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 media. 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.
Dust and wettable powder pesticides tend to be more hazardous to bees than solutions or emulsifiable concentrates for contact pesticides.
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.
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.
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 CCD have been proposed, but no one primary cause has been found. The US Department of Agriculture (USDA) has indicated in a report to Congress that a combination of factors may be causing CCD, including pesticides, pathogens, and parasites, all of which have been found at high levels in affected bee hives.
For the majority of pesticides that are registered in the United States, EPA only requires a short-term contact toxicity test on adult honeybees. In some cases, the agency also receives short-term oral toxicity tests, which are required in Europe. EPA's testing requirements do not account for sub-lethal effects to bees or effects on brood or larvae. Their testing requirements are also not designed to determine effects in bees from exposure to systemic pesticides. With Colony Collapse Disorder, whole hive tests in the field are needed in order to determine the effects of a pesticide on bee colonies. To date, there are very few scientifically valid whole hive studies that can be used to determine the effects of pesticides on bee colonies.
A March 2012 study conducted in Europe, in which minuscule electronic localization devices were fixed on bees, has shown that, even with very low levels of pesticide in the bee's diet, a high proportion of bees (more than one third) suffers form orientation disorder and is unable to come back to the hive. The pesticide concentration was order of magnitudes smaller than the lethal dose used in the pesticide's current use. The pesticide under study, brand-named "Cruiser" in Europe (Thiamethoxam, a Neonicotinoid insecticide), although allowed in France by annually renewed exceptional authorization, could be banned in the coming years by the European Commission.
April 2013 the EU decided to restrict thiamethoxam, clothianidin, and imidacloprid.
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
|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. It allows them time to take contaminated nectar and pollen back to the colony. Some crops treated with Sevin under the wrong conditions (in bloom, using a dust formulation, with large numbers of bees in the field) have been responsible for disastrous kills. Sevin is one of the United States' most widely used insecticides for a wide variety of insect pests. It is also one of the most toxic to honey bees, in certain formulations. These should never be sprayed on flowering crops especially if bees are active and the crop requires pollination. There are formulations, however, which are determined to be less toxic (see tables). Usually, applicator-beekeeper communication can effectively be used to adequately protect bees from Sevin poisoning.||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|
|Acephate||Orthene||Organophosphate||3 days||Moderately toxic|
|Azinphos-methyl||Guthion, Methyl-Guthion||Organophosphate||2.5 days||banned in the European Union since 2006.||highly toxic|
|Chlorpyrifos||Dursban, Lorsban||Organophosphate||banned in the 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|
|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|
|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||highly toxic|
|Methamidophos||Monitor, Tameron||Organophosphate||highly toxic|
|Methyl parathion||Parathion, Penncap-M||Organophosphate||5–8 days||By far the most potentially damaging pesticides for honey bees are those packaged in tiny capsules (microencapsulated). Microencapsulated methyl parathion (PennCap M), for example, is a liquid formulation containing capsules approximately the size of pollen grains, which contain the active ingredient. When bees are out in the field, these capsules can become attached electrostatically to the pollen-collecting hairs of the insects, and at times are collected by design. When stored in pollen, the slow-release feature of the capsules allows the methyl parathion to be a potential killer for several months. At the present time, there is no way to detect whether bees are indeed poisoned by micro-encapsulated methyl parathion, so a beekeeper potentially could lose replacement bees for those already poisoned by the pesticide. It is, therefore, strongly recommended by experts that this formulation be used only when honey bee exposure is not a possibility.||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|
|Tetrachlorvinphos||Rabon, Stirofos, Gardona, Gardcide||Organophosphate||highly toxic|
|Trichlorfon, Metrifonate||Dylox, Dipterex||Organophosphate||3 – 6 hours||Relatively nontoxic|
|Permethrin||Ambush, Pounce||Synthetic 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, Raid||Synthetic 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||Synthetic pyrethroid||1 day||safened by repellency under arid conditions||highly toxic|
|Resmethrin||Chrysron, Crossfire, Pynosect, Raid Flying Insect Killer, Scourge, Sun-Bugger #4, SPB-1382, Synthrin, Syntox, Vectrin, Whitmire PT-110||Synthetic pyrethroid||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 European Union (2007?), New Zealand (2009)||moderately toxic|
|Clothianidin||Poncho||Neonicotinoid||Banned in Germany
In June 2008, the Federal Ministry of Food, Agriculture and Consumer Protection (Germany) suspended the registration of eight neonicotinoid pesticide seed treatment products used in oilseed rape and sweetcorn, a few weeks after honey bee keepers in the southern state of Baden Württemberg reported a wave of honey bee deaths linked to one of the pesticides, clothianidin.
