Pesticide toxicity to bees
Pesticides vary in their effects on bees. Contact pesticides are usually sprayed on plants and can kill bees when they crawl over sprayed surfaces of plants or other areas around it. Systemic pesticides, on the other hand, are usually incorporated into the soil or onto seeds and move up into the stem, leaves, nectar, and pollen of plants.
Of contact pesticides, dust and wettable powder pesticides tend to be more hazardous to bees than solutions or emulsifiable concentrates. When a bee comes in contact with pesticides while foraging, the bee may die immediately without returning to the hive. In this case, the queen bee, brood, and nurse bees are not contaminated and the colony survives. Alternatively, the bee may come into contact with an insecticide and transport it back to the colony in contaminated pollen or nectar or on its body, potentially causing widespread colony death.
Actual damage to bee populations is a function of toxicity and exposure of the compound, in combination with the mode of application. A systemic pesticide, which is incorporated into the soil or coated on seeds, may kill soil-dwelling insects, such as grubs or mole crickets as well as other insects, including bees, that are exposed to the leaves, fruits, pollen, and nectar of the treated plants.
Pesticides, especially neonicotinoids, have been investigated in relation to Colony Collapse Disorder. Potentially toxic effects studied in the laboratory have often been followed by field studies that fail to show effects on actual bee populations. Despite gaps in the scientific evidence, regulators have restricted the use of neonicotinoids in Europe and elsewhere largely on the basis of concerns for bee health.
Insecticide toxicity is generally measured using acute contact toxicity values LD50 – the exposure level that causes 50% of the population exposed to die. Toxicity thresholds are generally set at
- highly toxic (acute LD50 < 2μg/bee)
- moderately toxic (acute LD50 2 - 10.99μg/bee)
- slightly toxic (acute LD50 11 - 100μg/bee)
- nontoxic (acute LD50 > 100μg/bee) to adult bees.
The acute toxicity of pesticides on bees, which could be by contact or ingestion, is usually quantified by LD50. Acute toxicity of pesticides causes a range of effects on bees, which can include agitation, vomiting, wing paralysis, arching of the abdomen similar to sting reflex, and uncoordinated movement. Acute toxicity may depend on the mode of exposure, for instance, many pesticides cause toxic effects by contact while neonicotinoids are more toxic when consumed orally. The acute toxicity, although more lethal, is less common than sub-lethal toxicity or cumulative effects.
Sublethal and chronic effects
Field exposure to pesticides, especially with relation to neonicotinoids, may lead to multiple physiological and/or behavioral sublethal effects in exposed bees. Sublethal effects to honey bees can include behavioral disruptions such as disorientation, thermoregulation, reduced foraging, decreased flight and locomotion abilities, impaired memory and learning, phototaxis (response to light), and altered communication behaviors. Additional sub-lethal effects may include compromised immunity of bees and delayed development.
Colony collapse disorder
Colony collapse disorder (CCD) is a syndrome that is characterized by the sudden loss of adult bees from the hive. Many possible explanations for it have been proposed, but no one primary cause has been found. The US Department of Agriculture indicated in a 2010 report to Congress that a combination of factors could be causing colony collapse disorder, including pesticides, pathogens, and parasites. Although pesticides were suspected to be part of the problem, a survey of healthy and CCD-affected colonies revealed similar levels of pesticides in wax and pollen.
Bee kill rate per hive
The kill rate of bees in a single bee hive can be classified as:
- < 100 bees per day - normal die off rate
- 200-400 bees per day - low kill
- 500-900 bees per day - moderate kill
- 1000+ bees per day - High Kill
Pesticides come in different formulations:
- Dusts (D)
- Wettable powders (WP)
- Soluble powders (SP)
- Emulsifiable concentrates (EC)
- Solutions (LS)
- Granulars (G)
All substances listed are insecticides, except for 2,4-D, which is an herbicide. Some substances are arachnicides too.
