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On the Front Lines of an Invasion

Hannah Burrack adjusts the focus on a microscope in her entomology lab, bringing a curiously scruffy female fruit fly into view. She points out a dark jagged fin extending from the fly’s backside like a tiny Ginsu knife.

Unfortunately, the fly uses the appendage to do more than just slice up fruit.

“It’s an ovipositor,” Burrack explains.

Remember your Latin? That’s ovi, for eggs, and positor, meaning “one who places.” The fly’s ingenious anatomy enables her to cut through the skin of a raspberry, blueberry or peach, and deposit her eggs safely and covertly beneath the surface. After the larvae develop, in about five days, they destroy the fruit from the inside.

Invasion on Spotted Wings

A container of raspberries infested with fruit fly larvae.

The pest, called the spotted wing drosophila, is new to North Carolina, arriving here from Asia in the summer of 2010. Although it has infested fruit at a few commercial farms in the past two years, Burrack worries things could get out of hand in the years ahead as the invasive species spreads throughout the state and region.

“They’ll eat anything soft and sweet,” she says. “If left unchecked they could reach 100 percent infestation. Every single fruit in a field could be infested by these guys.”

While its cousin, the native fruit fly, feasts on rotting fruit, the newly arrived spotted wing fly prefers ripe fruit. That’s a problem for growers. On the West Coast, where the fly arrived in 2008, it has infested berries, cherries, nectarines and figs, resulting in losses topping $2 billion in the first year alone.

Advice for Growers

Burrack works with growers across North Carolina through the university’s Cooperative Extension program to help them understand the risk. She offers advice on how to detect the pest and what to do in the event of an infestation. But she doesn’t have an ideal method of prevention.

Hannah Burrack hopes research into the genetics of the fly will give scientists a way to manage the invasive species.

“The tool for managing this pest is relative high levels of pesticides,” she says. “That’s not sustainable, economically or environmentally.”

Burrack says the emergence of the spotted wing drosophila underscores the importance of NC State’s integrated pest management program, which works with growers to control pests with the least possible impact on the environment.

But the long-term answer to the problem, she says, will ultimately come as a result of sustained research.

“We need to learn more about the biology of the organism, and then use that against them,” she says. “But this is not the only crisis in agriculture. Everybody’s competing for a very limited pool of money.”

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