Pesticide Cocktail: Mixed Farming Chemicals Are Killing More and More Bees

According to a review of 90 research, agricultural pesticides provided to farmers ready-mixed into "cocktails" can kill twice as many bees.

Each study looked at the effects of environmental factors, including pesticides and inadequate diet.

Researchers utilized this information to calculate how the pollinating insects were affected by a mixture of these stressors.

Reasons Why Bees Are Dying At An Alarming Rate — Shutterstock

Licensed Regulations

They also believe that commercial formulations containing several substances should now be required to have their own licenses.

"Exposure to numerous pesticides is the rule, not the exception," said the study's lead author, Dr. Harry Siviter of the University of Texas at Austin, on BBC Radio 4's Inside Science program.

Pesticide Levels and Flourishing Colonies

A 2016 study found that bee colonies with higher pesticide levels were significantly more likely to perish.

"If you had a honeybee colony exposed to one pesticide that kills 10% of the bees and another pesticide that kills another 10% of the bees, you would anticipate 20% of the bees to be killed if the effects were cumulative," Dr. Siviter explained.

However, a "synergistic impact" might result in 30-40% mortality.

"And when we looked at the interactions, that's precisely what we discovered," he added.

Dr. Siviter added that while licensing commercial formulations for usage, "we definitely need to examine the interplay between those substances."

"Because we don't keep track of pesticides after they're approved for use, we're proposing post-licensing observations."

"If those pesticides [when applied together] cause harm to bees, that impact is documented."

Adaptation and Tolerance Development

Queen Bee Produces Own Sperm, So There's No Need for 'King Bee' — Worker bees surround a queen, who is marked with a yellow spot on her back, in the colony of beekeper Reiner Gabriel in the garden of his home near Berlin on April 25, 2013 in Blankenfelde, Germany. Local beekeepers claim their yearly loss rates within their bee populations has gone from an average of 10% per year to 30% per year over the last 10 years, though they are unsure whether the cause lies with a mite and a virus it might be spreading or with the increased use of certain pesticides by local farmers. According to a recent report prepared by Greenpeace seven pesticides currently in use in Europe present a real danger to bees. Bees are essential in nature in pollenating a wide variety of plants and trees. Photo by Sean Gallup/Getty Images

However, according to new research released this week, bees worldwide are gaining the capacity to "clean out" a particularly harmful parasite known as varroa. This mite lives and feeds on honeybees and larvae.

Bees already have complex sanitary behaviors in place, such as removing diseased larval broods from the hive.

And now, data from 40 years of research on colonies that survive infestations without chemical treatment has been published in the Royal Society journal Proceedings B, revealing that they are evolving to "repurpose" their behavior against varroa.

"We see this resistance grow throughout the world," the University of Salford's Isobel Grindrod said.

"We also see an increase in beekeepers not needing to use chemical treatments to cure [the mites] recently."

She said that "pressure" from the mites was forcing healthy bees to adjust.

Resilient Busy Bees

"Their flexibility is critical, and that's why we need to sustain healthy bee colonies - to maintain that adaptability - because new illnesses and pressures will emerge in the future."

On BBC Inside Science on Radio 4 and BBC Sounds, interested people can learn more about bees' fights with parasites and chemicals.

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Tags Bees , Pollution , Pesticides