DONATE
DONATE

Insecticides (Neonics) Overview

Insecticides are “chemicals used to control insects by killing them or preventing them from engaging in undesirable or destructive behaviors.”[1] Most insecticides are neurotoxins that disrupt an insect’s nervous system resulting in death.[2,3]

 

  1. U.S. EPA (2024) Insecticides Overview. https://www.epa.gov/caddis/insecticides
  2. Scharf, M. E. (2008). Neurological effects of insecticides and the insect nervous system. Encyclopedia of entomology. Springer, NY, 2596-2607. [“…the vast majority of chemical insecticides in use today act upon the insect central nervous system.”] 
  3. Sass, J. B., et al., (2024). Neonicotinoid pesticides: evidence of developmental neurotoxicity from regulatory rodent studies. Frontiers in Toxicology, 6, 1438890, p. 2. [“Most major classes of insecticides act by disrupting the nervous system…”]

Neonicotinoids (commonly called neonics) are a class of insecticides developed in the 1990’s that have become the most widely used insecticides in the world. They act systemically, becoming incorporated into plant tissue, thereby protecting the whole plant.

Neonicotinoids are neurotoxins (affecting the nervous system) that cause insect paralysis and death. They are chemically similar to nicotine, hence the name which means “new nicotine-like compound.” Since they are systemic, they are present throughout the plant, including the nectar and pollen of the treated crops. Most neonicotinoids are applied as seed treatments (aka seed dressings). Minute quantities in plant tissue (5 or 10 parts per billion) are effective.[1-3]

 

  1. Goulson, D. (2013). An overview of the environmental risks posed by neonicotinoid insecticides. The Journal of Applied Ecology, 50(4), 977–987, pp. 977-979. https://doi.org/10.1111/1365-2664.12111.
  2. European Commission (n.d.) Some facts about neonicotinoids. https://food.ec.europa.eu/plants/pesticides/approval-active-substances-safeners-and-synergists/renewal-approval/neonicotinoids_en
  3. Grout, T. A., et al., (2020). Neonicotinoid Insecticides in New York State. Cornell University, pp. 48-68. https://waterfrontonline.blog/wp-content/uploads/2023/10/cornell2020studybees.pdf

Neonics are the most widely used insecticides in the world, and almost certainly the most widely used in the U.S. They are by far the most toxic to insects, as well as the most damaging to non-target animals and the most pervasive and persistent in the wider environment. They are central to feed crop production, with almost all corn and most soybeans grown from seeds that have been treated with neonics.[1]

 

  1. See the following Q & A’s on this post along with the subsequent post on neonics on feed crops.

So called “conventional” insecticides are usually sprayed on soil or on foliage. Neonics are predominantly applied to seeds before planting.[1] A small amount of neonics, typically less than 10%, gets absorbed into the plant and becomes systemic throughout tissues and foliage. About 90% of the active ingredients is dispersed into the environment.[2,3]

Although the volume by weight is small compared to conventional insecticides, the toxicity and persistence are unusually high.[4,5] Whereas conventional insecticides have half-lives under 30 days, neonic residues may remain in the soil for several years.[6,7]

The use of neonics has, according to some researchers, moved insecticide treatments from a more conventional “as-needed” basis to a full-on, yearly, broad-spectrum approach.[8,9]

 

