to evaluate the safety of biological weed control. In general, experimental host range data accurately predicted or overestimated the risks to nontarget plants.

Before releasing an insect to control weeds, the benefits and risks are weighed. An herbivore is tested, one plant species at a time, under confined conditions to determine its fundamental host range. But to establish its realized host range, under natural field conditions, an insect is allowed to choose from among the target weed and other potential host plants.

The U.S. Department of Agriculture Animal Plant Health Inspection Service is the agency responsible for biological control introductions. Recent decisions by the agency favor a conservative approach that focuses solely on the fundamental host range. While this is a safe methodology, the authors of this analysis argue that this criterion significantly overestimates the risks posed by an agent, thus limiting biological weed control options.

The authors contend that five agents, historically proven as successful, would not have been released under today’s assessment standards. These include a leaf beetle, mite, and weevil that reduced populations of

A reassessment of current policy is proposed to enable the consideration of both benefits and risks of all management options, such as biological control, but also herbicides or non-action. Focus should be at the habitat level, rather than for individual species of concern. In the long term, the authors believe that biocontrol legislation should be amended to include this risk–benefit analysis, ideally, early on in the control program, noting that this has proven effective in New Zealand and Australia.


About Invasive Plant Science and Management
Invasive Plant Science and Management is a broad-based journal that focuses on invasive plant species. It is published by the Weed Science Society of America, a non-profit professional society that promotes research, education, and extension outreach activities related to weeds; provides science-based information to the public and policy makers; and fosters awareness of weeds and their impacts on managed and natural ecosystems. For more information, visit http://www.wssa.net/.

Media Contact:
Jason Snell
Allen Press, Inc.
800/627-0326 ext. 410

Read the article: Invasive Plant Science and Management, 2014: Volume 7(4): 565-579

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grist NZ

Last updated 06:00 29/06/2014


Scientists are finding signs that a successful biocontrol agent might be losing its battle against a pest feeding on farming pastures.

A South American wasp could be a victim of its own success against the Argentine stem weevil with initial evidence pointing to its numbers declining and the host gaining the upper hand.


LOSING ITS STING?: The parasitic wasp sizing up an Argentine stem weevil may have lost some of its biocontrol powers.

Winter numbers were found in a published study to be down by up to 50 per cent compared with 15 to 20 years ago when it reached its peak after being released in the early 1990s.

Scientists are looking at reasons why it was less efficient with one theory being that the weevil had developed resistance to it after about 15 years of selection pressure in a pasture environment dominated by few grass species apart from mainly ryegrass and clover.

National team leader Professor Stephen Goldson, who works at Lincoln University and AgResearch, said research into the “biocontrol instability” was a work in progress, but serious investigation was needed as the initial understanding was that weevil activity was increasing.

“Based on current data and analysis it really seems there is a reduction in activity and that has been matched by reports of increased damage of stem weevils in ryegrasses in particular.”

He said scientists remained cautious about over-emphasising the wasp’s decline because they were looking at a big eco-system with host and parasite numbers constantly moving up and down depending on the season.

The wasp puts an egg inside the weevil’s body, instantly sterilising it, with the host acting as an incubator for its “alien” larvae. This larvae kills the weevil and forms a cocoon and another wasp. Three generations are produced over summer and the parasite and host go into hibernation in winter to crank up numbers in spring.

Scientists believe the wasp’s inability to produce males – it only creates clones of identical daughters of the mother – could be partly behind its possible downfall.

Goldson said there was a potential “perfect storm” going on between the weevil and the wasp.

“First of all the parasite can’t evolve because it’s stuck being like its mother. The weevil can evolve because it has a sexual reproduction cycle, and if enough pressure is put on a population resistance can occur. Therefore, there is no evolutionary arms race going on and usually the parasite would evolve to keep up with changes to the host, but it can’t and the other component of this storm, and it’s somewhat speculative, but the eco-system we have on our pastures is remarkably simple.”

Pastures based mainly around ryegrass and clover allow pests such as the weevil to grow to large numbers because they have no enemies. Until now parasite numbers have also been able to explode and this is why biocontrol agents have been so successful in New Zealand pastures.

Goldson said a strong line of thinking was that weevil survivors were struggling to hide in the simple pastures which usually slows down the rate of resistance.

In the mature eco-systems of many other countries, pests could escape selection pressure and crossbreed with ones that have evolved to slow down resistance, he said.

He said the investigation was being taken seriously because clover root weevil also had a biocontrol wasp.

No white clover plants have yet been found to be resistant against the clover root weevil and farmers are dependent on an Irish wasp for its control, estimated to be worth $444 million a year for farmers in reduced pasture damage.

Old data collected nationally from the 1990s helped the national team track wasp numbers waning a year ago. The data was kept but research funding went elsewhere because of its success.

Research into what is going on between the stem weevil and the parasite is being carried out by the Bio-Protection Research Centre at Lincoln University and AgResearch with support from the Foundation of Arable Research and DairyNZ.

Among theories are that there has been a genetic shift in the weevil and this is being investigated by a team of molecular biologists.

Goldson said scientists had yet to look at options which could include the unlikely chance of finding other strains of the parasite in South America or developing new pasture management such as using more plant species.

The research is attracting international scientific attention because there is only one recorded case of a host developing resistance and that was in Canada involving the larch sawfly and a wasp.

– The Press


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Friday 4th April 2014, 01:49 London

Whangarei again the site of incursion, only months after authorities deemed another discovery an isolated incident


New Zealand’s fresh produce industry is again on high biosecurity alert, after the discovery of a second Queensland fruit fly (Q-fly) in Whangarei within three months, according to media reports.

The New Zealand Herald claimed the discovery was made in a surveillance trap located just 400m from where another Q-fly was detected in January. In that instance, heavy restrictions were place on fruit and vegetable trade in the region while a large-scale response operation, involving close to 50 quarantine officials, was undertaken.

New Zealand’s Ministry for Primary Industry’s (MPI) does not believe the two cases are related, after the investigation into January’s incursion determined it was an isolated incident, with no breeding population of Q-fly. A new control area has been established, with the movement of fresh produce around Whangarei again restricted.

“As in January, it is vital we find out if the insect is a solitary find or if there is a wider population in Whangarei,” MPI spokesman Andrew Coleman told SkyNews. “This insect is an unwanted and notifiable organism that could have serious consequences for New Zealand’s horticultural industry and home gardeners. It can damage a wide range of fruit and vegetables.”

January’s two-week response operation cost New Zealand taxpayers almost NZ$1m (US$850,000). New Zealand Green Party biosecurity spokesman Steffan Browning said this week’s discovery questioned the validity of the January campaign and the country’s biosecurity systems in general.

“Given that the last fruit fly was found in the same region only a few months ago it seems likely there is a connection,” Browning told the New Zealand Herald. “If it is the case that this fruit fly is linked to the previous incursion, then it raises serious concerns about MPI ending their January campaign early, before ensuring there were no other fruit fly in the region.”

Kiwifruit Vine Health chief Barry O’Neil said the discovery posed a low risk to the region’s kiwifruit crop, with no orchards within the control area.



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