|Common name (ISO)||Examples of Brand names||Pesticide Class||length of residual toxicity||Comments||Bee toxicity|
|Aldicarb||Temik||Carbamate||apply 4 weeks before bloom||Relatively nontoxic|
(b) Sevin XLR
|Carbamate||High risk to bees
foraging even 10 hours after spraying; 3 – 7 days (b) 8 hours @ 1.5 lb/acre (1681 g/Ha) or less.
|Bees poisoned with carbaryl can take 2–3 days to die, appearing inactive as if cold. Sevin should never be sprayed on flowering crops, especially if bees are active and the crop requires pollination. Less toxic formulations exist.||Highly toxic|
|Carbofuran||Furadan||Carbamate||7 – 14 days||U.S. Environmental Protection Agency ban on use on crops grown for human consumption (2009) carbofuran (banned in granular form)||Highly toxic|
|Methomyl||Lannate, Nudrin||Carbamate||2 hours||Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.||Highly toxic|
|Pirimicarb||Pirimor, Aphox||Carbamate||Relatively nontoxic|
|Propoxur||Baygon||Carbamate||Propoxur is highly toxic to honey bees. The LD50 for bees is greater than one ug/honey bee.||Highly toxic|
|Acephate||Orthene||Organophosphate||3 days||Acephate is a broad-spectrum insecticide and is highly toxic to bees and other beneficial insects.||Moderately toxic|
|Azinphos-methyl||Guthion, Methyl-Guthion||Organophosphate||2.5 days||Banned in EU since 2006.||Highly toxic|
|Chlorpyrifos||Dursban, Lorsban||Organophosphate||Banned in US for home and garden use. Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.||Highly toxic|
|Coumaphos||Checkmite||Organophosphate||This is an insecticide that is used inside the beehive to combat varroa mites and small hive beetles, which are parasites of the honey bee. Overdoses can lead to bee poisoning.||Relatively nontoxic|
|Demeton||Systox||Organophosphate||<2 hours||Highly toxic|
|Demeton-S-methyl||Meta-systox||Organophosphate||Banned worldwide for toxicity to humans||Moderately toxic|
|Diazinon||Spectracide||Organophosphate||Sale of diazinon for residential use was discontinued in the U.S. in 2004. Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.||Highly toxic|
|Dicrotophos||Bidrin||Organophosphate||Dicrotophos toxicity duration is about one week.||highly toxic|
|Dichlorvos||DDVP, Vapona||Organophosphate||Highly toxic|
|Dimethoate||Cygon, De-Fend||Organophosphate||3 days||Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.||Highly toxic|
|Fenthion||Entex, Baytex, Baycid, Dalf, DMPT, Mercaptophos, Prentox, Fenthion 4E, Queletox,Lebaycid||Organophosphate||Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.||Highly toxic|
|Fonofos||Dyfonate EC||Organophosphate||3 hours||List of Schedule 2 substances (CWC)||Highly toxic|
|Malathion||Malathion USB, ~ EC, Cythion, maldison, mercaptothion||Organophosphate||>8 fl oz/acre (58 L/km2) ⇒ 5.5 days||Malathion is highly toxic to bees and other beneficial insects, some fish, and other aquatic life. Malathion is moderately toxic to other fish and birds, and is considered low in toxicity to mammals.||Highly toxic|
|Methamidophos||Monitor, Tameron||Organophosphate||Highly toxic|
|Methyl parathion||Parathion, Penncap-M||Organophosphate||5–8 days||It is classified as a UNEP persistent organic pollutant and WHO Toxicity Class, "Ia, Extremely Hazardous".||Highly toxic|
|Naled||Dibrom||Organophosphate||16 hours||Highly toxic|
|Oxydemeton-methyl||Metasystox-R||Organophosphate||<2 hours||Highly toxic|
|Phorate||Thimet EC||Organophosphate||5 hours||Highly toxic|
|Phosmet||Imidan||Organophosphate||Phosmet is very toxic to honeybees.||Highly toxic|
|Tetrachlorvinphos||Rabon, Stirofos, Gardona, Gardcide||Organophosphate||Highly toxic|
