Bees’ health damaged by common agricultural chemicals, researchers find
Previously, researchers did not believe fungicides had a negative effect since they’re not designed to kill insects.
The study, published this week in the journal PLOS ONE, is the first to analyze real-world conditions honey bees encounter while pollinating various types of crops.
Researchers from the University of Maryland and the U.S. Department of Agriculture collected pollen samples from hives in Delaware all the way to Maine. Samples were analyzed to determine the bees’ main pollen sources and what agricultural chemicals commingled with the pollen. To test their ability to resist Nosema ceranae – a parasite linked to colony collapse disorder – the researchers fed the collected pollen samples to healthy bees
Every sample contained sub-lethal levels of multiple agricultural chemicals, with an average of 9 different chemicals being present. One sample containing 21 different pesticides. Fungicide chlorothalonil, a pesticide commony used on apples, and fluvalinate, an insecticide used by beekeepers to control mites, were present most frequently.
Surprisingly, the study found that bees fed pollen samples containing chlorothonatil were almost three times as likely to be infected by Nosema, than bees not exposed to the fungicide. The insecticide used to control mites also impaired the bees’ ability to withstand nfection.
Beekeepers are aware of the risks involved in using miticides, as the chemicals compromise a bee’s immune system. But the damage is less than if mites were left unchecked. However, the discovery that common fungicides are harmful at real world dosages is new information, pointing to gaps in existing regulations.
Previously, researchers did not believe fungicides had a negative effect since they’re not designed to kill insects. At present, federal regulations restrict the use of insecticides while pollinating insects are foraging, but there are no such restrictions on fungicides. In light of this new information, researchers suggest this policy be reconsidered.
Unexpectedly, most of the crops being pollinated did not appear to provide their hives with much nourishment. When the team collected samples from bees foraging native North American crops, like blueberries and watermelon, they discovered the pollen came from other flowering plants in the area. This suggests that honey bees, which evolved in the Old World, are less efficient at collecting pollen from New World crops.
Though not directly related to colony collapse disorder, a phenomenon which remains unexplained, the results of the study helped to shed some light on the many factors involved in stressing honey bee populations.