WELLINGTON, Nov. 7 (Xinhua) -- Invasive wasps have become so numerous in some of New Zealand's native forests that are posing a major health and safety risk, experts warned Thursday.
A joint statement from two government agencies and Victoria University said the densities of the common and German wasps needed to be reduced by up to 90 percent from their current summer levels to stop "havoc" being wreaked on the country's biodiversity.
Experts from the university, the Department of Conservation ( DOC) and the government's Landcare Research institute had helped to set up a Wasp Tactical Group to combat the stinging insects.
"German and common wasps can reach densities of over 350 wasps per square meter," Dr Darren Ward, of Landcare Research, said in the statement.
"Wasps are so abundant in many native forests that they pose a major health and safety risk to those working and playing outdoors. They are voracious predators that cause declines in native biodiversity and reduce our ability to enjoy recreation activities. "
Professor Phil Lester, of Victoria University's School of Biological Sciences, said scientists had been hamstrung by a lack of wasp control technologies appropriate to New Zealand conditions.
Poisoned bait stations could be effective, there was no investment in getting such systems on to the market, Lester said in the statement.
Eric Edwards, of the Department of Conservation, said biological control, such as using pathogens and parasites, would be a sustainable method to treat the 1 million hectares of forests affected.
The German wasp arrived in New Zealand with aircraft parts in 1945 and spread rapidly, while the common wasp is thought to have arrived in the late 1970s and quickly replaced the German wasp in some environments to become the most abundant species, particularly in the South Island.
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