According to Gram Research analysis, a 2026 study of over 1,600 insects across Italian mountain parks found that 76% of honeybees, wild bees, and hoverflies carried at least one disease, with deformed wing virus and chronic bee paralysis virus being most common. Hoverflies—non-bee insects that pollinate plants—also harbored bee diseases, sometimes exclusively. Disease rates were highest at lower elevations and in areas with sparse vegetation, suggesting environmental conditions significantly influence pollinator disease risk.
Scientists studied over 1,600 insects across four mountain parks in Italy to understand how diseases spread between honeybees, wild bees, and hoverflies. They found that three-quarters of the insects carried at least one disease, including viruses and parasites. Surprisingly, hoverflies—insects that look like bees but aren’t—were catching bee diseases too. The research shows that pollinator diseases spread more easily in lower elevations and less vegetated areas, and peak during summer months. This discovery suggests we need to watch all pollinator health more carefully, not just honeybees, to protect the insects that help our crops and plants grow.
Key Statistics
A 2026 analysis of 1,600 insects from 54 species across four Northern Italian mountain parks found that 76.3% carried at least one bee-associated pathogen, including viruses, parasites, and other microorganisms.
In the same study, deformed wing virus and chronic bee paralysis virus were the most prevalent pathogens, with hoverflies harboring sacbrood virus exclusively in three of the four parks, suggesting these non-bee insects serve as disease reservoirs.
Research showed that pathogen prevalence decreased significantly at higher altitudes and in areas with denser vegetation, indicating that environmental factors substantially influence disease spread among wild pollinators.
July showed peak pathogen abundance across all insect species studied, while hoverflies exhibited lower overall disease occurrence than bees but carried multiple infections simultaneously when infected.
The Quick Take
- What they studied: Whether diseases that affect honeybees also infect wild bees and hoverflies, and what environmental factors influence disease spread in mountain ecosystems.
- Who participated: Over 1,600 individual insects from 54 different species, including honeybees, wild bees, and hoverflies, collected from four National Parks in the mountains of Northern Italy at different elevations.
- Key finding: About 76% of all insects tested carried at least one disease, with deformed wing virus and chronic bee paralysis virus being the most common. Hoverflies—which aren’t bees but look similar—also carried bee diseases, sometimes exclusively.
- What it means for you: Pollinator diseases aren’t just a honeybee problem. Wild insects that pollinate our gardens and crops are getting sick too, especially in lower-elevation areas with less plant coverage. This suggests we need broader strategies to protect all pollinators, not just managed honeybees.
The Research Details
Researchers collected insects from four mountain parks in Northern Italy, sampling across different elevations and habitat types. They caught over 1,600 individual insects representing 54 different species—honeybees, wild bees, and hoverflies (insects that mimic bees but belong to a different family). Each insect was tested for 10 different diseases using laboratory methods that can detect viruses, parasites, and other pathogens.
The team then analyzed how environmental factors like altitude, plant density, season, and insect characteristics influenced disease presence and abundance. They looked at patterns across the four parks to understand what conditions made diseases more or less common. This approach allowed them to see the big picture of disease circulation in wild pollinator populations across a real landscape.
This research design is important because it moves beyond studying just honeybees in managed hives. By sampling wild insects across natural mountain ecosystems with varying conditions, the researchers could see how diseases actually spread in nature. Testing multiple insect species together revealed that diseases jump between different types of pollinators, which previous studies focusing only on honeybees might have missed. Understanding environmental drivers of disease helps identify which areas and conditions pose the greatest risk to pollinator health.
The study’s strength lies in its large sample size (over 1,600 insects), diverse geographic sampling across four parks, and testing for multiple pathogens simultaneously. The researchers used established laboratory detection methods and analyzed data with statistical approaches that account for environmental variables. However, the study is observational rather than experimental, meaning it shows correlations but cannot prove that environmental factors directly cause disease differences. The findings are specific to Northern Italian mountain ecosystems and may not apply identically to other regions.
What the Results Show
The most striking finding was that 76.3% of all insects tested—whether honeybees, wild bees, or hoverflies—carried at least one disease. Two viruses dominated: deformed wing virus (DWV) appeared in many insects, and chronic bee paralysis virus (CBPV) was also very common. A parasite called Nosema ceranae and another virus called black queen cell virus (BQCV) were the next most frequent infections.
Hoverflies, which are not true bees but important pollinators that look similar, harbored multiple diseases. Notably, sacbrood virus was found exclusively in hoverflies from three of the four parks, suggesting these insects may serve as disease reservoirs. This was surprising because hoverflies are often overlooked in pollinator health monitoring.
Environmental conditions strongly shaped disease patterns. Insects living at higher elevations had fewer diseases than those at lower elevations. Areas with denser vegetation (measured by a vegetation index) showed lower disease rates. July was the peak month for disease abundance across all insects, suggesting summer conditions favor pathogen spread. Among hoverflies specifically, whether they had one or two generations per year, their larval diet, and their sex all influenced disease risk.