|Trichlorfon, Metrifonate||Dylox, Dipterex||Organophosphate||3 – 6 hours||Relatively nontoxic|
|Bifenthrin||Agri-Medk, Abamectin, Talstar, Bifenthrine, Brigade, Capture, FMC 54800, OMS3024, Torant (with Clofentezine), and Zipak (with Amitraz)||Pyrethroid||< 1 day RT
> 1 day ERT
|Permethrin||Ambush, Pounce||Pyrethroid||1 – 2 days||Safened by repellency under arid conditions. Permethrin is also the active ingredient in insecticides used against the Small hive beetle, which is a parasite of the beehive in the temperate climate regions.||Highly toxic|
|Cypermethrin||Ammo, Demon, Raid, Viper||Pyrethroid||Less than 2 hours||Cypermethrin is found in many household ant and cockroach killers, including Raid and ant chalk.||Highly toxic|
|Fenvalerate||Asana, Pydrin||Pyrethroid||1 day||Safened by repellency under arid conditions||Highly toxic|
|Resmethrin||Black Flag Mosquito Fog Solution, Chrysron, Crossfire, Pynosect, Raid Flying Insect Killer, Scourge, Sun-Bugger #4, SPB-1382, Synthrin, Syntox, Vectrin, Whitmire PT-110||Pyrethroid||Resmethrin is highly toxic to bees, with an LD50 of 0.063 ug/bee.||Highly toxic|
|Methoxychlor||DMDT, Marlate||Chlorinated cyclodiene||2 hours||available as a General Use Pesticide||Highly toxic|
|Endosulfan||Thiodan||Chlorinated cyclodiene||8 hours||Banned in EU (2007?), Banned in NZ (2009)||Moderately toxic|
|Clothianidin||Poncho||Neonicotinoid||Banned in EU for outdoor use since 2018.||Highly Toxic|
|Thiamethoxam||Actara||Neonicotinoid||Banned in EU for outdoor use since 2018.||Highly Toxic|
|Imidacloprid||Confidor, Gaucho, Kohinor, Admire, Advantage, K9 Advantix, Merit, Confidor, Hachikusan, Amigo, SeedPlus (Chemtura Corp.), Monceren GT, Premise, Prothor, Winner||Neonicotinoid||Banned in France since 1999. Banned in EU for outdoor use since 2018.||Highly toxic|
|Fipronil||Regent, Goliath, Nexa, Adonis, Termidor, Ultrathor, Fipforce, Taurus, Combat Ant-Rid, Anthem, Clearout, Radiate||Phenylpyrazole||Banned in EU for use on maize and sunflowers since 2014.||Highly toxic|
|Petroleum oils||Relatively nontoxic|
|2,4-D||Weed B Gon (also contains dicamba), ingredient in over 1,500 products||Synthetic auxin herbicide||Relatively nontoxic|
Highly toxic and banned in the US
- Aldrin Banned by US EPA in 1974.
- Dieldrin Banned by US EPA in 1974.
- Lindane, BHC Banned in California. Banned for agricultural use in the US by the EPA in 2006.
Based on a risks to bee health as identified by the European Food Safety Authority (EFSA), in April 2013 the EU decided to restrict the use of the neonicotinoids thiamethoxam, clothianidin, and imidacloprid. Fipronil was also banned for use on maize and sunflowers.
In 2015, the US Environmental Protection Agency (EPA) proposed to prohibit the application of certain pesticides and herbicides that are known to be toxic to bees during pollination periods when crops are in bloom. Seed treatments were not considered to present a risk to bee health. A modified form of these proposals was adopted as EPA policy in January 2017.
In April 2018, member states of the European Union agreed upon a total ban on neonicotinoid insecticide use, except within closed greenhouses. The vote on the proposed ban followed a February 2018 report from the EFSA which concluded that neonicotinoids posed a high risk to both domestic and wild bees. The ban had strong public support, but faced criticism from the agrochemical industry, and from certain farmers' groups.
In 2020, the EPA supplemented its policy with a proposal to restrict the use of neonicotinoids on residential lawns and turf, but otherwise confirmed that they would remain in use in the US.
