Neonicotinoids and Bees: What Company and Independent Studies Show, and How Rules Differ in 2026

In 2017, reports revealed that field studies funded by Bayer and Syngenta, the main makers of neonicotinoid insecticides, had found evidence of harm to honey bees at high exposure levels, findings the companies said did not reflect typical farming conditions. The reports added fuel to a debate that had been building for years: are neonicotinoids, the world’s most widely used class of insecticides, contributing to declines in bees and other pollinators?

Since then, major independent studies have been published, the European Union has banned outdoor use of three neonicotinoids, and U.S. regulators and states have taken their own steps. This article explains what neonicotinoids are, what the research shows about their effects on bees, how regulations differ, and what gardeners and consumers can do.

Do neonicotinoids kill bees? They are one of several major pressures on bees, not the sole cause of decline. Company-funded studies tended to downplay harm, while independent field research found neonicotinoids can impair bee foraging, reproduction, and colony health, especially alongside the varroa mite, poor nutrition, and habitat loss. The EU restricted outdoor neonicotinoid use; the US has acted more slowly. Protecting bees requires addressing pesticides and these other stressors together.

What Are Neonicotinoids?

Neonicotinoids are a widely used class of insecticides, chemically related to nicotine, often applied as seed coatings so the whole plant becomes toxic to insects, including pests and sometimes pollinators. Neonicotinoids, sometimes called neonics, are insecticides chemically related to nicotine. They act on insects’ nervous systems, binding to receptors that, in insects, lead to paralysis and death. Introduced in the 1990s, they became the most widely used insecticides in the world because they are effective at low doses and less acutely toxic to mammals than many older insecticides. Common neonicotinoids include imidacloprid, clothianidin, thiamethoxam, acetamiprid, and thiacloprid.

Neonicotinoids are systemic: when applied to seeds, soil, or foliage, they are absorbed and distributed throughout the plant, including leaves, flowers, pollen, and nectar. In the United States, most corn and soybean seeds and many other crop seeds have been sold pre-coated with neonicotinoids, often regardless of whether pest pressure justifies it. They are also used on ornamental plants, lawns, and in flea treatments for pets. Because they are water-soluble, they can move into soil and waterways, where they may affect aquatic insects.

What Did Company-Funded Studies Claim?

Industry-funded studies tended to find little harm to bees at field-realistic doses, but critics noted limitations in their design and the influence of funding on how results were framed. Under European rules, Bayer and Syngenta were required to conduct field studies on their neonicotinoids’ effects on bees. In 2017, journalists and environmental groups obtained and publicized results showing that colonies exposed to high levels of the companies’ products experienced harmful effects, such as reduced colony health, while effects at lower, more typical levels were less clear. The companies argued their studies showed no significant harm under realistic conditions and criticized how the findings were presented. The episode highlighted questions about how regulators evaluate industry-funded studies and what exposure levels bees actually encounter in farm landscapes.

What Did Independent Studies Find About Bees?

Independent field studies found neonicotinoids can impair bees’ foraging, navigation, reproduction, and colony growth, with effects that are real but vary by species, dose, crop, and conditions. A large field study published in Science in 2017 by Ben Woodcock and colleagues at the U.K. Centre for Ecology and Hydrology examined honey bees, bumblebees, and solitary bees near fields of oilseed rape treated with clothianidin or thiamethoxam in the U.K., Hungary, and Germany. Neonicotinoid exposure reduced honey bee colony overwintering in the U.K. and Hungary but not in Germany, where colonies were healthier overall and had access to more diverse food. For wild bees, higher neonicotinoid residues in nests were associated with reduced reproduction. The study, partly funded by Bayer and Syngenta but run independently, suggested that effects depend on local conditions and are more consistent for wild bees.

A companion study in the same issue of Science by Nadejda Tsvetkov and colleagues in Canada found that honey bee colonies near corn fields were exposed to neonicotinoids for months, mostly through pollen from non-crop plants contaminated by seed-treatment dust or soil residues. Field-realistic exposure reduced worker bee survival and colony health, and the toxicity of neonicotinoids roughly doubled in the presence of a common fungicide.