  1. Douglas, M. R., & Tooker, J. F. (2015). Large-Scale Deployment of Seed Treatments Has Driven Rapid Increase in Use of Neonicotinoid Insecticides and Preemptive Pest Management in U.S. Field Crops. Environmental Science & Technology, 49(8), 5088–5097, p. 5092. [“From 2000 to 2012, virtually all neonicotinoids applied to maize, soybeans, and wheat were applied as seed treatments.”]
  2. Wood, T. J., & Goulson, D. (2017). The environmental risks of neonicotinoid pesticides: a review of the evidence post 2013. Environmental Science and Pollution Research International, 24(21), 17285–17325, p. 17285. [“However, only approximately 5% of the neonicotinoid active ingredient is taken up by crop plants and most instead disperses into the wider environment.”]
  3. Tooker, J. F. et al., (2017). Neonicotinoid Seed Treatments: Limitations and Compatibility with Integrated Pest Management. Agricultural & Environmental Letters, 2(1), 1–5, p. 4. [“The amount of neonicotinoid applied to seeds that actually gets absorbed by plants is typically about 1 to 10%; the rest remains in soil where it is vulnerable to leaching.”] 
  4. DiBartolomeis, M., et al., (2019). An assessment of acute insecticide toxicity loading (AITL) of chemical pesticides used on agricultural land in the United States. PloS one, 14(8), e0220029. [“Neonicotinoids are primarily responsible for this increase (in acute toxicity), representing between 61 to nearly 99 percent of the total toxicity loading in 2014.” at p. 1. “…neonicotinoid residues from seed treatments may be found in the soil for months or even years after planting.” at p. 5]
  5. Douglas, M. R., et al., (2020). County-level analysis reveals a rapidly shifting landscape of insecticide hazard to honey bees (Apis mellifera) on US farmland. Scientific Reports, 10(1), 797, p. 6. [“Neonicotinoids accounted for the overwhelming majority of oral toxic load by 2012.” See also, Figure 5c for comparisons of “overall toxic load” showing neonics contribute the great majority in all agricultural regions of the U.S.]
  6. Bonmatin, J. M. et al., (2015). Environmental fate and exposure; neonicotinoids and fipronil. Environmental Science and Pollution Research International, 22(1), 35–67, p. 35. […the half-lives of neonicotinoids in soils can exceed 1,000 days, so they can accumulate when used repeatedly. Similarly, they can persist in woody plants for periods exceeding 1 year.”]
  7. Ospina, M., et al., (2019). Exposure to neonicotinoid insecticides in the US general population: Data from the 2015–2016 national health and nutrition examination survey. Environmental research, 176, 108555, p.2. [“…half-lives varied from a few days to several years…”]
  8. Goulson, D. (2013). An overview of the environmental risks posed by neonicotinoid insecticides. The Journal of Applied Ecology, 50(4), 977–987, p. 978. [“The widespread adoption of neonicotinoids as seed dressings has led to a move away from integrated pest management (IPM), a philosophy of pest management predicated on minimizing use of chemical pesticides via monitoring of pest populations, making maximum use of biological and cultural controls, applying chemical pesticides only when needed and avoiding broad-spectrum, persistent compounds.”]
  9. Tooker, J. F. et al. (2017).

According to USGS and EPA scientists, neonics are the most widely used insecticides in the world.[1,2] However, it is likely that researchers refrain from definitively saying that neonics are the most widely used insecticides in the U.S. because no federal agency monitors their use and because the actual volume of seed treatments is difficult to ascertain.[3]

Neonics are undoubtedly heavily applied in the U.S. which is likely the world’s top user.[4-6] The great majority of neonics are applied as seed treatments.[7] The 3 most commonly used neonics are thiamethoxam, imidacloprid and clothianidin.[8,9]

In 2018, the European Union almost completely banned the use of these 3 neonics.[10]

 

