For more than 10 years, honeybee colonies in the U.S. have been dying, and a new study confirms that some of the main reasons involve supposedly "bee-safe" pesticides found in fungicides, herbicides and insecticides.
Previous studies have analyzed the pesticides one at a time, and this led to inconclusive results. However, researchers from the University of Maryland have evaluated the effects of the entire phenomenon of pesticide exposures in bees.
The research investigated the effects of multiple substances bee colonies were exposed to, and the results indicated a correlation between colony deaths and exposure to different kinds of pesticides. Moreover, even fungicides, previously believed to protect the insects, were also involved in the death of the bee colonies.
The study, published on Sept. 15 in the journal Nature Scientific Reports, followed 91 colonies from three separate owners, during an entire agricultural season.
"Our results fly in the face of one of the basic tenets of toxicology: that the dose makes the poison," said Dennis vanEngelsdorp, a senior author of the study and an entomology assistant professor at UMD.
The researchers discovered that pesticide compounds were strictly correlated to colony death, because of the bee's incapacity to detoxify themselves from their effects. To better explain this phenomenon, the research paper uses a concept from cancer research — exposome.
Exposome is the total number of chemicals the human body is exposed to its entire life. However, the scientists did not analyze the exposome for each bee, but for the entire colony, which the study looked at as a superorganism functioning as a whole.
The most important death in the colony is the queen bee's, which endangers the entire superorganism, leading to its death, if the queen is not replaced. According to the research, the queen bees from colonies with very low pesticide contamination in the wax did not die, as opposed to all the other exposed ones that lost their queens over the beekeeping season.
"[N]ow many commercial beekeepers replace the queens in at least half of their colonies every spring in the hopes that this will prevent premature queen deaths," added Kirsten Traynor, lead author of the study.
The team could not correlate the deaths to neonicotinoid pesticide exposures, which is derived from nicotine and among the most popular pesticides worldwide.
The researchers hope that further attention will focus on discovering new patterns in the pesticides-honeybee relationship, starting from the insights of the current paper, to adapt to current industry practices.
Other studies have confirmed that bees get the highest concentration of pesticides from homes, because most of the time, the insects get pollen from plants and flowers in gardens exposed to these artificial substances.
Even though it was believed that using pesticides is, in fact, a way to insure the quality of the honey, as well as of the colony's life standards, the new study puts this theory under a new light.
