Researchers from the University of Exeter have unveiled alarming findings about the dietary habits of Asian hornets, highlighting their extensive predation on over 1,400 species of insects, many of which are key pollinators. The study, published on March 4, 2025, in the journal Science of The Total Environment, used innovative deep sequencing techniques to analyze hornet larvae from various regions, including France, Spain, Jersey, and the UK, raising significant concerns about the ecological impact of these invasive predators as they spread across Europe.
The Asian hornet, recognized for its distinctive yellow legs and aggressive nature, has earned its reputation as one of the most invasive species since sneaking its way to France two decades ago via cargo shipments from China. Since then, it has expanded its territory across much of western Europe, causing devastation to honey bee populations—one hornet can kill up to 50 bees per day, endangering entire colonies.
According to Siffreya Pedersen, the lead author of the study, "Asian hornets were known to prey on honeybees, but until now, the full range of their diet hadn’t been tested. The diet varied strongly over the seasons and between regions, showing they are highly flexible predators." This adaptability not only showcases their diversity but also raises questions about the potential threats they pose to native insect populations already struggling due to habitat destruction, chemical pollution, and land use changes.
The researchers collected and analyzed samples from the guts of more than 1,500 Asian hornet larvae gathered from 103 nests. The results were surprising, with 1,449 different prey species identified. Over half of these could be classified as specific species, indicating the broad ecological footprint of the Asian hornet. Among the top 50 most commonly identified prey species, 43 are known to visit flowers, such as the European honey bee, buff-tailed bumblebee, and red-tailed bumblebee—central figures in pollination processes throughout Europe.
Pedersen commented on the broader ecological ramifications, mentioning, "Most insect populations are declining due to factors such as habitat destruction and chemical pollution. The spreading area inhabited by Asian hornets poses an extra threat." The ramifications of this invasive species becoming firmly rooted could prove detrimental, particularly as it competes with native species for food sources and contributes to declining biodiversity.
The role of insects extends beyond food chains; they are integral to facilitating ecosystems—performing tasks like pollination, pest control, and decomposition. The significance of this research lies not only in the immediate threats to honey bees, which are already suffering declines, but also to the entire biodiverse web of life supported by these pollinators. Worldwide, insect populations are under enormous pressure—this study emphasizes the need for increased awareness and protective measures.
Asian hornets have already established nests throughout the UK, with authorities actively seeking to destroy them each year to prevent their establishment. The year 2016 marked the introduction of these invasive predators to the UK, and the threat has only intensified ever since, with 44 confirmed sightings reported throughout 2024, especially concentrated within Kent and East Sussex.
The deep sequencing method applied by researchers is groundbreaking as it allows for comprehensive prey analysis. By genetically analyzing the larval samples, the team could trace the food consumed by hornets, providing unprecedented insight. Though the study confirmed the European honey bee as the most common prey type—present in every sampled nest—the hornets' diet was significantly broader than previously understood.
This widened diet, coupled with the hornets’ predatory nature, suggests potential ramifications beyond just decreased honey bee populations. It poses serious questions for agricultural sustainability and the stability of ecosystems at large. European agriculture relies heavily on various pollinators for crop production, and with key species declining, farmers and conservationists alike must grapple with the impending challenges.
Dr. Peter Kennedy from Exeter's Environment and Sustainability Institute reinforced the significance of these findings, stating, "Our study provides important additional evidence of the threat posed by Asian hornets as they spread across Europe." He highlights the urgency for targeted efforts to contain this invasive species and protect vulnerable native insects.
While the full extent of the threat remains to be seen, the study acts as both a warning and a call to action. With much of Europe's insect populations already under pressure, the inclusion of Asian hornets as another variable complicates the ecological fabric—one that's already becoming frayed. Active monitoring and preventive strategies will be necessary to mitigate the impacts of this invasive species on ecosystems across the continent.
Moving forward, ensuring the balance of our ecosystems must become our collective priority, addressing not only immediate threats like the Asian hornet but fostering environments where native species can thrive alongside our agricultural needs.