To fight berry-busting fruit flies, researchers focus on sterilizing the bugs

Paul Nelson is used to doing battle with an invasive fruit fly called the spotted wing drosophila, a pest that one year ruined more than half the berries on the Minnesota farm he and his team run. In recent years, they've cut their losses closer to 5%, but it's been labor-intensive and expensive. 

“It’s a pest that if you’re not willing to stick the time into it, it’s going to take over your farm,” said Nelson, the head grower at Untiedt's, a vegetable and fruit operation about an hour west of Minneapolis. 

Nelson and other growers may someday get a new tool as a result of research at North Carolina State University into the insects, which ruin the berries by laying their eggs in them and have been estimated to cost growers hundreds of millions of dollars annually. The researchers, using a concept called “gene drive,” manipulated the insects' DNA so that the female offspring would be sterile, and the method they used to achieve it significantly reduced the chance that a population could rebound. 

The researchers, whose work was published Monday in the Proceedings of the National Academy of Sciences, found if they bred one of their modified flies with a non-modified fly, up to 99% of the offspring would inherit the sterility trait. They used mathematical modeling to show that if they released one modified fruit fly for every four that were not and did that every two weeks, they could collapse a population in about five months.