Agriculture News: Protecting bees, other pollinators important

By Keenan Bishop, Published:

If you attended Farm-City Field Day on July 10, and took the educational tour you heard local beekeeper James Hale discuss keeping bees. You also got to see his really cool observation hive.

Dr. Lee Townsend, UK entomologist, had a related article in the current Kentucky Pest News (kentuckypestnews.wordpress.com/) on protecting bees. As important as bees are to agriculture and since they are struggling to survive in some areas, I thought it would be good to go over some of his suggestions.

Pollinators, such as bees, wasps, butterflies, and flies, can be exposed to pesticides by being hit by spray droplets during an application, contacting spray residues on treated plants, and/or consuming a pesticide as nectar and pollen are collected.

Here are some ways to protect pollinators when pesticide applications are needed:

>Read the label carefully. Follow any specific requirements to protect pollinators.

>Avoid applying insecticides and fungicides to any plant in bloom.

>Be aware of your surroundings and weather conditions, especially wind speed and direction. Do not allow pesticide spray droplets to drift onto nearby flowering plants.

>Apply pesticides only after petals have fallen so flowers are less attractive to pollinators. If you must spray plants in bloom to save a crop, choose a pesticide/formulation with the lowest toxicity to bees and other pollinators. Organophosphate/carbamate, neonicotinoid, and pyrethroid insecticides have high residual toxicity to bees and other pollinators.

Pesticide formulations affect residual toxicity of an active ingredient. Dust (D), Wettable powder (WP), Liquid (L) or Flowable (F), Emulsifiable concentrate (EC).

Use the lowest labeled rate. For example, the extended residual toxicity to bees of a particular pyrethroid insecticide is one day at the highest use rate; at the low rate it is 4-6 hours.

>Avoid using any systemic insecticide on plants even after bloom if that product lasts until next season’s bloom period. Imidacloprid persists; dinotefuran is active only during the current season.

Carpenter bees

While on the subject of bees, let’s consider how to manage a pollinator that can be destructive — the carpenter bee. 

Earlier this summer carpenter bees were out in droves. Males, recognizable by the yellow spot on their face, hang out near nesting sites and may investigate intruders who enter “their” space. While intimidating, they do not have stingers.

Females use their strong mandibles to chew half-inch  diameter entry holes into soft, dry wood. Tunnels, ultimately, can be 6 to 10 inches long and can contain 6 or 7 individual larval cells. Over the years, galleries may become several feet long.

Carpenter bee control is not easy, so prevention is the best long-term strategy. Use of hardwoods when practical, or covering softwoods with flashing or screen will prevent damage to areas that are chronically attacked. Closing barn and shed doors while the bees are establishing new galleries should help to reduce infestations.

General maintenance helps because carpenter bees exploit rough areas on wood surfaces to begin a nest. Filling cracks and crevices and painting or varnishing exposed wood will make it less attractive.

There are some insecticide options, but accessibility and dimensions of infested surfaces can make treatment impractical or limit its success. The use of dust formulations of insecticides applied directly into tunnel openings has been the favored option. 

Insecticide sprays can be applied into tunnels, but pick-up of the dried residue may not be as rapid as with dusts. Insecticide applications to wood may provide some preventive effect, but bees are not ingesting the wood. 

After treatment, tunnel entries should be filled and sealed so they are not attractive to bees next season.

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