Another invasive fruit fly found

Oriental fruit fly

Authorities found one more Oriental fruit fly in Morgan Hill since the state declared a local infestation of the potentially destructive, non-native insect, but the farming community is encouraged that a “devastating” quarantine of crops headed for markets out of town will not be initiated.

A total of four male Oriental fruit flies have been found near the intersection of Tennant Avenue and Monterey Road, according to Santa Clara County agriculture commissioner Kevin O’Day on Monday.

One fly was found each day from Monday through Thursday of last week, but since the state Department of Agriculture enacted an eradication effort to squash the insect population before they have a chance to breed, no more invasive flies have been found, said O’Day.

The state announced the area was infested with the bugs, which can burrow inside unpicked fruit and vegetables and lay eggs that destroy the crops, after the first three flies were found last week.

If two more flies are found, or if one pregnant female fly or one larva are discovered within the next two life cycles – about two months or so – the county would be required to quarantine all fruits and vegetables grown in the affected area, O’Day said.

Such a blow to local farmers would be “very significant,” but the fact that no more Oriental fruit flies have been found since Thursday is good news, said Santa Clara County Farm Bureau executive director Jennifer Scheer.

“To be completely silent for three days in a row is an encouraging sign,” Scheer said.

The Oriental fruit fly is typically only found in Hawaii, the Philippines, and areas of southern Asia, O’Day added. It is likely the flies found in Morgan Hill entered this area aboard fruits or vegetables from one of those areas – through an unauthorized shipment, undeclared produce carried across the ocean by human travelers, or “care packages” sent to Morgan Hill from another area.

Even if authorities are able to quickly eradicate the flies through a bait and pesticide trapping procedure, Scheer added that an ongoing concern is the possibility that the insects could be accidentally shipped into the county again.

The Farm Bureau could not estimate the potential monetary damage that would result from a quarantine, but O’Day said more than 200 types of fruits and vegetables – including plums, peaches, peppers, grapes and most other crops grown in south Santa Clara County – can host the Oriental fruit fly.

The female bugs can wipe out crops by burrowing under the skin of the host fruit and laying eggs, which hatch into maggots. “That’s where the damage occurs. They tunnel through the fruit and feed under the surface, and secondary rot organisms could occur,” O’Day explained.

In 2010, the total value of vegetables grown in Santa Clara County was about $140 million, and the value of fruits was more than $12 million, according to the county crop report for that year.

“A lot is at stake here,” O’Day said.

Scheer added the Oriental fruit fly infestation has “terrible timing” because the growers of many of these crops are preparing to harvest before the end of the summer. If more flies are found and a quarantine is declared, they would be required to spray their fields and orchards. Some growers have already decided to begin spraying for the flies as a preventive measure, out of their own pockets.

A quarantine would only prohibit the shipment of fresh produce, so growers could process their crops or sell them to a processor in the event of a quarantine, Scheer explained. But that might not be worth it because processors pay a lower price than buyers on the fresh market.

“The crop might be totally lost,” Scheer said.

Andy Mariani, owner of Andy’s Orchard in northeast Morgan Hill, said a quarantine would cost him “between $10,000 and $50,000,” and most likely in the $40,000 range which he called “devastating.”

Sales of fresh peaches, nectarines and plums – which he is harvesting now – at his fruit stand would be prohibited. Shipment of these crops to his usual wholesale buyers throughout the Bay Area and across the country would also be prevented.

“I would have to close the store for a while. The only thing I could do is dry (the fruit),” Mariani said. He couldn’t even donate the produce to local food banks because they serve clients outside Morgan Hill.

One area of the industry that would be mostly unaffected by a quarantine is the county’s $7 million wine industry, Scheer said. Grapes grown for wine have to be processed anyway, so any Oriental fruit flies attached to those crops would not survive beyond shipment, and especially not if the fruit is processed locally.

In response to the infestation, state agriculture authorities set up bait stations with a thick gelatinous substance containing female insect pheromones and pesticides that attracts the male fruit fly. That substance has been placed high in the air on trees along streets in the area and telephone poles within a 16-mile radius surrounding Tennant Avenue and Monterey Road, O’Day said.

By wiping out the male flies in this method, any females in the area have no one with whom to reproduce, and the Oriental fruit fly “collapses,” O’Day said.

The same treatment has been used in Santa Clara County before – most recently in 2010 when Oriental fruit flies were found in Milpitas – and have been effective, O’Day added. A similar eradication effort is under way now in Orange County.

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