Pesticides can affect generations of bees

A recently released study by researchers at the University of California Davis revealed that pesticides can have lasting effects on bee health, reducing their reproduction rate.

According to the findings, published in the Proceedings of the National Academy of Sciences, multiple generations of bees may be needed to recover from one pesticide application.

Here’s a rundown of the study.

• WHAT ARE THE STUDY’S CONCLUSIONS? It was conducted by exposing blue orchard bees to imidacloprid, a common insect-control chemical, with the label’s recommended amount. The bees were given one application for two years, which is a standard level of exposure, according to the UC Davis article.

“Repeated exposure across two years had an additive negative effect on individual reproduction, which led to a really dramatic reduction in population growth,” said Clara Stuligross, the study’s lead author.

Researchers concluded that bees that came into contact with insecticides as larvae and, as adults, produced 44 percent fewer offspring. And bees that were exposed to the chemical two years straight had a 72 percent reduced population growth rate, compared to bees that did not have any level of exposure.

• THE STUDY LOOKED AT ONLY ONE PESTICIDE. The research was based on the use of imidacloprid, an insecticide that mimics nicotine, which is toxic to insects.

Stuligross, a UC Davis Ph.D candidate in ecology, said that because there is a large variety of insecticides on the market, you can’t extrapolate the study’s results. But she thinks the effects of imidacloprid on bees will be reflective across similar types of pesticides.

“It also helps us understand, generally, the effects of multiple exposures to pesticides,” she said.

• THE IMPORTANCE OF BEES: According to the Planet Bee Foundation, an environmental education nonprofit based in San Francisco, bees are the most efficient pollinators in the world. These buzzing insects help plants survive, which, in turn, provides for our food supply, wildlife and environment.

“They’re really important for our ecosystem,” Stuligross said. “And so understanding how this pesticide exposure affects bees over time is important for understanding how to actually support them and how to continue supporting our healthy and sustainable food systems.”