Protecting Pollinators from Pesticides

excerpted from the UGA Honey Bee Program Website

The Affect of Pesticides on Bees

Pesticides are substances used to eliminate unwanted pests. Insecticides rid us of unwanted insects. Unfortunately, honey bees are insects and are greatly affected by insecticides.

There are several ways honey bees can be killed by insecticides. One is direct contact of the insecticide on the bee while it is foraging in the field. The bee immediately dies and does not return to the hive. In this case the queen, brood and nurse bees are not contaminated and the colony survives. The second more deadly way is when the bee comes in contact with an insecticide and transports it back to the colony, either as contaminated pollen or nectar or on its body.

Preventing Pesticide Kills

Apply pesticides in the evening

Many pesticides are extremely toxic to honey bees and other beneficial insects. Honey bees are attracted to blooming flowers of all types. If at all possible do not spray blooms directly with pesticides. If the bloom needs to be sprayed, apply the pesticides in the evening hours. Honey bees forage during daylight hours when the temperatures are above 55-60°F. As the sun begins to set, they return to their hives for the evening. Thus, spraying pesticides in the evening hours can greatly reduce honey bee mortality because the bees are not in the fields.

Choose the appropriate formulation

The appropriate choice of formulation is another way to avoid honey bee pesticide kills. Pesticides come in different formulations: dusts (D), wettable powders (WP), soluble powders (SP), emulsifiable concentrates (EC), solutions (LS), and granulars (G). Solutions, emulsifiable concentrates, and granulars are the best formulations to use. Solutions and emulsifiable concentrates dry quickly and do not leave a powdery residue unlike the dusts and wettable powders. Granulars are similar to dusts but are larger in particle size. They are applied into the soil or broadcast on the surface of the ground. They are seldom used on blooming plants and are essentially non-hazardous to bees. On the other hand, dusts and wettable powders will adhere to the thousands of tiny hairs found on the body surface of the honey bee. These dust particles are then transferred back to the hive and stored along with the pollen. This can cause an entire colony to collapse if the pollen is fed to the queen or the brood.

Use less toxic, rapidly degradable pesticides

Using less toxic pesticides that degrade rapidly is also important in reducing honey bee mortality (See Table of Insecticides and Miticides for pesticide toxicity and residual time). Many of the newer pesticides being marketed today have a faster residual time which is the time required to reduce the activity of the chemical to safer levels for bee activity. When these pesticides are sprayed in the fields, it takes only a few hours for them to degrade as opposed to a few days or weeks.

Alter application method

The method of application can also change the risk of pesticide poisoning. Aerial applications have the highest potential risk for causing bee kills. Most bee kills occur when the pesticide drifts or moves from the target area into the apiary or onto crops attractive to the bees. The outcome of drift can be catastrophic. Spraying during windy days greatly increases the risk of drift. Using granular formulations, soil treatments or equipment that confines the spray to the intended target can help reduce the risk of drift from pesticides.

More Information + More Ways to Help Pollinators

National Geographic: 9 Ways You Can Help Bees and Other Pollinators At Home

Center for Pollinator Research: What steps can I take to help the bees and other pollinators?

USDA Natural Resources Conservation Service: How Gardeners Can Help Pollinators

National Wildlife Federation: 10 Ways to Save Pollinators