Biosecurity staff have checked grocery stores inside the restricted area in Auckland in which a male Tau fruit fly was discovered, owners say.
A 1.5km exclusion zone has been established around the site where the fly was found last Thursday, close to Manurewa High School.
Some types of fruits and vegetables - including pumpkins, cucumbers, beans, and melons - cannot be removed from the zone although they can still be taken in.
Subhas Chand sells onions and potatoes alongside other groceries at his Manurewa corner store.
He did not sell any produce that could carry the tau fly but had still been visited by Ministry for Primary Industry (MPI) officials.
Officials visited twice, and had noted there were no vegetables for sale in the shop, he said.
The weekly Manurewa Market is located on the boundary of the suburb's exclusion zone.
Organisers said, despite the restrictions, the market had been able to run smoothly - with 10 inspectors there last Sunday to ensure the rules were being followed.
They said one stallholder set to sell watermelons was unable to take part but all of the other venders had different fruit and vegetables to sell.
One grocery store owner, Gagan Singh, said he would also stop selling some items.
"I used to sell all these things - the pumpkins, papayas, the cucumbers, watermelons - but after that, three days ago, that staff came from food and safety, they told me [about the Tau fly] so I'm going to stop selling [them]."
Mr Singh said, while selling produce such as cucumbers and melons was generally popular, it would not hurt business if they were not on his shelves.
"It's all right. It's not a big deal if I don't sell it for three or four months. It's not a big deal for me."
Horticulture New Zealand said, due to the climate, there was only a remote chance the fly would be able to establish itself in the suburb but it would be concerned if any more were found.
It said if the Tau fly species did establish itself here, it could be a billion-dollar threat.
As well as the exclusion zone, over 95 traps have been set in the area in an attempt to stop any potential spread.
In the meantime, for local shop owners like Tushar Patel, it was about keeping an eye out.
"We've just been told to just ring up a number - we've been given a magnetic card, to stick it by the counter, and we just ring them up if we do spot one."
Mr Patel said, while he did not sell any fresh fruit and vegetables, he would be careful to obey the restrictions.
"We need it because we are a more agricultural area - New Zealand, pretty much, our economy is based on agriculture so we have to be careful of these things."
The Ministry for Primary Industries said, if no further flies were found in the next few weeks, the restrictions would be lifted.