This past weekend, I looked at a colony of honey bees that had died; a large pile of dead bees were spread in front of the entrance with more dead bees on the bottom board. The dead bees had their proboscises extended, which is common with pesticide poisoning. This hive was very strong and active the week before. It is always a tragedy to lose a colony of pollinators, particularly if due to pesticide poisoning.
Pollinator protection has become a common phrase that we often hear. Those of us working in agriculture recognize honey bees and other pollinators are as much a part of agriculture as cattle and corn. Prior to 2006, overwintering colony losses occurred at the rate of about 15% annually; since that time, losses have been closer to 40% each year. Losses at this level are unacceptable and unsustainable.
There are a variety of causes that contribute to these losses, which include parasitic mites, diseases, starvation, queen failure, poor management, and, yes, pesticide poisoning. However, pesticides are under our direct control, and we can take steps to minimize their effects on pollinators.
Figure 1. Native pollinators like this bumble bee at a tomato flower are just as important to agriculture as honey bees (Photo: Ric Bessin, UK)
Figure 2. Pesticide contamination of blooming weeds or ornamental plants is just as hazardous as that of flowering crops.(Photo: Ric Bessin, UK)
Avoid Contaminating Plants in Bloom
The risk of harming insect pollinators is low when applications are made to fields or gardens with no flowering plants, even when materials that are highly toxic to pollinators are used. However, when any pesticide application is made to plants in bloom, crops or weeds, the risk to pollinators needs to be considered. This is a situation in which applicators need to find materials that are not toxic to pollinators or to find ways to apply toxic products so that pollinators are not exposed.
Many insecticide labels prohibit spraying areas in which pollinators are actively foraging. This is subtle language as it does not say to not spray blooming plants. There are times when plants may be in bloom and pollinators are not actively foraging, such as cool mornings (temperature below 50oF) or late evenings when the sun is beginning to go down. Labels also do not say ‘blooming crops’, as pollinators do care if it is a flower on a weed or crop plant. Spraying flowering weeds can be just as hazardous to pollinators as spraying crops in bloom.
Some labels will require that the pesticide applicator notify beekeepers 48 hours in advance when applying these products to any plant in bloom. The KDA has an on-line, anonymous program that applicators can use to notify beekeepers within five miles of fields to be treated (Pollinator Protection Program).
Avoid Pesticide Drift onto Colonies
Where there has been direct evidence of pesticide kills of honey bee colonies, pesticide drift over the colonies is frequently the case. To avoid pesticide drift onto honey bee colonies, the first step is to know where the colonies are around fields that will be treated. Get to know your local beekeepers and where they keep their colonies. Work with them to select locations for colonies where they will be set back from areas that will be treated. Having a vegetation buffer strip of trees will help to prevent drift onto the colonies. Don’t spray when the conditions favor drift, especially in the direction of managed colonies.
Avoid Contaminating Water Sources for Pollinators
Pollinators collect more than just nectar and honey. If you have ever had a teaspoon of honey, you will know that the next thing you need is a drink of water. It is the same with honey bees. Beekeepers put out watering stations for honey bees, and just like the colonies themselves, pesticide drift over these areas would result in contamination. It is best to locate watering stations in areas protected from pesticide drift, as with the colonies.
A Final Comment
Managing pesticides to avoid impacting pollinators is required to stay consistent with pesticide labeling. Most insecticide labels have pollinator protection requirements.
By Ric Bessin, Entomology Extension Specialist
Kentucky Pest News 