Wasp Wipeout reloaded

Summer is around the corner and it’s buzzing with potential – the potential for wasps to make a nuisance of themselves again.

Stuff’s Wasp Wipeout is back and better than ever, gearing up to take out every barbecue’s worst nightmare.

Starting out as a local effort in the Nelson Tasman region in 2016, the wipeout has spread just like the invasive wasp species it targets to occupy most of New Zealand.

This summer the target is expanding from common and German wasps in the top half of the South Island, to include harder-totarget paper wasps and covering Te Tauihu (top of the south), the West Coast, Canterbury, Central Otago, Wellington and Auckland.

Department of Conservation Wasp Wipeout project leader Adam Riding said vespula wasps were present in large numbers in Marlborough which could have a negative impact on the biodiversity in the area. ‘‘But the exact locations tend to vary year on year.’’

This year Wasp Wipeout would repeat the baiting with Forest and Bird to treat the Pelorus Bridge area for wasps, which would improve the recreational experiences for campers and the safety of the Forest and Bird volunteers who are trapping predators in the area, Riding said.

The German and common wasps were susceptible to Vespex bait which would be laid in wasp-dense National Parks and beech forests in areas like Lake Rotoiti, Abel Tasman National Park and the Marlborough Sounds.

Over the summer, Wasp Wipeout would look to expand the programme to Queen Charlotte Track.

‘‘This season we hope to repeat the wasp baiting sites conducted last season and expand into other areas where wasps turn up this year,’’ Riding said.

Stuff, the Department of Conservation, the Tasman Environmental Trust and Conservation Volunteers New Zealand have combined forces to track wasp populations and at just the right time, usually midto-late summer depending on wasp activity and numbers, hundreds of volunteers and DOC staff hit the great outdoors with bait.

The protein-based bait is carefully designed and administered to target wasps with as little risk to other animals or insects as possible. The active ingredient, fipronil, is at a concentration of 0.1 per cent, a lower concentration than the same active ingredient found in common flea-treatments for cats and dogs.

However, to be safe, the bait stations are attached to trees in a way that makes them difficult for most animals to reach. Because the poison is effective against any insect that might find it, it is removed within eight days to minimise the chance of poisoning non-target insects. Bees don’t take the bait as they don’t eat protein.

A 2017 study found that in just four days Vespex reduced wasp numbers by 94 per cent, and longer exposure had an up-to 98 per cent reduction in the wasp population.

New Zealand, and particularly the Nelson Lakes region, has some of the highest wasp densities in the world, with up to 40 nests per hectare of forest and a biomass that dwarfs rodents, birds and stoats.

Despite the up-to 98 per cent effectiveness of Vespex at clearing wasps out of even the highest population areas, the poison needs to be readministered every year as a queen wasp can fly vast distances, up to 70 kilometres, to find the perfect spot to build her nest.

Just one queen can re-infect an area to the tune of thousands of individual wasps stripping the forest of honeydew, nectar, and insects.

The cost of wasps to New Zealand’s economy has been estimated to be $130 million per year, mostly thanks to wasps systematically destroying beehives, taking the legs out from under honey-producers and having a flow-on effect on farmers.

The costs to the environment are much higher, with multiple studies showing that the overwhelming presence of wasps, which have no natural predators in New Zealand, can put native insect populations in a tailspin, and effectively take out the food sources that every native animal relies on.

Vespex wipes out entire nests in one hit thanks to the way wasps eat. Though the adult drones are the ones gathering all the honeydew and insects from the bush, they actually have very poor digestive systems and can’t digest any of it themselves. Instead, the wasps bring everything back to the nest and feed it to the larvae, which then feed the adults with a predigested meal.

When wasps take the proteinbased Vespex bait to the nest and feed it to the larvae they wipe out the next generation of wasps, which either live long enough to process the bait into a digestible form for the adults, passing the poison on to them, or die and leave the adult wasps with no way to digest food.

Unfortunately, paper wasps are trickier to target, because unlike the more opportunistic vespula (common and German wasp) species, paper wasps only eat live insects. This, as well as paper wasps’ preference for more urban areas, means tackling paper wasps has to be a communal effort, usually involving a can of spray.

Last year’s Wasp Wipeout raised over $80,000 towards clearing South Island forests of their most effective predator, covering more than 30,000 hectares of bush with the help of hundreds of volunteers and DOC rangers.

Keep an eye out on Neighbourly and Stuff for more as we help you tackle this common backyard invader, along with ways to get involved as a Vespex volunteer or donor, and be part of the story by submitting your experiences with wasps to Stuff Nation.

Wasp Wipeout is a collaboration between Stuff, the Department of Conservation, the Tasman Environmental Trust and Conservation Volunteers New Zealand. Donations can be made at https://givealittle.co.nz/cause/ wasp-wipeout-1