Toxic metal selenium said a risk to honeybees critical to agriculture

RIVERSIDE, Calif., Oct. 3 (UPI) -- The pollutant metal selenium, which can accumulate in plants, can kill honeybees or delay their development, a study led by researchers in California found.

The anthropogenic pollutant joins other honeybee stressors including pesticides, pathogens and diseases, the researchers said.

"Metal pollutants like selenium contaminate soil, water, can be accumulated in plants, and can even be atmospherically deposited on the hive itself," lead study author Kristen Hladun, an entomologist at the University of California, Riverside, said. "Our study examined the toxic effects of selenium at multiple life stages of the honey bee in order to mimic the chronic exposure this insect may face when foraging in a contaminated area."

Honeybees, an important agricultural pollinator in the United States and throughout the world, may be at risk in areas of selenium contamination because of the biotransfer of the metal from selenium-accumulating plants, the researchers said.

Anthropogenic sources of selenium include mining and industrial activities such as petroleum refining and coal-power production, as well as where agricultural runoff is collected and can concentrate selenium from the surrounding soils, they said.

While low concentrations of selenium are beneficial to many animals, in higher concentrations it is toxic.

The toxic element can enter a honeybee's body through ingestion of contaminated pollen and nectar, the scientists said.

"It is not clear how selenium damages the insect's internal organs, or if the bee has the ability to detoxify these compounds at all," Hladun said. "Further research is necessary to examine the cellular and physiological effects of selenium."

In the United States, the known toxicity of selenium to wildlife and humans has resulted in the element being regulated by the Toxic Substances Control Act and the Clean Water Act.

The study has been published in the journal Environmental Toxicology and Chemistry.