  1. Hladik, M. L., et al., (2018). Year-round presence of neonicotinoid insecticides in tributaries to the Great Lakes, USA. Environmental Pollution (1987), 235, 1022–1029, p. 1022.
  2. Thompson, D. A., et al., (2023). Prevalence of neonicotinoid insecticides in paired private-well tap water and human urine samples in a region of intense agriculture overlying vulnerable aquifers in eastern Iowa. Chemosphere (Oxford), 319, 137904, p. 2. 
  3. Douglas, Krupke & Tooker (February 9, 2024) Comments re: Requirements Applicable to Treated Seed (EPA–HQ–OPP–2023–0420), p. 4. [These 3 experienced researchers comment, “Given their significance in the landscape, it is remarkable that EPA notes in the federal register that it ‘does not have current and reliable information quantifying the total pounds of active ingredient used to treat seed or the location and the number of acres planted with treated seed.’ This also describes the situation of academic scientists and agricultural extension personnel, who lack high-quality data on seed treatment usage since 2014.”]
  4. Hitaj, C., et al., (2020). Sowing Uncertainty: What We Do and Don’t Know about the Planting of Pesticide-Treated Seed. Bioscience, 70(5), 390–403, p. 391. https://doi.org/10.1093/biosci/biaa019 [“Over the 2012–2014 period, approximately 90% of corn, 76% of soybean, 62% of cotton, and 56% of winter wheat acres in the United States were planted with treated seed (Kynetec 2019).” This is well over half of all cropland.]
  5. John F. Tooker (2022) Farmers are overusing insecticide on seeds, with mounting harmful effects on nature, Louisiana Illuminator. https://lailluminator.com/2022/02/22/farmers-are-overusing-insecticide-on-seeds-with-mounting-harmful-effects-on-nature/ [According to this researcher, “By my estimate, based on acres planted in 2021, neonicotinoids will be deployed across at least 150 million acres of cropland – an area about the size of Texas.” 150 million acres is approximately 45% of all planted cropland.]
  6. Krupke, C. H., & Tooker, J. F. (2020). Beyond the Headlines: The Influence of Insurance Pest Management on an Unseen, Silent Entomological Majority. Frontiers in Sustainable Food Systems, https://doi.org/10.3389/fsufs.2020.595855 [“The U.S. is the top user of neonicotinoids, by a wide margin…”]
  7. Douglas, M. R., & Tooker, J. F. (2015). Large-Scale Deployment of Seed Treatments Has Driven Rapid Increase in Use of Neonicotinoid Insecticides and Preemptive Pest Management in U.S. Field Crops. Environmental Science & Technology, 49(8), 5088–5097, p. 5092. [“From 2000 to 2012, virtually all neonicotinoids applied to maize, soybeans, and wheat were applied as seed treatments.”]
  8. Bass, C., et al., (2015). The global status of insect resistance to neonicotinoid insecticides. Pesticide biochemistry and physiology, 121, 78-87, p. 78. [Globally, “thiamethoxam, imidacloprid and clothianidin (account) for almost 85% of the total neonicotinoid sales in crop protection in 2012.”]
  9. Hladik, M. L. et al., (2014). Widespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region. Environmental Pollution, 193, 189-196, p. 189. [“ The most commonly-used neonicotinoids on corn and soybeans include clothianidin, imidacloprid, and thiamethoxam.”] 
  10. European Commission on Food Safety (n.d.) Some facts about neonicotinoids. https://food.ec.europa.eu/plants/pesticides/approval-active-substances/renewal-approval/neonicotinoids_en. [“the conditions of approval of the active substances imidacloprid, clothianidin and thiamethoxam have been published in the Official Journal of the European Union on 30 May 2018. As a result, all outdoor uses of the three substances are banned and only the use in permanent greenhouses remains possible.”]

The great majority of neonics are applied to corn and soybeans, the primary feed crops.[1]

 

  1. See, Neonics Use on Feed Crops

As early as 2014, USGS scientists were warning that neonics “are both mobile and persistent in the environment” and that they were found “more frequently and in higher concentrations” than historically-used pesticides.[1] It is estimated that less than 10% of the insecticide in treated seeds is taken up by the plant; the rest is lost into soil and water and can persist in soil for years.[2,3]

A report by USGS and EPA scientists found that the 3 most common neonics (clothianidin, thiamethoxam, and imidacloprid) were “found to be prevalent throughout the year in sampled tributaries to the Great Lakes, the largest freshwater ecosystem in the world.”[4] A nationwide USGS study covering 24 states detected at least one neonic formulation in 63% of sampled streams.[5]

Widespread neonic contamination of drinking water in agricultural areas has been documented.[6,7] A CDC report estimated that in 2015 about half of Americans had neonics in their urine.[8] Neonics are regularly detected at low levels in many foods, especially fruits and vegetables.[9]

 

  1. Hladik, M. L. et al., (2014). Widespread occurrence of neonicotinoid insecticides in streams in a high corn and soybean producing region, USA. Environmental Pollution (1987), 193, 189–196, p. 195.
  2. Tooker, J. F. et al., (2017). Neonicotinoid Seed Treatments: Limitations and Compatibility with Integrated Pest Management. Agricultural & Environmental Letters, 2(1), 1–5, p. 4. [“The amount of neonicotinoid applied to seeds that actually gets absorbed by plants is typically about 1 to 10%; the rest remains in soil where it is vulnerable to leaching.”]
  3. Bonmatin, J.M., et al., (2015). Environmental fate and exposure; neonicotinoids and fipronil. Environmental Science and Pollution Research International, 22(1), 35–67, p. 35. [“…the half-lives of neonicotinoids in soils can exceed 1,000 days, so they can accumulate when used repeatedly.”]
  4. Hladik, M. L., et al., (2018). Year-round presence of neonicotinoid insecticides in tributaries to the Great Lakes, USA. Environmental pollution, 235, 1022-1029, p. 1028.
  5.  Hladik, M. L., & Kolpin, D. W. (2015). First national-scale reconnaissance of neonicotinoid insecticides in streams across the USA. Environmental Chemistry, 13(1), 12-20. [Across all study areas, at least one neonicotinoid was detected in 63% of the 48 streams sampled.]
  6. Thompson, D. A. et al., (2023). Prevalence of neonicotinoid insecticides in paired private-well tap water and human urine samples in a region of intense agriculture overlying vulnerable aquifers in eastern Iowa. Chemosphere (Oxford), 319, 137904, Abstract. [“Human exposure was ubiquitous in urine samples.”]
  7. Klarich, K. L. et al., (2017). Occurrence of Neonicotinoid Insecticides in Finished Drinking Water and Fate during Drinking Water Treatment. Environmental Science & Technology Letters, 4(5), 168–173. 
  8. Ospina, M., et al., (2019). Exposure to neonicotinoid insecticides in the US general population: Data from the 2015–2016 national health and nutrition examination survey. Environmental research, 176, 108555, p. 1. [“The weighted frequency of having detectable concentrations of at least one of the six biomarkers examined was 49.1%.”]
  9. Craddock, H. A., et al., (2019). Trends in neonicotinoid pesticide residues in food and water in the United States, 1999–2015. Environmental Health, 18, 1-16, p. 4. [Neonics detected on more than 20% of samples: apple commodities, cherries, pears, strawberries, cauliflower, celery, cherries, cilantro, grapes, greens-collard, greens-kale, lettuce, potatoes, and spinach.]

