Pesticide toxicity to bees

Template:Short description 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref>Template:Cite journal</ref>

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.<ref name="ent.uga.edu">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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.<ref>Template:Cite book</ref>

Pesticides, especially neonicotinoids, have been investigated in relation to risks for bees such as Colony Collapse Disorder. A 2018 review by the European Food Safety Authority (EFSA) concluded that most uses of neonicotinoid pesticides such as clothianidin represent a risk to wild bees and honeybees.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref><ref name="EFSA2">Template:Cite journal</ref> Neonicotinoids have been banned for all outdoor use in the entire European Union since 2018, but has a conditional approval in the U.S. and other parts of the world, where it is widely used.<ref>Template:Cite news</ref><ref>Template:Cite news</ref>

Classification

Insecticide toxicity is generally measured using acute contact toxicity values Template:LD50 – the exposure level that causes 50% of the population exposed to die. Toxicity thresholds are generally set at<ref>http://www.agr.wa.gov/pestfert/Pesticides/docs/PollinatorSLNSect18.pdf Template:Webarchive 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</ref>Template:Sfn

• highly toxic (acute LD50 < 2μg/bee)
• moderately toxic (acute LD50 2 – 10.99 μg/bee)
• slightly toxic (acute LD50 11 – 100 μg/bee)
• nontoxic (acute LD50 > 100 μg/bee) to adult bees.

Pesticide toxicity

Acute toxicity

The acute toxicity of pesticides on bees, which could be by contact or ingestion, is usually quantified by Template: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.<ref>Template:Cite journal</ref> The acute toxicity, although more lethal, is less common than sub-lethal toxicity or cumulative effects.<ref>Template:Cite report</ref>

Sublethal and chronic effects

Field exposure to pesticides, especially with relation to neonicotinoids,<ref>Template:Cite journal</ref> may lead to multiple physiological and/or behavioral sublethal effects in exposed bees.<ref>Template:Cite journal</ref> Sublethal effects to honey bees can include disruptions to behavioral and motor functions, compromised immunity, and delayed development.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

Colony collapse disorder

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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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

Bee kill rate per hive

The kill rate of bees in a single bee hive can be classified as:<ref>Radunz, L. and Smith, E. S. C. Pesticides Hazard to Honey Bees Template:Webarchive Entomology, Darwin, Australia</ref>

< 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

Pesticide formulations

Pesticides come in different formulations:<ref name="ent.uga.edu"/>

• Dusts (D)
• Wettable powders (WP)
• Soluble powders (SP)
• Emulsifiable concentrates (EC)
• Solutions (LS)
• Granulars (G)

