A "game changer" wasp biocontrol programme has been delayed after the two insects imported to deal with them have failed to breed in captivity and all perished.
The insects were originally planned to be released across the top of the South Island in April this year.
"This was going to be the one thing that would be so awesome for our community," says Tasman District Council’s environmental information manager, Rob Smith.
Manaaki Whenua – Landcare Research has been overseeing the application and preparation of the two insects: a species of hoverfly and the wasp nest beetle.
Project lead Dr Bob Brown said the two insects are "extremely difficult" to rear in captivity.
They were imported from England and are reared in a quarantine facility to meet criteria set out by the Ministry for Primary Industries before they’re released.
"The colonies of these two species did not survive the simulated overwintering programme that they must go through to synchronise them with the Southern Hemisphere season," Brown explained.
The artificial winter initiates diapause within the insects, an essential step to trigger their development into adults.
It’s this process in which the insects are at their most vulnerable.
"While I was extremely disappointed in how our attempt at rearing the agents this year turned out, this is a great example of the quarantine working exactly as it should, by preventing the release of any individuals that are not in the very best condition," Brown said.
Despite the setback, the programme will continue with the aim of releasing the insects next summer, though there are many steps that must go perfectly before they can be released.
"Nationally, it will be one of the biggest game changers in biodiversity. We absolutely want to see that happen," Smith said. "Hopefully, next year we’ll have a better story."
The two insects, the hoverfly species, Volucella inanis, and the wasp nest beetle, Metoecus paradoxus, both infiltrate the nests of common and German wasps to parasitise the grubs, decimating the wasp populations.
The two species go through extensive testing to make sure they’re host-specific to the two wasp species and not any of New Zealand’s native flora and fauna.
By Max Frethey for Local Democracy Reporting
Public Interest Journalism funded through NZ On Air
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