General measures to prevent pesticide bee kills
Application of pesticides at evening or night
Avoiding the application of pesticides directly to blooming flowers can help limit the exposure of honeybees to toxic materials. If blooming flowers must be sprayed with pesticides for any reason, they should be sprayed in the evening or night hours when bees are not in the field. The usual foraging hours of honeybees are during the daytime when the temperature is above 55–60 °F (13–16 °C).
- Bees and toxic chemicals
- Colony Collapse Disorder
- United States Environmental Protection Agency
- Endangered arthropod
- Pesticide misuse
- Pollinator decline
- Imidacloprid effects on bees
- Honey bee starvation
- Ministry of Agriculture[dead link]
- "Protecting Pollinators from Pesticides - Bees, Beekeeping & Protecting Pollinators". Honey Bee Program. Retrieved July 24, 2021.
- Abrol, Dharam P. (5 October 2011). Pollination Biology: Biodiversity Conservation and Agricultural Production. ISBN 9789400719422.
- Carreck, Norman L (2014). "The dose makes the poison: have "field realistic" rates of exposure of bees to neonicotinoid insecticides been overestimated in laboratory studies?" (PDF). Journal of Apicultural Research. 53 (5): 607–614. doi:10.3896/IBRA.1.53.5.08. S2CID 15038464.
- "EU to fully ban neonicotinoid insecticides to protect bees". Reuters. 27 April 2018. Retrieved 29 April 2018.
- Naidu, Jennis (11 October 2019). "Paraquat, Imidacloprid Pesticide To Be Banned From January, 2020". Fiji Sun. Retrieved 23 July 2021.
-  Pollinator protection requirements for Section 18 Emergency Exemptions and Section 24(c) special local need registration in Washington State; Registration Services Program Pesticide Management Division Washington State Dept of Agriculture, Dec 2006[dead link]-
- Sanford 1993.
- [dead link]
- Pisa, Lennard; Goulson, Dave; Yang, En-Cheng; Gibbons, David; Sánchez-Bayo, Francisco; Mitchell, Edward; Aebi, Alexandre; Van Der Sluijs, Jeroen; MacQuarrie, Chris J. K; Giorio, Chiara; Long, Elizabeth Yim; McField, Melanie; Bijleveld Van Lexmond, Maarten; Bonmatin, Jean-Marc (2017). "An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: Impacts on organisms and ecosystems". Environmental Science and Pollution Research. 28 (10): 11749–11797. doi:10.1007/s11356-017-0341-3. PMC 7921077. PMID 29124633.
- Desneux, Nicolas; Decourtye, Axel; Delpuech, Jean-Marie (January 2007). "The Sublethal Effects of Pesticides on Beneficial Arthropods". Annual Review of Entomology. 52 (1): 81–106. doi:10.1146/annurev.ento.52.110405.091440. PMID 16842032.
- Fischer, Johannes; Müller, Teresa; Spatz, Anne-Kathrin; Greggers, Uwe; Grünewald, Bernd; Menzel, Randolf (2014). "Neonicotinoids Interfere with Specific Components of Navigation in Honeybees". PLOS ONE. 9 (3): e91364. doi:10.1371/journal.pone.0091364. PMC 3960126. PMID 24646521.
- Tosi, Simone; Démares, Fabien J; Nicolson, Susan W; Medrzycki, Piotr; Pirk, Christian W.W; Human, Hannelie (2016). "Effects of a neonicotinoid pesticide on thermoregulation of African honey bees (Apis mellifera scutellata)" (PDF). Journal of Insect Physiology. 93–94: 56–63. doi:10.1016/j.jinsphys.2016.08.010. hdl:2263/56625. PMID 27568395.
- Henry, Mickaël; Cerrutti, Nicolas; Aupinel, Pierrick; Decourtye, Axel; Gayrard, Mélanie; Odoux, Jean-François; Pissard, Aurélien; Rüger, Charlotte; Bretagnolle, Vincent (2015). "Reconciling laboratory and field assessments of neonicotinoid toxicity to honeybees". Proceedings of the Royal Society B: Biological Sciences. 282 (1819): 20152110. doi:10.1098/rspb.2015.2110. PMC 4685821. PMID 26582026.
