Beehive Buzz: Honey Bees and Glyphosate

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A diagram of a glyphosate molecule. Image: Chemical & Engineering News




Bee advisory box.

The EPA Bee Advisory Box. Image: US Environmental Protection Agency.

Eric asked for information about a new colony of bees, “I was given a swarm someone caught and moved them to where my cousin is planting a garden today. He said something about eventually using Roundup®. Is there anything I should do to protect my bees for when he does spray?”

To answer Eric’s question, AHA wants to share a story of an experienced beekeeper. This beekeeper was the President of the Louisiana Beekeepers Association (LBA, www.labeekeepers.org), and he talked about placing his hives next to a soybean field. The entrances of half of the hives faced the field, and the other half faced away from the field. The farmer sprayed insecticide on the field, and the hives facing the field suffered damage while the hive facing away from the field survived easily. The take-home message is to face your hives to minimize exposure to insecticides.

However, Roundup® is an herbicide meant to treat weeds. The active ingredient in this product is called glyphosate, and it prevents the development of a protein that only plants can produce. There would be no acute lethal effects on insects.

Yet, a scientific study published in January 2023, “Effects of spinetoram and glyphosate on physiological biomarkers and gut microbes in Bombus terrestris,” made this report on the sublethal effects on bees, “However, recent studies have found that honeybee exposure to glyphosate has non-target sublethal effects on reproductive capacity, immunity, and cognitive ability in honeybees (Chmiel et al., 2020; Odemer et al., 2020). Moreover, Weidenmuller et al. (2022) found that consistent glyphosate exposure impairs the thermoregulatory capacity of bumblebees.”

Bee Culture, a professional beekeeping magazine, reported a different conclusion in its article, “IT’S NOT THE GLYPHOSATE, IT IS THE INERT INGREDIENTS,” citing the researchers who published their findings…in the Journal of Applied Ecology. This study found, “the researchers said they used a few versions of Roundup, the brand-name herbicide made by Bayer AG, and found mortality rates of greater than 90% in bumblebees exposed to it. But a glyphosate-free version also killed 96% of exposed bees, they said, ‘demonstrating that the active ingredient, glyphosate, is not the cause of the mortality.’

Surfactants and other ingredients may suffocate the bees by blocking their tracheal systems, according to the study.

Researchers have already established that surfactants are toxic to honeybees and solitary bees. This was the first major study finding similar threats to bumblebees, the researchers said.”

To protect honeybees and other pollinators from pesticide exposure, applicators need to read the “Bee Advisory Box” on pesticide labels on how to apply pesticides safely with respect to pollinators.

If you want to contact “Beehive Buzz,” please send your questions and pictures to Keith Hawkins, Area Horticulture Agent (AHA), 318.264.2448 or khawkins@agcenter.lsu.edu . Also, you can be on the “beemail” email list by emailing your request to the address above.

“This work has been supported, in part, by the USDA National Institute of Food and Agriculture, Renewable Resources Extension Act Award, Accession Number 1011417.”

“Mention of trade names or commercial products and services in this article is for informational purposes only and does not constitute endorsement by Louisiana State University AgCenter.”

6/20/2023 3:12:23 PM
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