The research revealed that different insect species had different disease susceptibilities. Hoverflies generally had lower disease occurrence than bees, but when they did carry pathogens, they often carried multiple infections simultaneously. The diversity of pathogens detected—10 different types across the insects—indicates complex disease circulation networks in mountain ecosystems. Seasonal patterns showed that while July peaked, disease presence varied throughout the year, suggesting different pathogens have different seasonal dynamics.
Previous research focused heavily on honeybee diseases in managed colonies, where deformed wing virus and Nosema ceranae are well-documented problems. This study confirms these pathogens are widespread in wild populations too, but extends understanding by showing they’re not limited to honeybees. The finding that hoverflies carry bee pathogens is relatively novel and suggests disease ecology is more interconnected than previously appreciated. The environmental drivers identified—altitude and vegetation density—align with some previous studies but provide new quantitative evidence from a natural landscape.
The study is observational, so it shows which conditions correlate with more disease but cannot prove those conditions cause disease. The research was conducted in Northern Italian mountains, so results may not apply to other regions with different climates, elevations, or insect communities. The study captured a snapshot in time; longer-term monitoring would reveal whether disease patterns change year to year. The researchers didn’t investigate why hoverflies carry bee pathogens—whether they acquire them from bees, share food sources with infected bees, or through other mechanisms remains unclear.
The Bottom Line
Monitor wild pollinator populations for disease, not just managed honeybees (high confidence). Protect vegetation in lower-elevation areas where disease risk is highest (moderate confidence). Consider hoverflies and other non-bee pollinators in pollinator health surveillance programs (moderate confidence). Avoid practices that reduce plant diversity or density in pollinator habitats (moderate confidence). Further research is needed before making specific management recommendations for reducing disease spread.
Beekeepers should care because wild bees near their hives may transmit diseases to managed colonies. Farmers and gardeners should care because wild pollinators are essential for crop production and plant reproduction. Conservation managers should care because disease is an additional threat to wild pollinator populations already facing habitat loss and pesticides. Policymakers should care because pollinator health affects food security and ecosystem function. People living in or managing mountain ecosystems should be particularly attentive given the documented disease circulation.
Disease patterns appear to shift seasonally (within months), with peaks in summer. Longer-term changes in disease prevalence would likely take years to observe. If management practices are implemented to increase vegetation or reduce other stressors, improvements in pollinator health might take one to several years to become apparent.
Frequently Asked Questions
Can hoverflies catch diseases from honeybees?
Yes. A 2026 study of 1,600 insects found that hoverflies carry bee pathogens including deformed wing virus, chronic bee paralysis virus, and sacbrood virus. Hoverflies even harbored sacbrood virus exclusively in some areas, suggesting they acquire and may transmit bee diseases.
What environmental factors reduce disease in wild pollinators?
Higher elevation and denser vegetation significantly reduce disease rates in wild pollinators. The 2026 study found pathogen prevalence decreased with altitude and vegetation index values, suggesting that protecting plant diversity in lower-elevation areas helps protect pollinator health.
When is disease most common in wild pollinators?
July showed peak pathogen abundance across all insect species in the 2026 study. Disease rates varied seasonally, suggesting different pathogens thrive at different times of year, with summer conditions generally favoring pathogen spread.
Why should we care about wild bee diseases if we have managed honeybees?
Wild pollinators like bees and hoverflies are essential for crop production and plant reproduction. The 2026 study found 76% carry diseases, and wild insects can transmit pathogens to managed colonies. Protecting wild pollinator health protects food security and ecosystem function.
Are mountain ecosystems safer for pollinators than lowland areas?
Yes, according to the 2026 research. Higher-altitude mountain areas showed significantly lower disease prevalence in pollinators compared to lower elevations, suggesting altitude provides some natural protection against pathogen spread.
Want to Apply This Research?
- Track weekly observations of pollinator abundance and diversity in your garden or local area, noting the month and vegetation density. Compare your observations across seasons to see if summer shows more insect activity (when disease peaks) and whether areas with denser plants have more pollinators.
- Increase native plant diversity and density in your garden or yard to create healthier habitat for wild pollinators. The research shows that areas with higher vegetation index values have lower disease rates, so planting native flowers, shrubs, and trees can help protect local pollinator populations.
- Establish a monthly pollinator monitoring routine, photographing or counting bees and hoverflies you observe. Track this data by season and note the vegetation density of your observation area. Over time, you’ll build a personal dataset showing how your habitat changes correlate with pollinator presence, mirroring the research’s findings about environmental influences on pollinator health.
This research describes disease prevalence in wild pollinator populations and should not be interpreted as medical advice for managing honeybee colonies or treating specific diseases. Beekeepers should consult with veterinary entomologists or bee health specialists for colony management decisions. The findings are specific to Northern Italian mountain ecosystems and may not apply to other regions. This study is observational and shows correlations, not direct causation. Anyone concerned about pollinator health should consult local agricultural extension services or conservation experts for region-specific guidance.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.