Researchers are Pioneering Sterilization Techniques to Combat Berry-Destroying Fruit Flies

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Paul Nelson, a seasoned veteran in combating the destructive spotted wing drosophila, understands well the damage this invasive fruit fly can inflict. On his Minnesota farm, the pest has previously devastated over half of the berry crops in a single year. Nowadays, thanks to rigorous and costly efforts, crop losses have been reduced to about 5%.

According to Nelson, the head grower at Untiedt’s, a fruit and vegetable enterprise roughly an hour west of Minneapolis, “This pest is relentless. If you’re not prepared to invest the time, it will overrun your farm.”

A new solution may be on the horizon for Nelson and fellow growers, courtesy of research undertaken at North Carolina State University. The researchers have turned their attention to these pests, which lay eggs in berries causing extensive damage and costing growers hundreds of millions of dollars each year. By employing a “gene drive” technique, the researchers have manipulated the insects’ DNA to render female offspring sterile, significantly reducing the risk of population resurgence.

This research, recently published in the Proceedings of the National Academy of Sciences, demonstrated that when one of their modified flies bred with an unmodified one, up to 99% of the offspring inherited the sterility trait. Through mathematical modeling, the researchers showed that releasing one modified fruit fly for every four unmodified ones every two weeks could result in a population collapse within five months.

Although genetically modifying insects for pest control isn’t new, it hasn’t gained traction in agriculture due to the affordability and convenience of pesticides. Max Scott, a professor of entomology and a co-author of the paper, explains that traditional methods of releasing genetically modified insects can be costly on a large scale due to repeated releases required to eliminate pests. However, their team’s gene drive technique accelerates sterility spread through generations, reducing the number of necessary releases.

Scott expressed optimism about their breakthrough, “The system is working remarkably well.”

If proven effective in the field, this genetic approach could bolster farmers’ defense mechanisms against a relentless pest capable of obliterating 20-30% of a raspberry yield even after pesticide application, according to Bill Hutchison, a professor and extension entomologist with the University of Minnesota.

Meanwhile, on the front lines, Nelson reports warmer winters and earlier springs at Untiedt’s. These changes have resulted in earlier arrivals of fruit flies to the farm’s strawberry, raspberry, and tomato crops. Despite conventional wisdom that their June-bearing strawberries would be safe, Nelson reports, “That’s not the case. We’ve found them in our June-bearing strawberries.”

In response to the persistent pests, Nelson and his team have deployed pesticides and traps, invested considerable time hunting down the minuscule bugs, and utilized protective netting and plastic coverings. However, these methods have their shortcomings. Pesticides can exterminate beneficial insects, halt farm operations during spraying, and netting can be challenging to set up, while plastic coverings risk overheating crops.

The potential solution still needs further research and regulatory approval before it can be field-tested. Considerations include regional genetic variations within species and the ecological impact of interspecies interactions. Even with these hurdles, the prospect of a successful bio-control approach is favorable compared to pesticide use, which carries significant environmental consequences.

While waiting for these new solutions, Nelson continues his work on the farm, concerned for the future. He wonders, “What will this mean for the next generation? If we lose our berry sales, it would significantly impact our farm.”

Follow Melina Walling on Twitter at @MelinaWalling.

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Frequently Asked Questions (FAQs) about Fruit fly sterilization

More about Fruit fly sterilization

• Spotted Wing Drosophila
• Gene Drive
• Genetic Pest Control
• North Carolina State University
• Proceedings of the National Academy of Sciences
• University of Minnesota – Entomology