According to the research, neonicotinoids damage bumblebees’ brain cells and subsequently result in colony growth deficits. Although this doesn’t prove that these chemicals are solely to blame for the worldwide decline in bees, the researchers say that the work demonstrates beyond doubt that their consumption causes brain dysfunction and poor colony performance.
As the study points out, I don’t believe these pesticides are alone in harming the honey bee populations, but they are a cause that no longer can be ignored. I believe that certain beekeeper practices, bee pests and diseases are the cause of CCD along with neonicotinoids. But just because these chemicals are not the sole cause of CCD and other honey bee issues does not mean they should be ignored. I applaud the province of Ontario’s move to limit their use and the petitions currently circulating to monitor them more closely and further limit their use.
Neonicotinoids are systemic pesticides, meaning that they are taken up by the plant and transported to all its tissues, including the pollen and nectar. They work by causing excessive excitation of nerves, eventually leading to paralysis and death. Unfortunately, bees have a genetic vulnerability to these pesticides and are less able to detoxify them than many other insects.
The amount of neonicotinoid that ends up in the nectar and pollen consumed by bees is around 2.5 parts per billion (ppb). Although it’s known that bees are susceptible to these chemicals, there has been a lot of debate over whether this amount is enough to harm them. To find out more, UK researchers fed bumblebees several different neonicotinoids at this level and investigated the effect on their brains.
As described in The FASEB Journal, they found that some neonicotinoids rapidly shut down the energy-making factories in the bees’ brain cells, the mitochondria. At even lower than 2.5 ppb, the brain cells became overly sensitive to a normally innocuous level of one of the main neurotransmitters in the nervous system. This causes brain cells to begin to malfunction, which can affect the bee’s ability to learn and form important memories, such as their route home.