Pesticides

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
Carbaryl<ref name="Extoxnet Carbaryl">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Sevin, (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<ref name="Extoxnet Carbofuran">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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)<ref name="Extoxnet Carbofuran"/>	Highly toxic
Methomyl<ref name="Extoxnet Methomyl">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Lannate, Nudrin	Carbamate	2 hours	Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.	Highly toxic
Methiocarb	Mesurol	Carbamate			Highly toxic
Mexacarbate<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Zectran	Carbamate			Highly toxic
Pirimicarb	Pirimor, Aphox	Carbamate			Relatively nontoxic
Propoxur<ref name="Extoxnet Propoxur">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Baygon	Carbamate		Propoxur is highly toxic to honey bees. The LD50 for bees is greater than one ug/honey bee.Template:Citation needed	Highly toxic
Acephate<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Orthene	Organophosphate	3 days	citation	CitationClass=web }}</ref>	Moderately toxic
Azinphos-methyl<ref name="Extoxnet Azinphos-methyl">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Guthion, Methyl-Guthion	Organophosphate	2.5 days	Banned in EU since 2006.<ref>Template:Cite news</ref>	Highly toxic
Chlorpyrifos<ref name="Extoxnet Chlorpyrifos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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<ref>coumaphos Template:Webarchive</ref>	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<ref name="Extoxnet Demeton-S-methyl">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Meta-systox	Organophosphate		Banned worldwide for toxicity to humans	Moderately toxic
Diazinon<ref name="Extoxnet Diazinon">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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<ref name="Extoxnet Dicrotophos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Bidrin	Organophosphate		Dicrotophos toxicity duration is about one week.<ref>Template:Cite journal</ref>	highly toxic
Dichlorvos<ref name="Extoxnet Dichlorvos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	DDVP, Vapona	Organophosphate			Highly toxic
Dimethoate<ref name="Extoxnet Dimethoate">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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<ref name="Extoxnet Fenthion">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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
Fenitrothion<ref name="Extoxnet Fenitrothion">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Sumithion	Organophosphate			Highly toxic
Fensulfothion	Dasanit	Organophosphate			Highly toxic
Fonofos<ref name="Extoxnet Fonofos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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	citation	CitationClass=web }}</ref>	Highly toxic
Methamidophos<ref name="Extoxnet Methamidophos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Monitor, Tameron	Organophosphate		Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.	Highly toxic
Methidathion<ref name="Extoxnet Methidathion">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Supracide	Organophosphate		Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.	Highly toxic
Methyl parathion	Parathion,<ref name="Extoxnet Parathion">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref> Penncap-M	Organophosphate	5–8 days	It is classified as a UNEP persistent organic pollutant and WHO Toxicity Class, "Ia, Extremely Hazardous".Template:Citation needed	Highly toxic
Mevinphos<ref name="Extoxnet Mevinphos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Phosdrin	Organophosphate			highly toxic
Monocrotophos<ref name="Extoxnet Monocrotophos">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Azodrin	Organophosphate		Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.	Highly toxic
Naled<ref name="Extoxnet Naled">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Dibrom	Organophosphate	16 hours		Highly toxic
Omethoate		Organophosphate		Should never be sprayed on flowering crops especially if bees are active and the crop requires pollination.	Highly toxic
Oxydemeton-methyl<ref name="Extoxnet DEMETON-S-METHYL">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Metasystox-R	Organophosphate	<2 hours		Highly toxic
Phorate<ref name="Extoxnet Phorate">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Thimet EC	Organophosphate	5 hours		Highly toxic
Phosmet<ref name="Extoxnet Phosmet">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Imidan	Organophosphate		citation	CitationClass=web }}</ref>	Highly toxic
Phosphamidon	Dimecron	Organophosphate			Highly toxic
Pyrazophos	Afugan	Organophosphate	Fungicide		Highly toxic
Tetrachlorvinphos	Rabon, Stirofos, Gardona, Gardcide	Organophosphate			Highly toxic
Trichlorfon, Metrifonate	Dylox, Dipterex	Organophosphate		3 – 6 hours	Relatively nontoxic
Bifenthrin<ref name="Center for Agriculture, Food and the Environment 2017">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>Template:Sfn	citation	CitationClass=web }}</ref>	Pyrethroid	< 1 day RT > 1 day ERT		Highly toxic
Permethrin<ref name="Extoxnet Permethrin">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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<ref name="Extoxnet Cypermethrin">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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<ref name="Extoxnet Esfenvalerate">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Asana, Pydrin	Pyrethroid	1 day	Safened by repellency under arid conditions	Highly toxic
Resmethrin<ref name="Extoxnet Resmethrin">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref><ref name="NPIC ResTech">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref><ref>MSDS Template:Webarchive for Scourge Formula II</ref>	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.Template:Citation needed	Highly toxic
Methoxychlor<ref name="Extoxnet Methoxychlor">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	DMDT, Marlate	Chlorinated cyclodiene	2 hours	available as a General Use Pesticide	Highly toxic
Endosulfan<ref name="Extoxnet Endosulfan">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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.	citation	CitationClass=web }}</ref>
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
Sulfoxaflor		Sulfoximine		citation	CitationClass=web }}</ref><ref>Template:Cite journal</ref>
Dicofol		Acaricide			Relatively nontoxic
Petroleum oils					Relatively nontoxic
2,4-D<ref name="Extoxnet 2,4-D">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	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.<ref>{{#invoke:citation/CS1|citation

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• Dieldrin Banned by US EPA in 1974.<ref>{{#invoke:citation/CS1|citation

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• Heptachlor<ref name="Extoxnet">{{#invoke:citation/CS1|citation

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• Lindane, BHC Banned in California.<ref name=pmid1833509>Template:Cite journal</ref> Banned for agricultural use in the US by the EPA in 2006.<ref>{{#invoke:citation/CS1|citation

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Regulatory policy

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.<ref name="Torello Haddon 2013">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Fipronil was also banned for use on maize and sunflowers.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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.<ref name="US EPA 2015">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

In April 2018, member states of the European Union agreed upon a total ban on neonicotinoid insecticide use, except within closed greenhouses.<ref name="Reuters2018">Template:Cite news</ref> 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.<ref name="Nature 2018">Template:Cite journal</ref> The ban had strong public support, but faced criticism from the agrochemical industry, and from certain farmers' groups.<ref name="Guardian2018">Template:Cite news</ref>

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.<ref name="US EPA 2020">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

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 Template:Cvt.<ref name="ent.uga.edu"/>Template:SfnTemplate:Sfn

See also

• Bees and toxic chemicals
• Colony collapse disorder
• Endangered arthropod
• Fipronil
• Honey bee starvation
• Imidacloprid effects on bees
• Neonicotinoids
• Pesticide misuse
• Pesticides
• Pollination
• Pollinator decline
• United States Environmental Protection Agency

External links

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• US EPA Pesticide Registration (PR) Notice 2001-5 Template:Webarchive
• Bee Health: Background and Issues for Congress Template:Webarchive Congressional Research Service
• Bee Health: The Role of Pesticides Template:Webarchive Congressional Research Service
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