Neonicotinoids & Pesticide Policy

The Compounds

Neonicotinoids are a class of systemic insecticides that act on the nicotinic acetylcholine receptors of the insect nervous system. "Systemic" means the compound is absorbed into the plant's vascular tissue and distributed throughout its tissues - including the pollen and nectar that pollinators collect. A treated plant's flowers contain measurable neonicotinoid residues for the duration of the bloom period.

Three compounds dominate the market and the controversy:

• Imidacloprid (Bayer, 1991) - The first commercially successful neonicotinoid. The most widely used insecticide in the world by sales volume for most of the 2000s.
• Clothianidin (Bayer, 2003) - A metabolite of thiamethoxam and a standalone product. Higher acute toxicity to bees than imidacloprid.
• Thiamethoxam (Syngenta, 2000) - Partially metabolized to clothianidin in plants, effectively delivering two neonicotinoid compounds from a single application.

These three compounds account for approximately 25% of the global insecticide market - roughly $4.5 billion in annual sales. In the United States, neonicotinoids are applied to an estimated 150 million acres of cropland annually, primarily as seed treatments on corn, soybeans, cotton, and canola. Seed treatment is the dominant application method: the seeds are coated with the insecticide before planting, and the chemical is taken up by the growing plant.

The Evidence of Harm

The scientific literature on neonicotinoid effects on pollinators is extensive - exceeding 1,500 peer-reviewed papers as of 2025. The research documents harm at multiple levels:

Acute Toxicity

Neonicotinoids are acutely toxic to honey bees at low doses. The oral LD50 (dose that kills 50% of test subjects) for imidacloprid in honey bees is approximately 3.7 nanograms per bee - roughly one-billionth of the bee's body weight. For context: the corresponding figure for DDT was approximately 27,000 nanograms per bee. Neonicotinoids are roughly 7,000 times more toxic to bees per unit mass than DDT.

Sublethal Effects

The acute toxicity, while striking, is arguably less important than the sublethal effects - impacts that don't kill the bee outright but impair her function. Research has documented sublethal effects at field-realistic concentrations (1-10 parts per billion in nectar):

• Learning and memory impairment. Bees exposed to sublethal doses show reduced ability to form associative memories in the proboscis extension reflex assay - the standard test for bee cognitive function. Exposed bees require more trials to learn and form weaker, shorter-lasting memories.
• Navigation disruption. Foragers exposed to sublethal doses of imidacloprid and thiamethoxam show increased homing failure rates - they leave the hive to forage and fail to return. GPS tracking studies have documented significant increases in non-return rates at doses below 10 ppb.
• Foraging efficiency. Exposed foragers make fewer foraging trips per day, visit fewer flowers per trip, and bring back less nectar and pollen.
• Immune suppression. Neonicotinoid exposure compromises the bee immune system, increasing susceptibility to Nosema, deformed wing virus, and other pathogens. The interaction between pesticide exposure and pathogen pressure is synergistic - the combined effect exceeds the sum of individual effects.
• Queen reproductive impairment. Queens exposed during development show reduced ovarian mass, lower sperm viability in stored sperm, and shorter productive lifespans.
• Colony-level impacts. Field studies on whole colonies have shown reduced colony growth, lower honey production, and higher winter mortality in colonies placed in neonicotinoid-treated crop landscapes compared to untreated controls.

Environmental Persistence

Neonicotinoids persist in soil far longer than most insecticides. Soil half-lives range from 200 days (thiamethoxam) to over 1,000 days (clothianidin) depending on soil conditions. This means residues accumulate year over year in fields with repeated annual applications - a phenomenon documented in long-term soil monitoring studies. The compounds are water-soluble and leach into groundwater and surface water, where they have been detected at concentrations sufficient to affect aquatic invertebrates.