- Tosi, Simone; Burgio, Giovanni; Nieh, James C (2017). "A common neonicotinoid pesticide, thiamethoxam, impairs honey bee flight ability". Scientific Reports. 7 (1): 1201. doi:10.1038/s41598-017-01361-8. PMC 5430654. PMID 28446783.
- Tosi, S; Nieh, J. C (2017). "A common neonicotinoid pesticide, thiamethoxam, alters honey bee activity, motor functions, and movement to light". Scientific Reports. 7 (1): 15132. doi:10.1038/s41598-017-15308-6. PMC 5680225. PMID 29123189.
- Williamson, Sally M; Willis, Sarah J; Wright, Geraldine A (2014). "Exposure to neonicotinoids influences the motor function of adult worker honeybees". Ecotoxicology. 23 (8): 1409–18. doi:10.1007/s10646-014-1283-x. PMC 4165879. PMID 25011924.
- USDA CCD Report
- Radunz, L. and Smith, E. S. C. Pesticides Hazard to Honey Bees Archived 2016-03-03 at the Wayback Machine Entomology, Darwin, Australia
- "Carbaryl". Extoxnet. Retrieved July 24, 2021.
- "Carbofuran". Extoxnet. August 1, 1994. Retrieved July 24, 2021.
- "Methomyl". Extoxnet. Retrieved July 24, 2021.
- "Propoxur". Extoxnet. Retrieved July 24, 2021.
- "acephate". Archived from the original on 2008-03-06. Retrieved 2005-02-18.
- "Acephate General Fact Sheet" (PDF). National Pesticide Information Center. 2011. Retrieved July 24, 2021.
- "Azinphos-methyl". Extoxnet. Retrieved July 24, 2021.
- Scott, Alex (August 4, 2008). "Europe Rejects Appeal for Use of Azinphos-methyl Pesticide". Chemical Week. Retrieved 2008-08-11.
- "Chlorpyrifos". Extoxnet. Retrieved July 24, 2021.
- coumaphos Archived February 5, 2005, at the Wayback Machine
- "Demeton-S-methyl". Extoxnet. Retrieved July 24, 2021.
- "Diazinon". Extoxnet. Retrieved July 24, 2021.
- "Dicrotophos". Extoxnet. Retrieved July 24, 2021.
- Clinch, P. G; Palmer-Jones, T; Forster, I. W (1973). "Effect on honey bees of dicrotophos and methomyl applied as sprays to white clover". New Zealand Journal of Experimental Agriculture. 1: 97–9. doi:10.1080/03015521.1973.10427625.
- "Dichlorvos". Extoxnet. Retrieved July 24, 2021.
- "Dimethoate". Extoxnet. Retrieved July 24, 2021.
- "Fenthion". Extoxnet. Retrieved July 24, 2021.
- "Fenitrothion". Extoxnet. Retrieved July 24, 2021.
- "Fonofos". Extoxnet. Retrieved July 24, 2021.
- "Methidathion". Extoxnet. Retrieved July 24, 2021.
- "Parathion". Extoxnet. Retrieved July 24, 2021.
- "Mevinphos". Extoxnet. Retrieved July 24, 2021.
- "Monocrotophos". Extoxnet. Retrieved July 24, 2021.
- "Naled". Extoxnet. Retrieved July 24, 2021.
- "Phorate". Extoxnet. Retrieved July 24, 2021.
- "Phosmet". Extoxnet. Retrieved July 24, 2021.
- "Toxicity of Pesticides to Pollinators and Beneficials". Center for Agriculture, Food and the Environment. January 25, 2017. Retrieved July 24, 2021.
- Krupke, Hunt & Foster 2021.
- "Bifenthrin". pmep.cce.cornell.edu. Retrieved 2018-09-25.
- "Permethrin". Extoxnet. Retrieved July 24, 2021.
- "Cypermethrin". Extoxnet. Retrieved July 24, 2021.
- "Esfenvalerate". Extoxnet. Retrieved July 24, 2021.
- "Resmethrin". Extoxnet. Retrieved July 24, 2021.
