Tau fly monitoring continues as insect poses risk to $7bn horticulture industry

Monday 25th January 2016

The hunt for the tau fly continues in Auckland, with growers nervous about the potential impact on the $7 billion horticulture industry.

The Ministry for Primary Industries began investigating after one male tau fly was found in a surveillance trap in Manurewa last Thursday. MPI monitors for the presence of about 100 species of fruit fly using lure traps, as the absence of the flies enables export of fruit and vegetables without it needing to be treated. In the 2014-2015 season, there were 4,920 traps in Auckland, of 7,651 nationwide.

There have been nine interceptions of economically important fruit flies since 1989; most recently, a small population of the Queensland fruit fly, which was found in Auckland's Grey Lynn last February. MPI declared it eradicated in December 2015, with the project costing over $13.6 million. For the year ended June 2014, horticulture exports were worth $4 billion, with total produce valued at $7 billion.

Horticulture New Zealand's chief executive Mike Chapman said the tau fly was less of an economic threat to New Zealand than the Queensland fruit fly, though it was still a nervous time for growers.

"We don't think it's going to establish," Chapman said. "It does have less host plants than other flies, but also the chance of it establishing in New Zealand is more remote as it's a tropical fruit fly. It comes from hotter climates than those we might see from Australia."

MPI has restricted the movement of pumpkin, melon, cucumber, capsicum, zucchini, beans and passionfruit plants and fruit from within the controlled area, which encompasses a 1.5 kilometre radius around the Manurewa trap where the fly was found.

Some 80 percent of New Zealand's horticulture crops are susceptible to attack by Queensland fruit fly. The tau fly risk affects fewer crops, with a preference for cucumbers, pumpkins and zucchini, though the risk for those host plants is very serious, Chapman said.

Exports can be jeopardised by the presence of fruit flies, and treatment is costly.

"It makes it more awkward to get the vegetables into the markets you're trying to get them into," Chapman said. "Everything that's an additional cost is an additional barrier, and you may get some countries saying we don't want your fruits and vegetables because of this."

Chapman was confident in the trapping and surveillance program run by MPI, and hoped to see no more tau flies found.

BusinessDesk.co.nz

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