A 2015 field study in Nature by Maj Rundlöf and colleagues in Sweden compared oilseed rape fields grown from clothianidin-coated seeds with untreated fields. Treated fields had lower wild bee density, solitary bees did not nest near them, and bumblebee colonies grew and reproduced less, while no significant effect was detected on honey bee colonies. Together, these studies indicate that neonicotinoids can harm bees under real farming conditions, with wild bees often more vulnerable than managed honey bees.

Are Neonicotinoids the Main Cause of Bee Decline?

Neonicotinoids are one of several pressures on bees, alongside the varroa mite, diseases, poor nutrition, and habitat loss; experts stress that bee decline results from these stressors acting together. Scientists generally agree that bee declines have multiple causes. Managed honey bee colonies face the parasitic Varroa mite and the viruses it spreads, poor nutrition from landscapes dominated by a few crops, loss of flowering habitat, and exposure to many pesticides, including fungicides and other insecticides. Wild bees, of which there are thousands of species in North America alone, face habitat loss, climate change, diseases spilling over from managed bees, and pesticides. Neonicotinoids interact with these stressors; for example, sublethal exposure may impair foraging, navigation, and immune responses, making bees more vulnerable to other threats. Honey bee colony numbers have been maintained by beekeepers replacing lost colonies, but beekeepers continue to report high annual losses.

Beyond Bees: Birds and Waterways

Concerns about neonicotinoids extend beyond pollinators. A 2019 study in Science by Margaret Eng and colleagues dosed migrating white-crowned sparrows with imidacloprid at levels comparable to eating a few treated seeds. Exposed birds rapidly reduced food intake, lost body mass and fat, and delayed their departure from migratory stopovers, which the authors said could affect survival and reproduction. Because neonicotinoids are water-soluble, they also wash into streams and wetlands, where they have been detected widely in agricultural regions and can harm aquatic insects such as mayflies and midges that are food for fish and birds. These broader ecological effects have become part of regulatory reviews.

The Bigger Picture on Bee Decline

A 2015 review in Science by Dave Goulson and colleagues concluded that bee declines are driven by combined stress from parasites, pesticides, and lack of flowers, and that these stressors interact; for example, poor nutrition can make bees more susceptible to pesticides and disease. The authors recommended reducing pesticide use, increasing flower-rich habitat in farmland and cities, and better management of parasites and diseases in managed bees. This combined-stressor view helps explain why studies sometimes find different effects in different places and why no single action will reverse bee declines.

How Do Neonicotinoid Rules Differ by Country?

The European Union banned the main neonicotinoids for outdoor use over bee concerns, while the United States has restricted some uses more slowly, reflecting different regulatory approaches. According to the European Commission, the EU restricted three neonicotinoids, clothianidin, imidacloprid, and thiamethoxam, in 2013 in bee-attractive crops. After the European Food Safety Authority confirmed in February 2018 that most uses posed risks to bees, the EU banned all outdoor uses of the three, allowing use only in permanent greenhouses. The Commission notes that several member states repeatedly granted emergency authorizations for restricted uses, which EU courts later limited. France banned neonicotinoids more broadly in 2018.

In the United States, the EPA’s registration review of neonicotinoids has been ongoing for years, including pollinator risk assessments, endangered species evaluations, and an occupational exposure assessment for seed treatments. Several states have acted on their own: New York enacted a law in 2023 phasing out neonicotinoid-treated corn, soybean, and wheat seeds, and other states restrict neonicotinoid use on lawns and ornamental plants or limit sales to licensed applicators.

Are Seed Treatments Needed?

Much of the neonicotinoid use on farms comes from seed coatings applied before planting, which protect seedlings from early-season soil pests. Critics argue that these coatings are used routinely on most corn and soybean acres even where pest pressure is low, adding exposure without clear benefit. Analyses by university researchers and the EPA have found that neonicotinoid seed treatments provide little or no yield benefit for soybeans in most situations. Supporters note that seed treatments can be valuable where pests are common and that farmers often have limited access to untreated seed. Making untreated seed widely available and using treatments only where needed are central to proposals for reducing neonicotinoid use.

