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Published: 2003-09-10 00:00:00

The Waikato is at risk from invasion by the guava moth, an Australian pest which feeds on ripening fruit.

Environment Waikato’s Biosecurity Committee heard this week that HortResearch had studied the spread of guava moth in the northern North Island, and while none were trapped in Auckland, Waikato and Bay of Plenty, the Waikato was at risk from infested fruit from Northland.

The moth was first recorded in Kaitaia in May 1997, and attacked citrus, plum, peach, loquat, macadamia nut, nashi, guava and feijoa. Larvae burrow into ripening fruit, causing the infested fruit to drop, with the larvae pupating in the dropped fruit.

In November 2001 MAF said the moth was likely to be of minor importance and eradication was unlikely. However, one Northland macadamia orchard had since had 80 percent of its production destroyed by the moth larvae. Control would pose particular problems for organic growers of fruit and nuts, as the only way to control it was with chemical sprays every two to three weeks.

The survey found the moth was most likely to establish in the warmer coastal regions of the North Island and possibly the warmer northern areas of the South Island.

The moth was likely to move slowly south, and discussions were continuing with Northland Regional Council on measures to lessen the risk.