Scientists continue to study the decline of bees and the phenomenon known as colony collapse. Recently, a few more pieces of the puzzle have begun to fit together. NPR reports on two field studies that shed light on just how pesticides called neonicotinoids are affecting bee populations.
The first study, conducted at 33 sites in the EU, tracked bee populations placed near fields of canola. Some of the fields had been treated with neonicotinoids as seeds, and others were treated with a combination of neonicotinoids and fungicides, or fungicides alone. In general, the scientists found that exposure to neonicotinoids caused problems for both wild bees and honeybee colonies, from decreased reproduction to colonies failing to survive the winter. However, bees studied in Germany thrived, with or without neonicotinoids. These bees could find a wider variety of flowers to feed on, so that the neonicotinoid-treated plants were a smaller percentage of their intake, and they were also comparatively free of parasites, leading the team to conclude that variety of food sources, local environment, and general health of the bee population all play into the effect of neonicotinoids.
The second study, from Canada, compared bee colonies closer to neonicotinoid sources to those farther away. This team found some troubling evidence regarding the use of these pesticides. First, they found that the pesticide was measurable in the harvested pollen for months, even though neonicotinoids are used only on seeds. Next, they found that most of the contaminated pollen came from untreated wild plants, not industrial crops. The scientists concluded that some neonicotinoids get into the groundwater, and then taken up by untreated plants. When the pesticide exposure was replicated in the lab, the team found that exposed bees don’t keep their hives as clean and tend to lose their queens more often, which usually results in the death of the colony.
Both these studies, taken together, are helping scientists form a better picture of how we can protect the bees that are so crucial to our food supply. As more research is done, the puzzle pieces begin to fit together.