What Gardeners and Homeowners Can Do

Check labels. Garden and lawn products containing imidacloprid, clothianidin, thiamethoxam, acetamiprid, or dinotefuran are neonicotinoids. Avoid applying them to plants that bees visit.

Ask nurseries. Some ornamental plants have been treated with neonicotinoids; many retailers now label or avoid treated plants.

Plant for pollinators. Diverse native flowers that bloom from spring through fall provide food for bees.

Use integrated pest management. Tolerate some damage, use targeted methods, and avoid spraying flowering plants.

Provide habitat. Leave some bare ground and plant stems for nesting solitary bees.

Neonicotinoid	Common uses	EU status
Imidacloprid	Seed treatments, lawns, ornamentals, pet flea products	Outdoor use banned 2018
Clothianidin	Corn and canola seed treatments	Outdoor use banned 2018
Thiamethoxam	Seed treatments, foliar sprays	Outdoor use banned 2018
Thiacloprid	Foliar sprays	Not renewed
Acetamiprid	Foliar sprays, home garden products	Approved with restrictions

The Debate Over Industry Data

Pesticide regulation relies heavily on studies conducted or funded by manufacturers, which must meet guidelines and are reviewed by regulators. Critics argue that this creates conflicts of interest and that study designs may not capture realistic exposures or sublethal effects on behavior and colony health. Supporters note that regulatory studies follow standardized protocols and are audited, and that independent research complements them. The neonicotinoid controversy encouraged regulators, particularly in Europe, to update bee risk assessment guidance to consider chronic effects, wild bees, and exposure through contaminated soil and wildflowers, beyond crops.

Alternatives for Farmers

Reducing neonicotinoid use on farms depends on alternatives. Integrated pest management, which monitors pest populations and uses treatments only when needed, can reduce routine prophylactic use. Crop rotation can break pest cycles. Other insecticides may be used when pests reach damaging levels, though some alternatives carry their own environmental risks. Planting flower strips and maintaining hedgerows supports beneficial insects that help control pests. Research in Europe after the 2018 ban found that some farmers adapted with modest yield effects, while others faced pest problems, particularly in sugar beets, prompting emergency authorizations that courts later restricted.

Key Facts at a Glance

Neonicotinoids are systemic insecticides widely used as seed coatings. A 2017 field study in three European countries found harm to honey bee colonies in the U.K. and Hungary but not Germany, and reduced wild bee reproduction with higher residues; a Canadian study found reduced honey bee health near corn. A 2015 Swedish study found reduced wild bee density and bumblebee colony growth near treated oilseed rape. A 2019 study found imidacloprid delayed songbird migration. The EU banned outdoor use of three neonicotinoids in 2018; EPA review continues, and New York enacted restrictions on treated seeds in 2023.

How Neonicotinoids Affect Individual Bees

At sublethal doses, neonicotinoids can affect bees in ways that are not immediately fatal but may weaken colonies over time. Laboratory and semi-field studies have reported impaired foraging efficiency, reduced ability to navigate back to the hive, effects on learning and memory, weakened immune responses, and reduced reproduction in bumblebee colonies and solitary bees. Because a honey bee colony functions as a superorganism with tens of thousands of workers, it can sometimes compensate for losses of individual foragers, which may explain why colony-level effects appear in some studies but not others. Bumblebee colonies and solitary bees, with far fewer individuals, have less capacity to absorb such losses.

Managed Versus Wild Bees

Public discussion often focuses on honey bees, which are managed by beekeepers and essential for pollinating crops such as almonds. But thousands of wild bee species, including bumblebees, mason bees, and mining bees, also pollinate crops and wild plants, and many have declined. Honey bee populations can be replenished by beekeepers splitting colonies and buying queens, masking losses, while wild bee populations depend on natural reproduction and habitat. Research suggests wild bees may be more vulnerable to neonicotinoids, partly because many species are solitary and some nest in soil that may contain residues. Protecting wild bees therefore requires attention to pesticides and habitat across landscapes, beyond just the area around apiaries.