The damaging effects of neonics to non-target animals are persistent, widespread, and well documented.[1-3]

Neonics are understood to be damaging to pollinators,[4,5] birds,[6,7] fish,[8] mammals,[9] and of course a wide range of non-target insects.[10,11]

 

  1. Bonmatin, J.M. et al., (2015). Environmental fate and exposure; neonicotinoids and fipronil. Environmental Science and Pollution Research International, 22(1), 35–67, p. 35. [“…measurements taken from water have been found to exceed ecotoxicological limits on a regular basis around the globe. The presence of these compounds in the environment suggests that all kinds of nontarget organisms will be exposed to them.”] 
  2. Goulson, D. (2013). An overview of the environmental risks posed by neonicotinoid insecticides. The Journal of Applied Ecology, 50(4), 977–987.  [“…UK indices for bees, butterflies, moths, carabid beetles and birds… all show significant overall declines in recent years…. The evidence presented here suggests that the annually increasing use of neonicotinoids may be playing a role in driving these declines.” (at pp. 984-985)]
  3. Mamy, L., et al., (2023). Impacts of neonicotinoids on biodiversity: a critical review. Environmental Science and Pollution Research, 1-36. [“…this review showed that these substances have particularly high direct and indirect impacts on terrestrial invertebrates and vertebrates, and on aquatic invertebrates.”]
  4. Rundlöf, M. et al., (2015). Seed coating with a neonicotinoid insecticide negatively affects wild bees. Nature (London), 521(7550), 77–80. 
  5. Sánchez-Bayo, F., et al., (2016). Are bee diseases linked to pesticides? A brief review. Environment international, 89, 7-11, p. 10. [“Therefore, neonicotinoids and interacting pesticides (e.g. EIFs) are important stress factors underpinning colony health decline and eventual collapse, significantly contributing to the spread and abundance of pathogens and parasites, which are the proximate mortality factors.”]
  6. Molenaar, E., et al., (2024). Neonicotinoids Impact All Aspects of Bird Life: A Meta‐Analysis. Ecology Letters, 27(10), e14534, Abstract. [“…we use a meta-analytical approach synthesising 1612 effect sizes from 49 studies and show that neonicotinoids consistently harm bird health, behaviour, reproduction, and survival.”] 
  7. Li, Y. et al., (2020). Neonicotinoids and decline in bird biodiversity in the United States. Nature Sustainability, 3(12), 1027–1035.
  8. Yamamuro, M. et al., (2019). Neonicotinoids disrupt aquatic food webs and decrease fishery yields. Science (American Association for the Advancement of Science), 366(6465), 620–623.
  9. Goulson, D. (2013), p. 983. [“Although vertebrates are less susceptible than arthropods, consumption of small numbers of dressed seeds offers a route to direct mortality in birds and mammals.” Sublethal effects in mammals “include reduced reproduction, premature deliveries and deformities in foetuses.”]
  10. Sánchez-Bayo, F. & Wyckhuys, K. A. G. (2019). Worldwide decline of the entomofauna: A review of its drivers. Biological Conservation, 232, 8–27, p. 10. [For example, for butterflies and moths “…the steepest declines occurred in areas with high proportions of farmland treated with neonicotinoid insecticides…”]
  11. For more information on the impacts of neonics on biodiversity, see Insecticide Harm to Biodiversity

Fertilizers & Pesticide