Unlocking new routes to pest control: How bioengineered flies could transform agriculture

by Carolyn Bernhardt

December 12, 2024

scientist in a lab coat poses for a photo next to a high-tech camera system
Ratnasri Pothula, PhD, with a machine learning vision system used to observe SWD. Credit: Domini Brown

 

The spotted wing drosophila (SWD, Drosophila suzukii), a small but destructive fruit fly, is a significant threat to crops like cherries, blueberries, and strawberries. This pest causes more than $700 million in agricultural damage yearly, frustrating farmers and often forcing them to use chemical pesticides, which can harm beneficial insects and the environment. But what if there was a way to control SWD populations without broad-spectrum chemicals? 

With funding from the Minnesota Invasive Terrestrial Plants and Pests Center (MITPPC), University of Minnesota researchers are developing a cutting-edge solution: genetically engineered flies that disrupt SWD reproduction, offering a safer and more targeted pest control method.

Turning pests into pesticides

“Think of it like a key and lock,” says Ratnasri Pothula, PhD, a postdoctoral associate in the College of Biological Sciences leading this research. “If you change the key or the lock even slightly, they no longer fit together. We apply the same principle in SWD. By modifying their DNA, we create flies that, when released, produce no viable offspring.”

two fruit flies under a microscope with one showing green influoresence
Researchers add a fluorescent gene to transgenic fruit flies as a visible marker to track offspring that inherit the transgenic locus. Top: wild type fly without fluorescence; bottom: transgenic fly with fluorescence. Credit: Ratnasri Pothula

This method is known as genetic biocontrol. It essentially turns the pest species into its own pesticide. Engineered male flies are released into the wild, where they mate with wild females. However, genetic modifications prevent the resulting offspring from surviving, gradually reducing the pest population over time. Unlike chemical pesticides, which often affect non-target species, this method is highly specific. It ensures that other beneficial insects such as bees and butterflies remain unharmed.

This more novel approach has similarities to the tried-and-true sterile insect technique (SIT). SIT is a decades-old pest management strategy that successfully eradicated pests like the New World screwworm fly from large regions in South America. SIT relies on sterilizing insects using radiation, but genetic biocontrol improves on this method by engineering a self-sustaining synthetic species. Researchers can breed engineered flies in the lab and release them over and over again, providing a lasting solution. In contrast, insects sterilized with radiation cannot reproduce, which offers only a short-term solution before the effects diminish.

two images showing a spotted wing drosophila in normal light (left) and with cyan fluorescence (right)
Left: SWD in white light; right: the same SWD showing cyan fluorescence. Credit: Nathan Feltman

Pothula works in the lab of Michael Smanski, PhD, an associate professor and associate head of research in the Biochemistry, Molecular Biology, and Biophysics department in the College of Biological Sciences. He says, “There are some insects where the dose of radiation that you need to sterilize them is so close to the dose needed to kill them that it's a difficult needle to thread. Whereas we've found a way to genetically hardwire that incompatibility so that any wild female that mates with one of our engineered males won't have offspring.” 

Challenges in the lab and field

While the concept is promising, translating it into reality involves numerous challenges. First, the team had to test their methods in the lab on a model organism, Drosophila melanogaster. Small genetic differences between the two species have presented some unexpected hurdles. “Moving from a lab model to an actual pest species is a major leap,” said Smanski. “We’ve had to tweak component parts to make sure they work in SWD, not just in the model organism.”

researcher sits in front of a computer screen showing flies under a camera
In the lab, Pothula uses a high-tech vision system to record and analyze live fly behaviors. Credit: Domini Brown

Beyond lab challenges, the researchers must consider how the flies will perform in real-world conditions. Flies reared in a controlled lab environment may adapt to those conditions and lose traits necessary for survival and competition in the wild. To address this, the team is developing systems to test the engineered flies under various temperatures, humidity levels, and environmental stressors.

“We’re working to ensure the flies can compete with wild populations and maintain their genetic modifications in the field,” said Pothula. “This includes using computer vision systems to analyze behaviors like flight and mating preferences.”

As with any genetic engineering technology, this research can spark public skepticism and safety concerns. “As technology developers, we spend a lot of time making sure the system works,” says Smanski. “But we spend even more time figuring out if it breaks, how it breaks, and how to make it more resilient. Our goal is to create something safer than current pest control methods.”

With this in mind, the team has conducted extensive engagement with regulators, Indigenous groups, and the public to gauge their perceptions of genetic biocontrol, comparing it to traditional chemical and physical control strategies. “We've found strong public support for this approach, as people generally understand the technology at a high level,” Smanski says. “There seems to be a significant appetite for the use of new technologies in pest control.”

Expanding the pest management toolbox 

The research is still in development, but its next steps are clear. The team aims to integrate all the successful components into a complete genetic biocontrol system for SWD. From there, they will conduct further testing in environmentally relevant conditions and collaborate with regulators, Tribal nations, and the public to ensure the technology is safely implemented.

Smanski emphasized the importance of a careful, step-by-step approach: “We start with designs on the computer, validate components in the lab, and then test them under conditions closer to the real world. By doing this, we build a robust system that’s both effective and safe.”

By creating pest-specific bioengineered solutions, the team hopes to reduce reliance on chemical pesticides and offer a versatile approach to managing invasive species and agricultural pests. For Pothula and Smanski, one of the most exciting aspects of this research is its potential applications beyond SWD, including invasive carp and disease-carrying mosquitoes.

“This technology is not limited to SWD,” said Pothula. “It can be applied to any sexually reproducing organism. That’s the strength of this work—it’s scalable and adaptable.”

According to Smanski, “The appetite for these technologies is growing, and with continued effort, we can deliver pest control strategies that are safer for the environment, people, and agriculture.”

More information


Research from the Minnesota Invasive Terrestrial Plants and Pests Center is supported by the Environment and Natural Resources Trust Fund, as recommended by the Legislative-Citizen Commission on Minnesota Resources.

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