Home Use and Pet Products

Neonicotinoids are used on farms and also in garden products, lawn grub treatments, tree injections, and veterinary flea and tick treatments for pets. Studies in Europe have detected imidacloprid and other insecticides from pet treatments in rivers, likely from washing pets or from runoff. Homeowners can reduce their contribution by using lawn and garden products only when necessary and following label directions, choosing non-neonicotinoid options where appropriate, and discussing flea control options with a veterinarian.

Common Myths

“Neonicotinoids are the sole cause of colony collapse.” Bee losses have multiple causes; neonicotinoids are one contributor.

“Honey bees are endangered.” Managed honey bee numbers are maintained by beekeepers despite high losses; many wild bee species are at greater risk.

“Organic farming never uses insecticides.” Organic farmers can use approved insecticides, some of which are toxic to bees, but synthetic neonicotinoids are prohibited.

“Banning neonicotinoids solves the problem.” Replacement insecticides can have their own effects; integrated approaches matter.

What Consumers Can Do

Consumers can support pollinators beyond their own gardens. Buying organic produce supports farming systems that prohibit synthetic neonicotinoids. Supporting local farmers who use integrated pest management and maintain habitat, contributing to pollinator habitat projects, and advocating for policies that reduce unnecessary pesticide use can all help. In cities, planting native flowers on balconies, in yards, and in public spaces provides food for bees. Avoiding pesticide use on lawns and accepting some “weeds” such as clover and dandelions also provides forage.

A Closer Look at the European Experience

Europe’s restrictions offer a natural experiment. After the 2013 partial restrictions and the 2018 outdoor ban, researchers and farm groups monitored effects on crops and pests. Oilseed rape growers in some countries reported increased damage from flea beetles, and some shifted to other insecticides such as pyrethroids, to which some pests had developed resistance. Sugar beet growers faced virus yellows disease spread by aphids, prompting several countries to grant emergency authorizations for neonicotinoid seed treatments; in 2023, the European Court of Justice ruled that such emergency authorizations could not be granted for seeds treated with banned neonicotinoids. Evidence on pollinator recovery after the bans is still accumulating, since bee populations respond to many factors and neonicotinoid residues can persist in soil for years.

Neonicotinoids in Water

Because neonicotinoids dissolve readily in water, they move from treated fields into streams, wetlands, and groundwater. Monitoring by the U.S. Geological Survey and other agencies has detected neonicotinoids frequently in streams in agricultural and urban areas. Aquatic insects, such as mayflies, are highly sensitive, and declines in these insects can ripple through food webs that support fish and birds. Some studies have also detected neonicotinoids in drinking water sources and treated tap water at low concentrations; health implications for people at these levels are not established, but the findings show how widely these chemicals spread in the environment.

Key Terms

Neonicotinoids: A class of systemic insecticides chemically related to nicotine.

Systemic insecticide: A pesticide absorbed and distributed throughout a plant, including pollen and nectar.

Seed treatment: Coating seeds with pesticides before planting.

Sublethal effects: Harmful effects that do not kill immediately, such as impaired foraging or reproduction.

Emergency authorization: A temporary exception allowing a restricted pesticide use.

The Bottom Line

Company-funded field studies revealed in 2017 and a series of independent studies show that neonicotinoids can harm bees under real farming conditions, with wild bees and bumblebees often more affected than managed honey bee colonies and effects varying with local conditions. Neonicotinoids are one of several stressors behind bee declines, alongside parasites, disease, poor nutrition, and habitat loss, and they can also affect birds and aquatic insects. The European Union banned outdoor use of three neonicotinoids in 2018, while the United States relies on an ongoing EPA review and state actions. Farmers, gardeners, and policymakers can help pollinators by reducing unnecessary insecticide use and expanding flowering habitat.

