Failure of insect breeding delays wasp biocontrol programme

MAX FRETHEY Local Democracy Reporter

A “game changer” wasp biocontrol programme has been delayed after the two insects imported to deal with them failed to breed in captivity and have all perished.

The insects were originally planned to be released 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 says 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.