Pesticide toxicity to bees

Further information: Colony Collapse Disorder

Pesticides vary in their effect on bees. Contact insecticides, those which kill by touching the organism, affect the worker bee that is directly sprayed. Systemic insecticides, those that are incorporated by treated plants, can contaminate nectar or pollen, and kill bees 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.

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Classification of pesticide toxicity

Insecticide toxicity is generally measured using LD50 - the exposure level that causes 50% of the population exposed to die. Toxicity thresholds are generally set at

• highly toxic (acute LD50 less than 2μg/bee)
• moderately toxic (acute LD50 2ug/bee to 10.99μg/bee)
• slightly toxic (acute LD50 11ug/bee to 100μg/bee)
• practically non-toxic (acute LD50 more than 100μg/bee) to adult bees.

^{[1] [2]}

LD50 is an incomplete measure of toxicity to bees and other social insects because it is a measure of individual toxicity, not colony toxicity. It does not account for the ways in which bee behavior can mitigate or exacerbate the effects of the pesticide on the colony. For example, a moderate to low toxicity pesticide (by LD50 measurement) which is used in granular form and is collected and concentrated along with pollen can be highly lethal to the colony. On the other hand, a pesticide which is so toxic that the exposed bees die in the field can be less dangerous to the colony than a less toxic pesticide which allows the exposed bees to return to the hive and contaminate their fellows. Likewise, a highly toxic pesticide (according to LD50 measures) is "safe" for bees if it is applied on a grass lawn or other location without blooming flowers which would attract the bees. Furthermore, LD50 studies are conducted against adult bees and do not measure the effects on larvae, etc.

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

Bee Toxic Pesticides

Highly toxic and banned in the US

• Aldrin banned by US EPA in 1974
• carbofuran (banned in granular form)
• dieldrin banned by US EPA in 1974
• heptachlor
• lindane, BHC (banned in California)

Source: Protecting Bees When Using Insecticides University of Nebraska Lincoln, Extension, May 1998

Common insecticides toxic to bees and 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)

See also

• Bees and toxic chemicals
• Colony Collapse Disorder
• Endangered arthropod
• Pesticide misuse
• Pollinator decline

References

1. ^ [1] 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
2. ^ Hunt, G.J.; Using honey bees in pollination Purdue University, May 2000

Sources

• Commonly Used Insecticides for Soybeans Kansas State University Extension, Aug 2004

External links

• Honey Bees and Pesticides, 1978, Mid-Atlantic Apiculture Research and Extension Consortium
• 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