Further Reading

The European Commission and EFSA publish the scientific assessments behind the EU’s neonicotinoid decisions. The EPA’s pollinator protection pages track the U.S. registration review. University extension services and pollinator conservation organizations offer guidance on bee-friendly gardening and farming practices.

A Balanced View

Neonicotinoids were adopted partly because they replaced older insecticides that were more acutely toxic to people and wildlife, and they remain valuable tools against certain pests. The evidence now shows they also carry significant risks to pollinators and other wildlife, especially when used routinely as seed treatments regardless of pest pressure. A balanced approach recognizes both: using neonicotinoids only where needed, protecting flowering habitat, and evaluating alternatives carefully so that replacements do not create new problems. Policies in different countries reflect different weightings of these trade-offs, and continued research will refine them.

Questions to Ask Garden Centers

Were these plants treated with neonicotinoids or other systemic insecticides? Do you label treated plants? Which pest control products do you recommend that are safer for bees? Do you carry native plants that support local pollinators? Many garden centers have changed their practices in response to customer questions, and asking helps encourage further change.

Monitoring and Research Gaps

Scientists have identified gaps that make it hard to assess neonicotinoid risks fully. Data on wild bee populations are limited, making trends difficult to measure. Exposure varies widely by landscape, season, and crop, and bees encounter mixtures of pesticides rather than single chemicals. Long-term, landscape-scale studies are expensive and rare. Better monitoring of pollinator populations, pesticide use, and residues in the environment would help regulators evaluate whether policies are working and guide future decisions.

Pollinators and Food Security

About three-quarters of leading global food crops benefit to some degree from animal pollination, including many fruits, vegetables, nuts, and seeds that provide essential vitamins and minerals. While staple grains such as wheat, rice, and corn are wind-pollinated, pollinator declines could reduce yields and raise prices of nutritious foods. In the United States, crops such as almonds, apples, blueberries, cherries, and squash depend heavily on bees. Protecting pollinators is therefore both an environmental concern and important for agriculture and nutrition.

Signs of Pesticide Poisoning in Bees

Beekeepers sometimes observe acute pesticide poisoning: piles of dead or trembling bees at hive entrances, bees unable to fly, or sudden colony collapse after nearby spraying or planting with treated seed. Dust from seed planting equipment has caused acute bee kills in some regions, prompting changes in planting technology and practices. Beekeepers who suspect poisoning can report incidents to state agriculture departments and the EPA, and samples can be tested for pesticide residues. Sublethal effects are harder to detect, appearing as gradual colony decline rather than sudden deaths.

Creating Pollinator Habitat at Home

Even small spaces can help bees. Plant a mix of native flowers with different shapes and colors that bloom from early spring through late fall, since bees need food throughout the season. Include early bloomers such as willows and spring bulbs, and late bloomers such as asters and goldenrods. Group flowers in clumps so bees can forage efficiently. Leave some areas unmulched for ground-nesting bees and keep hollow plant stems over winter for cavity-nesting species. Provide a shallow water source with stones for landing. Avoid using insecticides on flowering plants, and if pest control is needed, choose targeted methods applied in the evening when bees are less active.

Local native plant societies and extension services can recommend species suited to your region.

What Beekeepers Report

U.S. beekeepers have reported high annual colony losses in surveys conducted since the mid-2000s, often losing 30 to 50 percent of colonies in a year, well above the level they consider acceptable. Beekeepers cite Varroa mites, poor queens, weather, starvation, and pesticide exposure among causes. Many have adapted by splitting colonies, buying replacement queens, feeding supplements, and moving hives away from heavily treated farmland. These efforts keep colony numbers relatively stable but raise costs for beekeepers and, ultimately, for farmers who rent bees for pollination.

