In a monumental move for conservation, the Tasman District Council has been given the green light to introduce two European insects, the hoverfly and wasp-nest beetle, to tackle the country’s chronic wasp problem.
Tasman, with its honeydew covered beech trees, has the highest density of wasp nests in the entire world, with around 30 nests per hectare with each nest containing thousands of wasps. The invasive German and common wasps thrive on the honeydew, restricting the food source for native insects and birds, while disrupting the ecosystem and costing the economy $133 million a year in damages and management.
The TDC applied for permission to introduce the insect bio control agents last September and have now been granted permission to use them. The Environmental Protection Authority has assessed the impact of bringing in these non-native species and ruled it safe.
“The reason why it’s safe is because these two insects only attack wasps and that’s been established both where they come from in Europe and elsewhere,” said Chris Hill, general manager of hazardous substances and new organisms.
Both the hoverfly and beetle will attack wasp nests. The hoverfly will lay eggs in the nest which, in turn, eats the wasp larvae.
The new insects will need to be bred here in New Zealand, and it’s thought it will take around two years before they are ready to be released into nature.
“We have to collect larvae in the wild from the UK,” says said Paul Sheldon, the Tasman District Council’s biosecurity and biodiversity co-ordinator. “Then get it back here into a suitable rearing facility. As they are coming from the Southern to Northern hemisphere, they need to retune and breed in cycles which will reset their clocks so that when they hatch, they are being useful at the right times, in the correct seasons. That will take a while.
“The attempt at bio control isn’t new,” continues Paul. “You can never be certain how much impact the new insects will have. They won’t eliminate the problem, but they will weaken the wasp population, so it will be interesting to see how well they establish and what effect that has across the country.”