“Pesticide” is the general term used for chemicals that target and kill pests like insects (insecticide), mites (miticide), weeds (herbicide), bacteria (bactericide) and fungi (fungicide). However, many of these are also toxic to bees. Each year, a lot of honeybee colonies are damaged or destroyed by these chemicals. This is a devastating impact on beekeepers, who might even have to relocate damaged hives. Some can also go out of business. Growers of insect-pollinated crops may experience lower yields, which in turn raises food prices.
Potential Factors for Honey Bee Damage:
Bee safe pesticides are determined by many factors:
1. Plant Growth Stage: Devastating bee poisoning results from spraying insecticides on flowering plants. They are not recommended for blooming crops.
2. Relative Toxicity of the Chemical: Pesticides vary in bee toxicity to honey bees. Most of the fungicides, herbicides and miticides are nontoxic, and can be used around them. Bacillus thuringiensis, a biological insecticide, shows very low toxicity to bees. A group of toxic insecticides must not be applied to blooming crops when bees are present. Diazinon, Imidan, malathion and Sevin are the high-risk materials.
3. Choice of Formulation: Different formulations vary in their toxicity to bees. Dust formulations are more hazardous than sprays, as they end up on bee hairs. Granular insecticides are less hazardous. Microencapsulated materials like Penncap-M are very dangerous around bees because the capsules have a tendency to adhere to bees because of size and electrostatic charge.
4. Residual Action: Residual activity is important when determining its safety to pollinators. An insecticide that degrades in a few hours is applicable with minimum risk when bees are not active.
5. Drift: Drift of sprays causes significant bee poisoning, especially when it reaches colonies or adjacent flowering weeds. Generally, you should not spray when the wind speed exceeds 10 mph.
6. Temperature: Temperature effects the bee-poisoning as well. If temperatures after treatment are low, insecticides remain toxic for much longer than in higher temperatures.
7. Distance from Treated Fields: The most damaged colonies are the closest to the treated fields. During the periods of pollen or nectar shortage however, hives within around five miles can be injured.
8. Time of Application: Evening application can greatly reduce any damage to the bees.
Steps to Reducing Damage:
Reducing these pesticide injuries to bees requires communication and cooperation between the beekeepers, farmers and applicators. The beekeepers must understand cropping practices and pest management practices that farmers use. The applicators should care for the locations of apiaries, obtain knowledge of honeybee behavior, and learn about materials and practices most hazardous to then.
It is highly unlikely that all poisoning can be avoided. However, a balance must exist between the effective use of insecticides, the preservation of pollinators, and the rights of all three parties, the beekeepers, farmers and applicators. Bee poisonings are avoidable in these cases:
1. Do not treat blooming fields. Special care is needed when spraying alfalfa, soybeans, and other legumes and pollinating crops.
2. Examine the fields and field margins before spraying, in order to determine bee activity on milkweeds, smartweed or dandelions. Eliminate weeds by mowing or tillage instead.
3. Choose short residual and low-hazard materials if you need insecticides during flowering to save the crop. Notify beekeepers as far in advance as you can.
4. Avoid spray drift by examining proximity to colonies.
5. Apply insecticides when the bees are not foraging. Apply the chemicals in the late evening or early morning.
6. Adjust spray programs to weather conditions. Choose the timing of application if low temperatures are expected, as residues can toxic to bees longer in cold weather. Also, avoid treating during hot evenings if you have beehives close to your field. Spray should never get in touch with the hives.
7. Read the label and follow the listed precautions.