New Zealand remains under "intense pressure" from pests, which are costing our economy billions of dollars each year.

A new report launched by the Royal Society of New Zealand this afternoon says much more needs to be done to protect our precious biodiversity, with weeds, wasps, rats and sea squirts among a swarm of pests and diseases costing our economy and environment dearly.

It found "urgent action" was needed to develop better ways of waging the war on pests.

"The inherent limitations of existing pest management approaches underline the need for either new technologies or on-going refinement of existing methods," the report said.


"In particular there needs to be a trend away from the use of pesticides to more knowledge-intensive, biologically based control systems."

There was a need for "intensification and integration" of existing research efforts - and doing nothing was not an option.

The report comes as pest control efforts have been ramped up to protect 25 million native birds a year over the next five years, in what Conservation Minister Nick Smith has dubbed the "the battle for our birds".

The new report points to research that weeds are conservatively estimated to cost the economy $1.2 billion per annum in lost animal production and control costs and could potentially degrade seven per cent of the conservation estate within a decade, corresponding to a loss of native biodiversity equivalent to $1.3 billion.

"Mammal pests including rats, possums and feral cats are a serious threat to native flora and fauna, and the cost-effective, humane management of vertebrate pests at very large scales is a pressing issue," said Dr Stephen Goldson, Fellow of the Society and co-author of the report.

"There are also very substantial environmental costs associated with loss of native biodiversity and New Zealand's clean green reputation."

The report, Challenges for pest management in New Zealand, is authored by a panel led by Royal Society of New Zealand Fellows and draws on national and international research to explore and discuss the current state of pest management and the unique nature of the New Zealand situation.

The Society is calling for ongoing targeted efforts to enable new approaches and technologies, and greater citizen involvement in order to protect our native land, aquatic environments and primary production from the increasing threat of pests.

"Our economy and reputation are strongly and uniquely linked to our natural environment and New Zealand needs to maintain its position for high quality, residue-free and ethical primary production on both land and aquatic ecosystems," Dr Goldson said.

The report highlights the need for improved tools and technologies, such as fertility suppression and biological control, to counter increasing pest resistance and the loss of older, now less acceptable pest management tools.

The report also emphasises the need for more species-focused biological research, including population processes of individual pest species, so that new approaches can be developed and appropriately targeted.

"Research into monitoring and surveillance technologies is also critical, because early detection of pests is essential to successful eradication, which is by far the best option," Dr Goldson said.

"There are new technologies that are increasingly being used to help with this effort, including the use of various attractants to uncover the presence and dispersal rates of invaders."

With this, there was also a real opportunity for more citizen involvement, he said.

"New Zealanders are very motivated when it comes to their natural environment and could probably play a much greater monitoring and surveillance role.

"Obviously they need to be armed with information, and be involved early on."

In January, Dr Smith announced the Department of Conservation would be throwing $21 million toward its largest ever conservation programme.

The problem was particularly urgent this year, because the country was facing a one in 10-15 year large beech mast, which is expected to drop around a million tonnes of seed this autumn.

This would trigger a plague of an additional 30 million rats and tens of thousands of stoats, which would annihilate populations of endangered birds when the seeds germinate in spring.

The programme will increase pest control in 35 forests to protect 12 native species, and mainly involves using 1080 poison.


Pastoral weeds are conservatively estimated to cost the New Zealand economy $1.2 billion per annum in lost animal production and control costs and there are more than 300 weeds of conservation concern.

Weeds pose a threat to one-third of all New Zealand nationally threatened plant species, and could potentially degrade 7 per cent of the conservation estate within a decade, corresponding to a loss of native biodiversity equivalent to $1.3 billion.

Invertebrate plant pests

Annual production losses have been estimated to be around $880 million per annual but this does not include the impact of indigenous species that have become pests, nor the multiplier effects of their impact on economic activity connected with this production.
The costs and averted economic impacts from eradications of forest insect pests in New Zealand over 20 years, have been "significant", the report said.

The total direct economic cost of vertebrate pests to the primary sector is estimated at about $1 billion per year, but with multipliers included could be as high as $3.3 billion - or 1.96 per cent of GDP.

Annual production losses to aquaculture from a single species of sea squirt were estimated at $15 million per annum in 2005.

More recent estimates suggest that if the pest spreads to Marlborough, production losses over the next eight years could amount to $383 million.

The long term costs of loss of native biodiversity from vertebrate, invertebrate, freshwater and marine and micro-organism pests have not been estimated.

Introduced social wasps in beech forests present a case with extreme consequences for native insect and bird diversity and ecosystem services, as well as impacts on tourism and recreation.

New methods of control are clearly needed in such cases, and warrant long term government investment.

Vertebrate pests

There are only two native land mammals in New Zealand - two bat species - the result of 80 million years of geographical isolation.

In contrast, 32 species of mammals and 35 birds have become established.

New Zealand's native flora and fauna are particularly vulnerable to predation by mammal pests. Rats, mice, weasels and stoats, hares and rabbits, hedgehogs, possums, wild pigs and feral cats all present serious threats.

Strenuous efforts are being made to create vertebrate pest-free areas on islands and in predator-fenced sanctuaries.

The take-home messages

• Urgent action is needed to develop new approaches and to improve existing tools to protect the country's environment and economy.

• Ongoing targeted investment is needed to protect our native land and aquatic environments and primary production from weeds, vertebrate and invertebrate pests and pathogens.

• Changes in the use of pest management tools have been made in response to public concerns and trade issues around the environment, humaneness standards and food safety.

• Increasing pest resistance is also making some invertebrate pesticides and herbicides ineffective, while others have been phased out.

• New Zealand has already provided leadership in environmentally and socially sensitive pest management but there is an urgent need to do more.

• More emphasis needs to be given to surveillance and pest monitoring to increase the chances of successful eradication of new incursions when pest distributions are still limited, and prevent the recovery of existing pests after control has been applied.

• More trained local and central government staff are needed to assist with translating and applying scientific research and new technology, while citizen science should play a much stronger role in monitoring and surveillance for pests in New Zealand.

• More species-focused research is needed because many pests are managed with little scientific understanding of their life-cycle or population processes, and New Zealand's unique environment means we cannot presume that the behaviour of species in their native range will be replicated here.