Researchers turn to sterilization of fruit flies in battle against berry damage

Paul Nelson and his team run a farm in Minnesota which has been greatly affected by the invasive fruit fly known as the spotted wing drosophila. The pest ruined over 50% of the berries at the farm at one point.

In recent years, Nelson and his team have been able to reduce their losses to 5%. However, this has come at a high cost both financially and in terms of labor.

To combat this issue, researchers are now focusing on sterilizing the fruit flies, which could potentially help to control their population and reduce the amount of damage they cause.

Paul Nelson, who heads the grower team at Untiedt’s, a fruit and vegetable operation located approximately an hour away from Minneapolis, emphasizes the importance of dedicating time and effort to managing the invasive fruit fly pest known as the spotted wing drosophila.

According to Nelson, failure to address this issue can result in the pest taking over a farm.

He describes the pest as labor-intensive and challenging to manage, often leading to high costs in the pursuit of reducing losses.

Growers such as Nelson may eventually have a new approach to combating the invasive fruit fly pest thanks to research being conducted at North Carolina State University.

These pests lay their eggs in berries and the subsequent larvae can cause significant damage. It is estimated that the flies cost growers millions of dollars annually.

Researchers at NC State University are currently working on a gene drive approach to managing the pests by manipulating their DNA to create sterile offspring. This methodology significantly reduces the chance of a population rebound, and if successful, could be a game-changer for farmers affected by these pests.

The researchers’ findings were recently published in the Proceedings of the National Academy of Sciences. The study details a gene drive approach in which the insects’ DNA was manipulated to produce sterile female offspring.

Through mathematical modeling, the researchers determined that releasing one modified fruit fly for every four non-modified flies and repeating this every two weeks could lead to a significant reduction in the population size in as little as five months. In fact, up to 99% of the offspring could inherit the desired sterility trait when bred with non-modified flies. These findings suggest that this approach could be a promising solution for managing pest populations like the spotted wing drosophila.

The concept of using genetically modified insects for pest control purposes is not entirely new. For instance, genetically modified mosquitoes have already been released, which mate with the existing population and produce offspring that die before they mature into adults to restrict populations and help to curb the spread of insect-borne diseases such as yellow fever, dengue, and Zika viruses.

However, utilizing this technology in agriculture has not been as widespread as in other sectors, mainly because conventional pesticide use has been less expensive and easier to implement. Nonetheless, the new research on gene drive manipulation for controlling pests in crops, such as the spotted wing drosophila, indicates that there could be a safe and effective alternative to conventional pesticide use in agriculture.

According to Max Scott, a co-author of the paper and a professor of entomology, some methods of releasing genetically modified insects for pest control could become considerably expensive, particularly if the process has to be repeated numerous times before the pests are effectively eliminated.

However, the gene drive method utilized by Scott’s team has the potential to facilitate sterility more efficiently and quickly throughout successive generations of insects. Therefore, fewer instances of releasing modified bugs might be required over time. The gene drive approach is designed to enable the inheritance of particular desirable traits across successive generations of insects, resulting in a higher chance of successful pest population control.

Max Scott expressed his excitement about the effectiveness of the gene drive approach and its potential to combat the spotted wing drosophila pest problem efficiently.

The success of the gene drive approach could be an essential addition to farmers’ pest management techniques as these pests can significantly impact crop yield, even after pesticide use. Bill Hutchison, a professor and extension entomologist at the University of Minnesota, emphasized the growing threat of pests with climate change. The warming winter temperature is allowing invasive species like the spotted wing drosophila to survive and extend their range, increasing the need for effective pest control strategies.

Paul Nelson, the head grower at Untiedt’s farm, has observed the effects of climate change on the farm’s crops, including warmer winters and earlier springs. He noted that fruit flies have been appearing earlier each year to the farm’s approximately 35-acre plot containing strawberries, raspberries, and tomatoes.

The spotted wing drosophila, in particular, was initially believed to be absent in June-bearing strawberries due to the early harvesting time, but Nelson’s observations have proven this to be untrue. He highlights the importance of innovative pest management techniques, such as the gene drive approach developed by the researchers, to combat this increasingly prevalent pest issue in agriculture.

To control the spotted wing drosophila, Nelson and his team have adopted various measures such as the use of pesticides and traps, as well as spending significant time searching for these tiny bugs. Farmers like Hutchison also suggest the use of ventilated netting or plastic coverings to create a type of greenhouse over their fruits. However, conventional techniques such as spraying pesticides can harm beneficial insects and disrupt farm operations if farmers need to halt berry-picking for a few days. Netting can also be labor-intensive to set up, and plastic coverings can overheat crops, leading to other complications.

Therefore, gene drive technology could provide an effective and sustainable solution for managing these pests while still maintaining beneficial insect populations and avoiding disruptions to farm operations.

Luciano Matzkin, an associate professor of entomology at the University of Arizona, studies drosophila and other pest species and often considers their impact on agriculture. According to Matzkin, Scott’s team’s approach of sterilizing females to control the pests has effectively resolved a common issue that arises with gene drive technology. Some gene mutations can occur randomly and get passed down, thwarting the scientists’ intended outcome.

Lyric Bartholomay, a professor at the University of Wisconsin-Madison, also agrees that developing increasingly tailored genetic approaches will be crucial for pest control in the future, particularly as insecticide resistance continues to be a challenge. The utilization of advanced genetic techniques like gene drive technology can provide new and innovative options for farmers and researchers to address the pest issues that pose serious risks to crops and human health.

Although the gene drive technology shows promising results for controlling invasive pests like the spotted wing drosophila, there is still much work to be done before it is practically applied.

Scott and his team will continue laboratory trials to verify their mathematical modeling and will have to undergo regulatory procedures before progressing to field testing. Additional research will be necessary to monitor the regional genetic variation within the same species and the potential ecological impacts of these modifications on other species. Both Scott and Matzkin emphasize that this is an essential consideration in the development of effective and sustainable pest control strategies.

Luciano Matzkin believes that if a bio-control approach could be developed without negative environmental risks, it would always be a preferable option to conventional pesticides. Pesticides pose significant environmental impacts and cost considerations. Matzkin added that entomology departments across the country are currently investigating the biology and ecology of insects in tandem with other researchers developing transgenic approaches to population control for a range of pests.

The goal is to develop effective, sustainable, and low-cost solutions that can reduce the dependency on expensive chemicals while minimizing environmental risks. Bio-control approaches like gene drives hold significant promise in this regard, as Scott and his team have demonstrated in their study, but continued research is necessary to verify efficacy and safety in field conditions.

As researchers continue to develop solutions to manage pests, farmers like Paul Nelson remain uncertain about the future. Nelson, who farms with his son and manages crops susceptible to damage from the spotted wing drosophila, is concerned about how developments like climate change and increases in pest resistance will impact his business.

Although researchers and experts may provide guidance, farmers also closely monitor the changes happening in their fields and weigh the potential effects on future generations. The loss of revenue due to a decrease in sales of berry crops could have significant financial implications for farms like Nelson’s, highlighting the importance of effective pest management techniques that can sustainably support crop production.