You might not think that insects are a big part of the food industry, but they are. Bees, in particular, can impact the pollination of crops that range from strawberries to cucumbers to apples. Now, though, scientists have discovered that bees may be at greater risk than previously thought. It turns out that four pesticides used on crops to kill insects and fungi also kill honeybee larvae within their hives.
In previous research, scientists found that forager bees bring back an average of six different pesticides to their hives on the pollen they collect. Nurse bees then use this pollen to make beebread, which they then feed to larvae.
In order to better assess the effects of these common pesticides, the researchers reared larvae in their lab. They then applied four common pesticides--fluvalinate, coumaphos, chlorothalonil and chlorpyrifos--alone and in combination to honeybee larvae.
"We found that four of the pesticides most commonly found in beehives kill bee larvae," said Jim Frazier, one of the researchers, in a news release. "We also found that the negative effects of these pesticides are sometimes greater when the pesticides occur in combinations within the hive. Since pesticide safety is judged almost entirely on adult honeybee sensitivity to individual pesticides and also does not consider mixtures of pesticides, the risk assessment process that the Environmental Protection Agency uses should be changed."
It's likely that the pesticides either directly poison honeybee larvae or indirectly kill them by disrupting the beneficial fungi that are essential for nurse bees to process pollen into beebread. Whichever the case, the pesticides are deadly to the larvae, which can impact the health of honeybee colonies--and impact food sources.
That's not all, either. These chemicals could also be impacting humans. The researchers were quick to note that pesticides in the food supply could drastically affect people.
"There is a growing body of research that has reported a wide range of adverse effects of inactive ingredients to human help, including enhancing pesticide toxicities across the nervous, cardiovascular and hormone systems," said Chris Mullin, one of the researchers, in a news release. "The bulk of synthetic organic chemicals used and released into U.S. environments are formulation ingredients like NMP, which are generally recognized as safe. They have no mandated limits on their use and their residues remain unmonitored."
The findings are published in the journal PLOS One.
