Pesticide toxicity to bees

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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.

Actual damage to bee populations is a function of the degree of toxicity of the compound in combination with the mode of application; a highly potent insecticide applied only to the soil, for instance, would be expected to kill mainly soil-dwelling insects such as grubs or mole crickets, and not bees.

Contents

[edit] Classification of toxicity based on Lethal Dose 50% (LD50)mg/bee

>100 mg/bee virtually non-toxic
11-100 mg/bee slightly toxic
2.0-10.99 mg/bee moderately toxic
<2.0 mg/bee highly toxic

[edit] Bee kill rate per hive

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

[edit] Highly Toxic Pesticides to Bees

Listed by brand name, generic name and length of residual toxicity. Note that the brand names listed here are by no means complete.

[edit] Carbamates

[edit] Organophosphates

  • 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 [1]) 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 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 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 Sevin® 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. Sevin® 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 Sevin® poisoning.
  • Spectracide (diazinon)
  • Sumithion (fenitrothion)
  • Supracide (methidathion)
  • Tameron (methamidophos)
  • Thimet EC (phorate) ⇒ 5 hours
  • Vapona (dichlorvos)

[edit] Synthetic pyrethroids

[edit] Chlorinated cyclodienes

[edit] Chloronicotines

[edit] Herbicides

[edit] 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

[edit] Highly toxic and banned in the US

[edit] Moderately toxic

  • Orthene (acephate) ⇒ 3 days
  • demeton-s-methyl
This list is incomplete; you can help by expanding it.

[edit] Relatively non-toxic

This list is incomplete; you can help by expanding it.

[edit] 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

[edit] External links

[edit] See also

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