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Caption: A honey bee (Apis mellifera) is harnessed for study on a flight mill in biology professor James Nieh’s laboratory. Credit: UC San Diego

A common pesticide might be impairing seemingly healthy honey bee’s ability to fly.

Biologists from the University of California San Diego have demonstrated for the first time that Thiamethoxam, a neonicotinoid insecticide used on crops such as corn, soybeans and cotton, is damaging to honey bees.

The research revealed that long-term exposure to the pesticide over one to two days reduced the ability of the bees to fly, and short term exposure briefly increased their activity, where the bees flew farther but more erratically.

“Bees that fly more erratically for greater distances may decrease their probability of returning home,” James Nieh, a professor in UC San Diego’s Division of Biological Sciences, said in a statement. “The honey bee is a highly social organism, so the behavior of thousands of bees are essential for the survival of the colony.

“We’ve shown that a sub-lethal dose may lead to a lethal effect on the entire colony,” he added.

The researchers are now raising concerns about how pesticides could impact the insect’s capacity to pollinate and what its long-term impact on the health of honey bee colonies is.

The research team designed and constructed a bee flight-testing instrument from scratch, allowing them to fly bees under consistent and controlled conditions.

After testing and acquiring data for months, the researchers revealed that typical levels of neonicotinoid exposure resulted in substantial damage to the insect’s ability to fly.

“Our results provide the first demonstration that field-realistic exposure to this pesticide alone, in otherwise healthy colonies, can alter the ability of bees to fly, specifically impairing flight distance, duration and velocity” UC San Diego postdoctoral researcher Simone Tosi, said in a statement. “Honey bee survival depends on its ability to fly, because that’s the only way they can collect food.

“Their flight ability is also crucial to guarantee crop and wild plant pollination.”

Honey bees are an important species in nature because they provide essential ecosystem contributions such as the global pollination of crops and native plants. With populations declining, researchers are concerned about the impact on the environment, food security and human welfare.

The researchers found evidence of neonicotinoid insecticides in the nectar, pollen and water that honey bees collect.

“People are concerned about honey bees and their health being impaired because they are so closely tied to human diet and nutrition,” Nieh said. “Some of the most nutritious foods that we need to consume as humans are bee-pollinated.”

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