- "Active Ingredient Fact Sheets" (PDF). National Pesticide Information Center. November 9, 2015. Retrieved July 24, 2021.
- MSDS for Scourge' Formula II
- "Methoxychlor". Extoxnet. Retrieved July 24, 2021.
- "Endosulfan". Extoxnet. Retrieved July 24, 2021.
- EPA Clothianidin Reviews[dead link]
- The National Beekeepers’ Association of New Zealand - Submission on Application ERMA200886[dead link]
- Perry, Trent; Chan, Janice Q; Batterham, Phil; Watson, Gerald B; Geng, Chaoxian; Sparks, Thomas C (2012). "Effects of mutations in Drosophila nicotinic acetylcholine receptor subunits on sensitivity to insecticides targeting nicotinic acetylcholine receptors". Pesticide Biochemistry and Physiology. 102: 56–60. doi:10.1016/j.pestbp.2011.10.010.
- "2,4-D". Extoxnet. Retrieved July 24, 2021.
- Aldrin[dead link]
- dieldrin[dead link]
- "Heptachlor". Extoxnet. Retrieved July 24, 2021.
- Moroni, Flavio; Russi, Patrizia; Gallo-Mezo, Miguel Angel; Moneti, Gloriano; Pellicciari, Roberto (1991). "Modulation of Quinolinic and Kynurenic Acid Content in the Rat Brain: Effects of Endotoxins and Nicotinylalanine". Journal of Neurochemistry. 57 (5): 1630–5. doi:10.1111/j.1471-4159.1991.tb06361.x. PMID 1833509. S2CID 12613550.
- "Addendum to the 2002 Lindane Reregistration Eligibility Decision (RED)" (PDF). US Environmental Protection Agency. 2006. Retrieved 23 July 2021.
- Torello, Alessandro; Haddon, Michael (April 29, 2013). "EU to Restrict 'Bee-Harming' Pesticides". WSJ. Retrieved July 24, 2021.
- "Policy Mitigating Acute Risk to Bees from Pesticide Products". US EPA. May 28, 2015. Retrieved July 20, 2021.
- Butler, Declan (February 28, 2018). "EU expected to vote on pesticide ban after major scientific review". Nature. 555 (7695): 150–151. doi:10.1038/d41586-018-02639-1. Retrieved July 20, 2021.
- Carrington D. "EU agrees total ban on bee-harming pesticides". The Guardian. Archived from the original on 27 April 2018. Retrieved 27 April 2018.
- "Proposed Interim Registration Review Decision for Neonicotinoids". US EPA. January 30, 2020. Retrieved July 20, 2021.
- Ellis, Baxendale & Keith 1998.
- "Honey Bees and Pesticides". Mid-Atlantic Apiculture Research and Extension Consortium. 1978. Archived from the original on 11 March 2007. Retrieved 23 July 2021.
- Hooven L, Sagili R, Johansen E (2016). "How to Reduce Bee Poisoning from Pesticides". Oregon State University. Retrieved 23 July 2021.
- Mayer DF, Johansen CA, Baird CR (1999). "How to Reduce Bee Poisoning from Pesticides" (PDF). Washington State University. Archived from the original (PDF) on 4 February 2007. Retrieved 23 July 2021.
- McBride DK (1997). "Protecting Honeybees From Pesticides". North Dakota State University. Retrieved 23 July 2021.
- Sanford MT (1993). "Protecting Honey Bees From Pesticides". University of Florida.[dead link]
- Krupke CH, Hunt G, Foster RE (2021). "Protecting honey bees from pesticides" (PDF). University of Purdue. Retrieved 23 July 2021.
- Ellis MD, Baxendale FP, Keith DL (1998). "Protecting Bees When Using Insecticides". University of Nebraska Lincoln, Extension. Archived from the original on 8 February 2005. Retrieved 23 July 2021.
- US EPA Pesticide Registration (PR) Notice 2001-5[dead link]
- Bee Health: Background and Issues for Congress Congressional Research Service
- Bee Health: The Role of Pesticides Congressional Research Service
- "The Xerces Society for Invertebrate Conservation". Retrieved July 24, 2021.