Protecting Honeybees from Pesticide Poisoning

Gary W. Gibson
Assistant Director
Plant Industries Division
West Virginia Department of Agriculture
(304) 558-2212

Reprinted from The Market Bulletin , Volume 81, No. 3, March 1997

Honeybees are some of our most beneficial insects, yet most of us probably take them for granted. Not only do they produce a surplus of honey and beeswax, they are almost indispensable in the pollination of such important crops as apples, blueberries, sunflowers, melons and cucumbers.
While there are many different kinds of insects that are capable of pollinating crops, only honeybees are available on a large-scale basis for nationwide pollination services.

Agriculture officials, fruit and vegetable producers and beekeepers are concerned about a decline in honeybee populations that has been occurring in many areas of the country, including West Virginia. Two parasitic mites, the Varroa mite and the honeybee tracheal mite, are responsible for most of the decline in both our wild and domestic honeybee colonies.

However, each year, additional honeybee colonies are adversely affected, not by parasitic mites or infectious bee diseases, but from the effects of pesticide contamination. Honeybees can be exposed to pesticides in several ways. Worker bees gathering nectar and pollen may be directly exposed to pesticides or they may carry pesticide-contaminated pollen back to the hive and expose other honeybees. Contaminated pollen may even be stores in the hive and cause problems months later.

Pesticide applicators can help protect honeybees and other nontarget organisms from pesticide injury by obeying the pesticide label directions, using good judgment and following a few simple safety rules.

• Certain methods of applying pesticides, such as aerial applications or the use of dust formulations, present a high degree of risk to honeybees and nontarget organisms. Honeybees may fly directly into the pesticide or the chemical may drift onto flowering weeds that are adjacent to the target crop. Use pesticides only when necessary and avoid high-hazard methods of applying pesticides.
• Before applying pesticides, remove any flowering weeds that attract bees, such as dandelions, asters, mustard, sweet clover, milkweed and goldenrod.
• Apply pesticides only when bees are not present. Honeybee activity is usually greatest in the morning and diminishes in the evening. Also, there is usually less wind in the evening, which means less chance of pesticide drift. Do not spray corn tassels, either, because bees are likely to be gathering pollen from them.
• It is likely that a beekeeper lives within a two-mile flying range of your garden and his or her honeybees pollinate your fruits and vegetables. Get to know your local beekeepers and notify them before you apply pesticides so that beehives may be moved, if necessary.
• Some pesticides are labeled "highly toxic to honeybees." If possible, select a pesticide that is less toxic to honeybees and use sprays instead of dust formulations. Insecticidal soaps, rotenone and the bacterial insecticide Bacillus thuringiensis(Dipel, Thuricide, Bt) are not harmful to honeybees.

The following may indicate that a beehive has been contaminated with a pesticide.

• Finding dead bees in front of the hive for a few days.
• Bees crawling away from the hive and dying.
• Within the hive, a break in the brood cycle (stages of young bees) or a spotty pattern of the brood could also indicate a pesticide problem.
• Bees that have been exposed to a pesticide may regurgitate a thick, dark fluid.