In recent years honey bee colonies are being wiped out in the thousands across the globe and scientists are trying to pinpoint exact reasons why.
In a new study by researchers at University of Maryland in the US, scientists have revealed that honey bee colonies could be dying because of exposure to some fungicides, often regarded as safe for bees. Researchers note in their findings that dosage is what makes chemicals poison. They came across quite a few compounds and because of variety of these compounds, researchers note that the bees are getting overwhelmed and unable to detoxify themselves.
The researchers followed 91 honey bee colonies in the US, owned by three different migratory commercial beekeepers, for an entire agricultural season. The colonies began their journey in Florida and moved up the East Coast, providing pollination services for different crops along the way. A total of 93 different pesticide compounds found their way into the colonies over the course of the season, accumulating in the wax, in processed pollen known as bee bread and in the bodies of nurse bees.
The study, published online in the journal Scientific Reports, showed that colonies with very low pesticide contamination in the wax experienced no queen events or colony death, while all colonies with high pesticide contamination in the wax lost a queen during the beekeeping season.
The study results also suggest that some fungicides, which have led to the mortality of honey bee larvae in lab studies, could have toxic effects on colony survival in the field.
In the current study, pesticides with a particular mode of action also corresponded to higher colony mortality.
For example, the fungicides most closely linked to queen deaths and colony mortality disrupted sterols — compounds that are essential for fungal development and survival.
“We were surprised to find such an abundance of fungicides inside the hives, but it was even more surprising to find that fungicides are linked to imminent colony mortality,” lead author on the study Kirsten Traynor from the University of Maryland said. “These compounds have long been thought to be safe for bees,” Traynor noted.