|Thiamethoxam||Actara||Neonicotinoid||Clothianidin is a major metabolite of Thiamethoxam. A two year study published in 2012 showed the presence of clothianidin and thiamethoxam in bees found dead in and around hives situated near agricultural fields. Other bees at the hives exhibited tremors and uncoordinated movement and convulsions, all signs of insecticide poisoning.||Highly Toxic|
|Imidacloprid||Confidor, Gaucho, Kohinor, Admire, Advantage, Merit, Confidor, Hachikusan, Amigo, SeedPlus (Chemtura Corp.), Monceren GT, Premise, Prothor, and Winner||Neonicotinoid||(see also Imidacloprid effects on bee population)Banned in France since 1999||highly toxic|
|Petroleum oils||Relatively nontoxic|
|2,4-D||ingredient in over 1,500 products||Synthetic auxin herbicide||Relatively nontoxic|
Common insecticides toxic to bees and used on soybeans
- Orthene 75S (acephate)
- Address 75 WSP (acephate)
- Sevin (Carbaryl)
- Lorsban 4E (Chlorpyrifos)
- Dimate (Dimethoate)
- Steward 1.25 SC (Indoxacarb)
- Lannate (Methomyl)
- Cheminova Methyl 4EC (Methyl Parathion)
- Penncap M (microencapsulated Methyl Parathion)
- Tracer (Spinosad)
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)
Lawsuit against the EPA in the United States
In August 2008, the Natural Resources Defense Council, a New York environmental advocacy group, filed a lawsuit against the federal Environmental Protection Agency accusing the agency of withholding information about the risks pesticides pose to honeybees.
- Bees and toxic chemicals
- Colony Collapse Disorder
- Endangered arthropod
- Pesticide misuse
- Pollinator decline
- Imidacloprid effects on bees
- Ministry of Agriculture
- Ecological Risk Assessment
- University of Georgia Cooperative Extension
-  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
- Hunt, G.J.; Using honey bees in pollination Purdue University, May 2000
- USDA CCD Report
- Non-target insect testing
- Henry, M.; Beguin, M.; Requier, F.; Rollin, O.; Odoux, J. -F.; Aupinel, P.; Aptel, J.; Tchamitchian, S.; Decourtye, A. (2012). "A Common Pesticide Decreases Foraging Success and Survival in Honey Bees". Science 336 (6079): 348–350. doi:10.1126/science.1215039.
- EU to Restrict 'Bee-Harming' Pesticides April 29, 2013 Wall Street Journal
- Radunz, L. and Smith, E. S. C. Pesticides Hazard to Honey Bees Entomology, Darwin, Australia
- The National Beekeepers’ Association of New Zealand - Submission on Application ERMA200886
- Effects of mutations in Drosophila nicotinic acetylcholine receptor subunits on sensitivity to insecticides targeting nicotinic acetylcholine receptors
- Scott, Alex (August 4, 2008). "Europe Rejects Appeal for Use of Azinphos-methyl Pesticide". Chemical Week. Retrieved 2008-08-11.
- Resmethrin Technical Fact Sheet - National Pesticide Information Center
- Pyrethrins and Pyrethroids Fact Sheet - National Pesticide Information Center
- Resmethrin Pesticide Information Profile - Extension Toxicology Network
- MSDS for Scourge' Formula II
- EFSA report of 16 january 2013 labelling clothianidin, imidacloprid and thiamethoxam asdetrimental to bees
- "Emergency Pesticide Ban for Saving the Honeybee"
- EPA Clothianidin Reviews
- Protecting Bees When Using Insecticides University of Nebraska Lincoln, Extension, May 1998
- Commonly Used Insecticides for Soybeans Kansas State University Extension, Aug 2004
- EPA sued after allegations Bayer pesticide killing honeybees
- " Productivist Agriculture: Who wants to kill the bees?" by Henri Clément, President of the French Beekeepers’ Association (UNAF)
- "Who wants to kill the bees ? (It’s difficult to work it out)" by Jean-Luc Brunet, Assistant Manager of the Combined Bee Research and Environment Unit
- Honey Bees and Pesticides, 1978, Mid-Atlantic Apiculture Research and Extension Consortium
- http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/20772/pnw591.pdf How to Reduce Bee Poisoning from Pesticides PNW 591, A Pacific Northwest Extension Publication, Washington, Oregon, Idaho, Copyright 2006, Oregon State University. Revision of the WSU 1999 version of the same publication.
- Mayer, D.F., Johansen, C.A. & Baird, C.R.; How to Reduce Bee Poisoning from Pesticides, PNW518, A Pacific Northwest Extension Publication, Washington, Oregon, Idaho, Copyright 1999 Washington State University. Includes an extensive list of toxic chemicals such as pesticides that affect bees.
- McBride, Dean k.; Protecting Honeybees From Pesticides, 1997 North Dakota State University
- Sanford, Malcolm T.; Protecting Honey Bees From Pesticides, University of Florida Institute of Food and Agricultural Sciences Extension, April 1993
- US EPA Pesticide Registration (PR) Notice 2001-5
- Bee Health: Background and Issues for Congress Congressional Research Service
- Bee Health: The Role of Pesticides Congressional Research Service