Call them what you like – Drosophila suzukii, Spotted-Wing Vinegar flies or Asian fruit flies. They’ve come to Tennessee with a taste for sugar, an insatiable hunger and special serrated blades perfectly crafted for a full-scale attack on the state’s fruit crop. They are also a bit sneaky. Unlike domestic fruit flies that prefer ripe fruit, the Asian variety will eat unripened fruit, as well. This means farmers have to be on the look-out all season long.
Drosophila suzukii enjoy small, sweet, fleshy fruits – cherries, plums, raspberries, strawberries, grapes and blueberries. The female comes packing a serrated blade on her abdomen, which she uses to slice the fruit open and deposit eggs inside. The young ones hatch and start dining in less than a day. It doesn’t take long for the Asian fruit fly to lay waste to a fruit patch. And one bad patch is bad news for all patches in the immediate area.
Once the Asian Fruit fly has moved in, the crop is ruined. Eating contaminated fruit might make you sick. Watching insect larvae crawling out of your food might make you sicker.
The Asian fruit fly hails from Japan, where it reportedly leads an unremarkable existence, dining on, but not demolishing, the more limited local crops. Sometime in 2009, it hitched a ride to California and moved quickly eastward. The bug hit Tennessee in 2011, taking out Unicol County’s blueberry crop. Last year, crops in Warren County felt the fruit fly’s blade. Now the moveable feast has expanded to more than 10 counties in Eastern Tennessee. The state’s situation is beyond serious.
And it could get a lot worse. Nationally, the Asian Fruit fly causes tens of millions of dollars in damage every year. Much of the berry crop in the eastern US – specifically raspberries and blackberries – is currently at risk. Scientists warn that annual crop damage could soon hit hundreds of millions of dollars if the pest isn’t brought to heel.
Right now there’s only one way to deal with Drosophila suzukii: bomb them with pesticides, over and over and over again, pretty much every week during the growing season. But even that doesn’t always work, especially when the elements conspire against farmers. This year Tennessee is getting a lot of rain – according to the National Weather Service, almost two feet more than normal. No sooner is the pesticide applied, then it washes away. Fruit-fly mothers keep on slashing and their larvae keep on munching. Looking for cooler temperatures to chill out the pests? No luck there, either. The Asian fruit fly thrives in 50-degree temperatures.
Help could be coming. As scientists learn more about the Asian fruit fly, they are formulating more effective organically based defenses. For example, researchers at the University of North Carolina have discovered that the bugs demonstrate affection for specific strains of berries. They hope that planting different varieties – and tracking host plants in the wild – could go a long way toward protecting crops from the unwanted visitors.
But that’s all in the future. This year promises to be another tough one for fruit and berry farmers across Tennessee, where as much as forty percent of crops are under attack from bugs wielding serrated blades. A very sad bowl of cherries.
Written by Mike Clancy
Times Free Press