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GHENT, Belgium — It turns out that bugs like their beer too — and that could be surprisingly great news for exterminators. Researchers have discovered that different species of fruit flies have distinct preferences when it comes to beer. This discovery, far from being a mere curiosity, could soon lead to better pest control in agriculture.
A study published in the journal iScience reveals that two closely related fruit fly species, Drosophila melanogaster and Drosophila suzukii, are attracted to different types of beer based on their unique aroma profiles. This preference aligns with their natural behaviors and habitats, offering valuable insights into how these insects locate food sources and potential breeding grounds.
D. melanogaster, the common fruit fly often found in households, showed a preference for darker beers like brown ales and dubbels. These beers typically have strong aromas associated with fermentation, mirroring the fly’s attraction to overripe and rotting fruit. In contrast, D. suzukii, also known as the spotted wing drosophila, favored lighter beers such as blondes and tripels, which have more floral and hoppy scents reminiscent of fresh, ripening fruit. This distinction is crucial because while D. melanogaster is generally harmless, D. suzukii is a serious agricultural pest.
“Across the world, D. suzukii causes millions in damages in fruit farming. Because of climate change, the species is expanding its territory, with enormous economic and ecologic consequences,” explains Maria Dzialo, the study’s first author, in a statement.
The research team, composed of scientists from the VIB-KU Leuven Center for Microbiology in Belgium and the Max Planck Institute for Chemical Ecology in Germany, along with the Belgian company BioBest, used an innovative approach to uncover these preferences. They selected 45 different Belgian beers with diverse aroma profiles, based on a detailed chemical analysis of 250 beers. The flies were then given choices between these beers and a “blank” beer with minimal aroma.
By analyzing the chemical composition of the preferred beers and correlating it with fly behavior, the researchers identified specific compounds that attract or repel each species. For instance, yeast-produced fragrances like pentyl acetate (which smells like banana) and ethyl acetate (a sweet, fruity scent) were more attractive to D. melanogaster. On the other hand, plant-derived scents such as linalool (citrusy and sweet) and geraniol (floral and fruity) were more appealing to D. suzukii.
“We observed stronger brain activity in D. melanogaster than in D. suzukii when exposed to geraniol. This activity occurred in a brain region responsible for aversion to scent,” notes Silke Sachse from the Max Planck Institute for Chemical Ecology. “This suggests that geraniol could serve as a deterrent for D. melanogaster but won’t have a repellent effect on D. suzukii.”
So, are we soon to see beer on the shelves alongside common insect repellants? Not exactly, but there’s certainly some inspiration here to create products based off of the brews’ aromas.
“By understanding which substances attract specific insects, we can develop targeted traps. This benefits both consumers and farmers while minimizing impact on other, beneficial insects,” adds Verstrepen. “Tests in industrial greenhouse settings already confirmed that we can compose mixes of a few beer aroma compounds that attract more D. suzukii than D. melanogaster, showing the potential of our findings for pest control in biological agriculture.”
The study also suggests more natural methods of pest control.
“Our experiments suggest that certain plants such as laurel and thyme could be deployed strategically to lure pests like D. suzukii away from fruit plants without using chemical agents,” Verstrepen notes.
It’s quite fascinating to see how a basic scientific inquiry into seemingly trivial matters — like which beers fruit flies prefer — can lead to practical applications with significant real-world impact. By leveraging the natural preferences of these insects, we may be able to develop more targeted, environmentally friendly pest control methods, potentially reducing the need for harmful pesticides in agriculture.
As Verstrepen humorously adds, “And of course, it’s also good to know which beers won’t attract flies when you’re out for a drink.”
Paper Summary
Methodology
The researchers used a clever experimental setup to test fly preferences. They created small traps using plastic containers with funnel-shaped entrances. These traps were filled with either test beer or a “blank” beer with minimal aroma. The traps were placed in enclosed arenas, and flies were released to see which traps they preferred. By counting the number of flies in each trap after a set time, the researchers could calculate how attractive each beer was.
They also used sophisticated chemical analysis techniques to measure the concentrations of various aroma compounds in each beer. This allowed them to correlate specific chemical components with fly behavior.
Key Results
The study found clear differences in beer preferences between the two fly species. D. melanogaster showed a stronger overall attraction to beer and preferred darker varieties with strong yeast and malt aromas. D. suzukii, on the other hand, was more drawn to lighter beers with floral and hoppy scents.
When testing individual chemical compounds, the researchers identified several that were specifically attractive or repellent to each species. For example, acetate esters (fruity smells) were more appealing to D. melanogaster, while terpenes (plant-derived scents) were more attractive to D. suzukii.
Study Limitations
The experiments were conducted in controlled laboratory conditions, which may not fully reflect real-world scenarios. Additionally, the concentrations of compounds tested were based on those found in beer, which might differ from levels encountered by flies in natural settings. The researchers also focused on a limited number of compounds, and there may be other important attractants or repellents not identified in this study.
Discussion & Takeaways
This research highlights the complex relationship between insect behavior and chemical cues in their environment. It demonstrates how closely related species can evolve different sensory preferences that align with their ecological niches. The study also showcases the potential of using complex natural mixtures like beer to identify behaviorally relevant compounds.
From a practical standpoint, the findings open up new possibilities for developing more targeted and effective pest control strategies. By using specific combinations of attractants and repellents, it may be possible to create traps that selectively capture harmful pests while sparing beneficial insects.
Funding & Disclosures
The study was supported by various research institutions and funding agencies, including KU Leuven, the Flemish Institute for Biotechnology (VIB), and the Max Planck Society. One of the authors is employed by Biobest, a company that produces commercial insect traps. This connection is disclosed in the paper to ensure transparency regarding potential conflicts of interest.
