How Rotting Food in the Kitchen and a Whiff of Vinegar Led to a ‘Happy’ Agricultural Accident

The surprise discovery of a natural fruit fly repellent could lead to new controls for one of New Jersey’s biggest blueberry pests

Rutgers scientists have identified natural repellents against an invasive blueberry pest, a scientific breakthrough that was accidentally discovered when fruit flies invaded their laboratory.

The accident, more than a decade in the making, could one day transform how commercial crops are protected.

“As a kid, this is what I thought science was – you stumble on something and go, ‘Eureka!’” said Beth Ferguson, a postdoctoral researcher at the Rutgers Philip E. Marucci Center for Blueberry and Cranberry Research, and lead author of the study, published in the journal Applied and Environmental Microbiology. “Of course, that doesn’t happen most of the time, which is why I call this a very happy accident.”

Each summer, Ferguson and colleagues conduct research on an invasive fruit fly, the spotted-wing drosophila (Drosophila suzukii). Found in New Jersey in 2011, the fly is one of the biggest threats to commercial fruit production, particularly soft-fleshed fruit such as blueberries.

Unlike other Drosophila flies, which lay eggs on and feed on rotten fruit, the spotted-wing drills into intact, ripening fruit, using a saw-like tube to deposit its eggs. The fly larvae hatch and destroy the fruit from within. 

The resulting spoilage is costly to producers. In 2025, New Jersey growers produced 47.5 million pounds of blueberries, with a production value of more than $94 million. The state consistently ranks among the top blueberry producers nationwide, and blueberries are New Jersey’s No. 1 crop. 

But growers spend heavily on chemical insecticides, which do not always provide complete control and can harm nontarget organisms.

In their lab, Ferguson and colleagues breed colonies of spotted wing to test new, nonchemical management strategies. And nearly every summer, something curious happened to the colonies they raised: the enclosure, located close to the research center’s kitchen, would be invaded by a common fruit fly, D. melanogaster, which led to die-offs of the spotted-wing flies.

With thousands of flies in these containers, not even a skilled researcher can differentiate them with the naked eye, said Ferguson. But fly colonies do have different smells, and when enough D. melanogaster flies had reproduced to outnumber the spotted wing flies, the scent was unmistakable. 

“We’d notice a smell change, going from a spotted wing-smell – like corn meal – to a very heavy vinegar decay odor, which is the telltale smell of melanogaster,” said Ferguson.

In nature, the two flies often avoid competition. But the accident of placing the enclosure near the kitchen, where melanogaster flies would feed on rotting fruits, fueled a hidden rivalry.

Ferguson noticed that as the vinegar smell intensified, a strange film-like deposit was forming on the flies’ food source. As with dogs marking territory, fruit flies mark food and egg-laying areas by depositing fecal and gut fungi. Ferguson swabbed the film and worked with colleague James Polashock from the United States Department of Agriculture (USDA) to identify the yeast.

She and lab director Cesar Rodriguez-Saona then reached out to Jennifer S. Sun, an assistant professor in the Department of Biochemistry and Microbiology at Rutgers-New Brunswick, and a coauthor on the paper. 

Sun and undergraduate researcher Tia Hart ran a series of tests to confirm the spotted wing’s aversion to melanogaster’s fungi and how exposure affected the fly’s egg-laying preferences. “Our first question was whether this is truly repulsive to spotted wing,” said Sun. “The answer came quick.”

What she found was striking: The yeast “elicited aversive responses” in spotted wing while remaining attractive to melanogaster. Spotted wing flies also laid far fewer eggs after having encountered the yeast. 

Further testing will be needed to assess how the lab-produced compound might behave in nature. Ferguson said it can take years from discovery to gain regulatory approval. 

But already, the eureka moment is paying dividends. 

“I've been using it as a model for my students, explaining that when an experiment yields unexpected results, they shouldn’t assume that they did something wrong,” said Sun. “Instead, they could ask why it's happening, and if there's another phenomenon we could be studying. When the scientific process is used in experimentation, the result could be a very fruitful project like this one.”

Explore more of the ways Rutgers research is shaping the future.

This work was funded by several grants, including $2.1 million (award number R35GM165839) from the National Institute of General Medical Sciences of the National Institutes of Health. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.