Relative toxicity of pesticides

Honeybees react differently to different pesticides, and most herbicides and fungicides are less toxic to bees than are insecticides. To the beekeeper, the most obvious sign of pesticide poisoning is the presence of an exceptional number of dead bees in front of the hives. The following figures have been established as guidelines for assessing the extent of pesticide poisoning: 100 dead bees per day is the colony's normal death rate; 200-400 dead bees indicate a low level of pesticide poisoning; 500-1000 dead bees indicate a medium level of pesticide poisoning; over 1000 dead bees indicate a high level of pesticide poisoning.

As indicated above, pesticide application is one of the most important inputs to agriculture. Understanding and cooperation among growers and beekeepers are essential to prevent, or at least to minimize, the loss of honeybees due to the toxic effects of pesticides. The following table lists the most common pesticides, indicating their relative toxicity to honeybees.

Relative Toxicity of Pesticides to the Common Honeybee

Group 1 - Highly Toxic

The application of these pesticides to foraging areas when bees are active may cause severe damage. Beekeepers must know in advance when they are to be used and take special precautions; moving colonies out of the area temporarily is perhaps the safest approach.

Group 2 - Moderately Toxic

These products should not he applied directly on fields when bees are actively foraging or when hives are exposed. Dose, timing and application methods are among factors determining whether the pesticides can he used with minimum risk to bees.

Group 3 - Relatively Non-Toxic

These products can be used on fields or near hives with minimum damage to bees; in fact, a few of the listed acaricides can he used to control bee mites within the hive.

A. INSECTICIDES AND ACARICIDES

B. FUNGICIDES

C. HERBICIDES