Study stirs controversy Bayer Crop Science denounces findings as ‘spectacularly incorrect’
Three scientific studies in the past two weeks have directly blamed insecticides for collapsing bee populations, providing fuel for activists and politicians who would like to restrict pesticide use.
In the most recent study, Harvard School of Public Health researchers found a “convincing” link between insecticides and colony collapse disorder (CCD), a term used to describe mysterious losses of 30 to 90 percent in commercial beekeeping operations.
In 2010, the Harvard scientists dosed hives with varying levels of imidacloprid, a Bayer Crop Science neonicotinoid insecticide registered for use on more than 140 crops in 120 countries. Six months later, 15 out of 16 hives dosed with the insecticide had died and the bees exposed to the highest levels of imidacloprid died first.
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The dead hives resembled the symptoms associated with CCD: empty except for food stores, pollen and young bees.
Based on that evidence, the study concluded that insecticides such as imidacloprid are a significant factor behind CCD. It is expected to be published in the Bulletin of Insectology in June.
Bayer Crop Science vigorously denounced the study April 5.
“Although the study claims to have established a link between imidacloprid and bee colony collapse, the symptoms observed in the study bees are not consistent with, or even remotely similar to, those of colony collapse disorder,” Bayer said in a news release.
“As such, the authors’ claims that their study explains the causes of CCD are spectacularly incorrect.”
Bayer also said the study’s authors ignored the consensus among entomologists that colony collapse is caused by multiple factors, including varroa mites, disease, inadequate nutrition and loss of genetic diversity.
The Harvard study, which was widely reported in the media, comes on the heels of bee and insecticide research published in March from studies in Britain and France.
The British study, published in Science, indicated that bumblebee colonies treated with imidacloprid produced 85 percent fewer queens than an untreated colony, thus limiting the colony’s ability to reproduce.
In the French study, researchers dosed honeybees with thiamethoxam, a seed treatment insecticide that Syngenta sells under the brand name Cruiser. The French scientists concluded the insecticide interfered with the bees’ homing instinct because bees treated with thiamethoxam were two to three times more likely to die away from the hive.
Aside from generating worldwide press, the European research also caught the attention of policy makers. France’s agriculture ministry has asked the country’s environmental agency to study the possibility of revoking Cruiser’s approval, according to Bloomberg.
A British MP, albeit from the Green Party, has asked the government to immediately ban neonicotinoids based on the Harvard results and the studies from Britain and France.
- Worker bees collect 30 kilograms of pollen per year, per hive. Bee pollen contains up to 35 percent protein, as well as various vitamins and minerals.
- There are several types, colours and flavours of honey, depending upon its nectar source, but all honey is a product of regurgitation.
- Bees secrete flakes of beeswax from four glands on the underside of their abdomens to build honeycombs. Scientists think honeycomb cells are hexagonal in shape because it requires the least material to create a lattice of cells within a given volume.
- Propolis, a sticky resin collected from trees by honeybees, is mixed with wax to make a sticky glue that the bees use to seal cracks and repair their hive.
- Royal jelly is a milky substance fed to a developing bee larvae to turn it into a queen bee. Royal jelly is made of digested pollen and honey or nectar, mixed with a chemical secreted from a gland in a nursing bee’s head. Each hive has only one queen, which can live for three to five years and can lay up to 2,000 eggs per day.
