Pesticides vary in their effect on bees. Contact insecticides affect the worker bee that is directly sprayed. Systemic insecticides can contaminate nectar or pollen and cause bee kills in the hive.
Dusts and wettable powders tend to be more hazardous to bees than solutions or emulsifiable concentrates.
Classification of toxicity based on Lethal Dose 50% (LD50)mg/bee
- >100 virtually non-toxic
- 11-100 slightly toxic
- 2.0-10.99 moderately toxic
- <2.0 highly toxic
Bee kill rate
The kill of bees can be classified as:
- <100 per day - normal die off rate
- 200-400 per day - low kill
- 500-900 per day - moderate kill
- >1000 per day - high kill
Highly Toxic
Brand name, generic name and length of residual toxicity. Note that the brand names listed here are by no means complete.
- Afugan (pyrazophos)
- Azodrin (monocrotophos)
- Baytex (fenthion)
- Bidrin (dicrotophos)
- Cygon (dimethoate) ⇒ 3 days banned in the US
- Cythion (malathion)
- Dasanit ([fensulfothion])
- DDVP (dichlorvos)
- De-Fend (dimethoate)
- Dibrom (naled) ⇒ 16 hours
- Dursban (chlorpyrifos) banned in the US for home and garden use
- Dyfonate EC (fonofos) ⇒ 3 hours
- Gardona (tetrachlorvinphos )
- Guthion (azinphos-methyl) ⇒ 2.5 days
- Imidan phosmet
- Lorsban (chlorpyrifos) banned in the US for home and garden use ⇒ 4 - 6 days
- malathion
- Malathion USB >8 fl oz/acre (58 L/km²) ⇒ 5.5 days
- Malathion EC ⇒ 2-6 hours
- Metasystox-R (oxydemetonmethy]) ⇒ <2 hours
- Methyl-Guthion (azinphos-methyl)
- Monitor (methamidophos)
- parathion Penncap-M (methyl parathion) ⇒ 5-8 days. By far the most potentially damaging pesticides for honey bees are those packaged in tiny capsules (microencapsulated). Microencapsulated methyl parathion (PennCap MŽ), 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 that this formulation be used only when honey bee exposure is not a possibility.
- Sevin (carbaryl) ⇒ 3 - 7 days
- Sevin XLR (carbaryl) ⇒ 8 hours @ 1.5 lb/acre (168 kg/km²) or less. Bees poisoned with carbaryl can take 2-3 days to die and appear inactive as if cold. It allows them time to take contaminated nectar and pollen back to the colony. Some crops treated with SevinŽ under the wrong conditions (i.e., in bloom using a dust formulation with large numbers of bees in the field) have been responsible for disastrous kills. SevinŽ is one of the US 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. 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 SevinŽ poisoning.
- Spectracide (diazinon)
- Sumithion (fenitrothion)
- Supracide (methidathion)
- Tameron (methamidophos)
- Thimet EC (phorate) ⇒ 5 hours
- Vapona (dichlorvos)
Synthetic pyrethroids
- Ambush (permethrin) ⇒ 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.
- Ammo (cypermethrin) ⇒ Less than 2 hours
- Asana (esfenvalerate) ⇒ 1 day, safened by repellency under arid conditions
- Pounce (permethrin) ⇒ 1 - 2 days, safened by repellency under arid conditions
- Pydrin (esfenvalerate) ⇒ 6 hours
- resmethrin
Chlorinated cyclodienes
Chloronicotines
Others
- Dimecron (phosphamidon )
- Famophos (famphur )
- Phosdrin (mevinphos)
- phosphamidon (Dimecron )
- Systox (demeton) ⇒ <2 hours
- tepp most toxic to bees LD50 0.001 micrograms per bee but short residual activity*Zectran (mexacarbate) formula
Source:Protecting Bees When Using Insecticides University of Nebraska Lincoln, Extension, May 1998
Highly toxic and banned in the US
Moderately toxic
- Orthene (acephate) ⇒ 3 days
- demeton-s-methyl
Relatively non-toxic
- Most fungicides and herbicides
- Checkmite (coumaphos) This is an organo phosphate insecticide that is used inside the beehive to combat varroa mites and small hive beetle , which are parasites of the honey bee. Overdoses can lead to bee poisoning .
- Endosulfan
- dicofol
- pirimicarb,
- petroleum oils
- most pyrethroid chemicals
- Temik (aldicarb ) ⇒ apply 4 weeks before bloom
- Dylox (trichlorfon ) ⇒ 3 - 6 hours
This list is incomplete. Please add to it.
Common insecticides toxic to bees used on soybeans
Many insecticides used against soybean aphids are highly toxic to bees.
- 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)
Source: Commonly Used Insecticides for Soybeans Kansas State University Extension, Aug 2004
External links