Dust-Off Exposure

When neonicotinoid-coated seeds are planted by pneumatic planters (the standard method for corn and soybeans), the abrasion of seeds against each other and against the planter mechanism generates dust containing high concentrations of the insecticide. This dust is expelled from the planter's exhaust and can drift to adjacent flowering crops, hedgerows, and wildflower areas. Documented bee kill events in Europe and North America have been attributed to planting-time dust drift.

The Regulatory Landscape

European Union

The EU imposed temporary restrictions on three neonicotinoids (imidacloprid, clothianidin, thiamethoxam) in 2013, limiting their use on bee-attractive crops. In 2018, the European Commission voted to make the outdoor use ban permanent, based on a comprehensive risk assessment by the European Food Safety Authority (EFSA) that concluded the compounds posed unacceptable risks to wild and managed bees. Greenhouse use remains permitted. France subsequently extended the ban to include two additional neonicotinoids (thiacloprid and acetamiprid).

United States

The EPA completed interim registration review decisions for imidacloprid (2020), clothianidin (2020), and thiamethoxam (2020). The assessments acknowledged risks to pollinators but imposed limited new restrictions - primarily label language changes and application timing restrictions rather than use prohibitions. The decisions were challenged in federal court by environmental groups. As of 2026, the EPA's final registration review decisions remain pending.

State-level action has been more aggressive. Several states have restricted consumer (non-agricultural) neonicotinoid sales or enacted pollinator protection plans. Maryland banned consumer neonicotinoid sales in 2018. Connecticut followed in 2023. New Jersey, Vermont, and New York have enacted various restrictions. However, agricultural use - which accounts for the overwhelming majority of neonicotinoid application - remains largely unrestricted at the state level.

The Regulatory Gap

The core tension: EPA risk assessments document pollinator harm at field-realistic exposure levels. The regulatory response has not matched the risk assessment findings. The EU used substantially the same body of scientific evidence and reached a different regulatory conclusion. The discrepancy between US and EU responses to the same science is one of the most debated topics in pollinator conservation.

The Economic Dimension

The argument for neonicotinoid use is economic: they protect crop yields from insect damage, and their systemic mode of action makes them convenient (seed treatments require no in-season application). The crop protection value is real. Estimates of neonicotinoid-attributable yield protection in US corn and soybeans range from $2 billion to $4 billion annually.

The counterargument is also economic: pollination services in the US are valued at $20-30 billion annually. Managed colony losses cost the beekeeping industry an estimated $2 billion per year in replacement costs. Native pollinator declines threaten pollination services for crops and wild plants that neonicotinoids are not protecting. If neonicotinoid use contributes even modestly to pollinator declines (and the evidence suggests it does), the net economic calculation may favor restriction.

The economic framing has limits. It doesn't capture the ecological value of pollinators in wild ecosystems, the cultural and food security implications of pollinator decline, or the option value of maintaining pollinator populations for future agricultural needs. But even within a narrow cost-benefit framework, the case for continued unrestricted use is weaker than the agrochemical industry's advocacy suggests.

Where The Apiary Project Stands

The Apiary Project's position is that the scientific evidence is sufficient to justify precautionary restrictions on outdoor use of imidacloprid, clothianidin, and thiamethoxam on bee-attractive crops, consistent with the EU's 2018 decision. This position is based on:

1. The documented sublethal effects at field-realistic concentrations.
2. The environmental persistence and accumulation potential.
3. The synergistic interactions with pathogens and other stressors.
4. The availability of alternative pest management approaches for major crops.
5. The economic value of the pollination services at risk.

We recognize that neonicotinoids are not the sole cause of pollinator decline. Varroa mites, habitat loss, climate change, and management practices all contribute. But the fact that multiple factors are involved does not mean any individual factor should be ignored when the evidence of harm is clear.

We also recognize that a transition away from neonicotinoids requires viable alternatives for farmers. Integrated pest management, biological controls, and alternative chemistries exist but require investment, education, and policy support to scale. Any restriction should be accompanied by support for farmers navigating the transition.