Urban Landscapes and Bees

Cities can be surprisingly good habitat for bees, with diverse flowers in gardens, parks, and green roofs. However, ornamental plants sold in garden centers and lawn treatments can expose urban bees to neonicotinoids. Several cities and states have restricted neonicotinoid use on public land or by homeowners, and some retailers have stopped selling neonicotinoid-treated plants. Municipal pollinator programs that plant native flowers along roads and in parks expand food sources for bees in urban areas.

Research on urban bee communities has found surprisingly high diversity in well-planted city gardens, showing that thoughtful planting choices by individual residents can make a measurable difference for local pollinators, especially when neighbors coordinate plantings across a block or community.

Schools, churches, and businesses with landscaped grounds can also contribute by replacing some lawn with flowering native plants, adopting pesticide policies that protect pollinators, and using signage to explain these choices, which helps build community understanding of why a less manicured landscape can benefit bees and other wildlife, including butterflies, moths, and the birds that feed on insects.

Frequently Asked Questions

Do neonicotinoids kill bees?

Neonicotinoids can harm bees, but they are one of several pressures rather than the single cause of bee decline. At high doses they kill bees directly, and at lower, field-realistic doses independent studies show they can impair foraging, navigation, reproduction, and colony health. Their impact is real but interacts with other stressors like the varroa mite, disease, poor nutrition, and habitat loss.

Are neonicotinoids the main reason bees are declining?

No single factor explains bee decline. Scientists point to a combination of the varroa mite and the viruses it spreads, diseases, loss of flower-rich habitat, poor nutrition, climate stress, and pesticides including neonicotinoids. Neonicotinoids are an important and controllable piece of the puzzle, but protecting bees requires addressing all these stressors together rather than focusing on pesticides alone.

Why did company studies and independent studies disagree?

Industry-funded studies often found little harm to bees at realistic field doses, while independent field research more often detected effects on foraging, reproduction, and colony growth. Critics noted that company studies sometimes had design limitations and that funding can influence how research is framed. This pattern, seen in other fields too, is why independent replication and disclosure of funding are so important.

Are neonicotinoids banned?

It depends on the country. The European Union banned the three main neonicotinoids for outdoor agricultural use in 2018 over concerns about bees, allowing only limited exceptions. The United States has moved more slowly, restricting certain uses and reviewing others rather than imposing a broad ban. This reflects the EU’s more precautionary approach compared with U.S. pesticide regulation.

How can I help protect bees?

You can plant diverse, pesticide-free flowers that bloom across the seasons, avoid using neonicotinoid and other insecticides in your garden, and leave some areas a little wild for nesting. Buying organic or pollinator-friendly products supports farming that reduces pesticide use. Supporting habitat conservation and policies that protect pollinators also helps address the multiple pressures bees face beyond any single garden.

References

1. Woodcock BA, Bullock JM, Shore RF, et al. Country-specific effects of neonicotinoid pesticides on honey bees and wild bees. Science. 2017;356(6345):1393–1395. PMID 28663502
2. Tsvetkov N, Samson-Robert O, Sood K, et al. Chronic exposure to neonicotinoids reduces honey bee health near corn crops. Science. 2017;356(6345):1395–1397. PMID 28663503
3. Rundlöf M, Andersson GK, Bommarco R, et al. Seed coating with a neonicotinoid insecticide negatively affects wild bees. Nature. 2015;521(7550):77–80. PMID 25901681
4. European Commission. Neonicotinoids. food.ec.europa.eu
5. European Food Safety Authority. Neonicotinoids: risks to bees confirmed. February 28, 2018. efsa.europa.eu
6. U.S. Environmental Protection Agency. Schedule for Review of Neonicotinoid Pesticides. epa.gov
7. Eng ML, Stutchbury BJM, Morrissey CA. A neonicotinoid insecticide reduces fueling and delays migration in songbirds. Science. 2019;365(6458):1177–1180. PMID 31515394
8. Goulson D, Nicholls E, Botías C, Rotheray EL. Bee declines driven by combined stress from parasites, pesticides, and lack of flowers. Science. 2015;347(6229):1255957. PMID 25721506

Last updated: October 6, 2026