The National Radiation Laboratory in Christchurch is irradiating batches of male painted apple moth larvae to make them sterile.
The work, contracted through HortResearch, is part of a battle to eradicate the moth in Auckland.
Aerial spraying over the homes of 200,000 people in infested areas of Waitakere, Auckland and North Shore
began in October, raising concerns among some residents about health effects of the spray.
Authorities fear the pest could ravage the forestry industry and indigenous forests.
Painted apple moths mate only once, so the sterile insect technique could, in theory, help wipe out the species in New Zealand.
The release of sterilised males to mate with fertile females has worked with other insects such as screw-worm in North America, the tsetse fly in Zanzibar, the Queensland fruitfly in Western Australia and the Mediterranean fruitfly in Mexico.
National Radiation Laboratory scientific adviser Rob Coppell said the moth larvae were irradiated with cobalt 60 using an adapted hospital machine formerly used to treat human patients.
Each batch of 50 insects received five hours and 45 minutes of treatment using 100 grays of radiation.
That was 20 times the amount needed to kill a human, but insects were much hardier, he said.
"They don't know anything about it."
The level of radiation was adjusted to render them sterile, but not enough to kill or impede their mating flights, which can cover more than 6km.
The treated moths will soon be released in the Auckland area as part of a programme co-ordained between Hortresearch and the Ministry of Agriculture and Forestry.
- NZPA
Herald feature: Environment
