06/12/2017
An interesting read!
High number of pesticides within colonies linked to honey bee deaths.
Honey bee colonies in the USA States have been dying at high rates for over a decade, and agricultural pesticides - including fungicides, herbicides and insecticides - are often implicated as major culprits. Until now, most scientific studies have looked at pesticides one at a time, rather than investigating the effects of multiple real-world pesticide exposures within a colony.
A new study by Bee World Editor Kirsten Traynor and colleagues from the University of Maryland, together with colleagues from the USDA and the universities of North Carolina and Penn State, is the first to systematically assess multiple pesticides that accumulate within bee colonies. The researchers found that the number of different pesticides within a colony - regardless of dose - closely correlates with colony death. The results also suggest that some fungicides, often regarded as safe for bees, correlate with high rates of colony deaths.
The researchers followed 91 honey bee colonies, 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. They also spent time in locations meant for honey production, as well as “holding areas” where beekeepers prepare large numbers of colonies for upcoming pollination contracts.
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. At every stop along the beekeepers’ itinerary, the researchers assessed three different parameters within each colony: the total number of pesticides; the total number of “relevant” pesticides (defined as those above a minimum threshold of toxicity); and each colony’s “hazard quotient,” a measure devised by other researchers to integrate the total hazard posed to each colony by the cumulative toxicity of all pesticides present.
“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,” said Kirsten Traynor. “These compounds have long been thought to be safe for bees. We’re seeing them at higher doses than the chemicals beekeepers apply directly to the colonies to control varroa mites. So that is particularly concerning.”
The paper, “In-hive pesticide exposome: assessing risks to migratory honey bees from in-hive pesticide contamination in the Eastern United States” by Kirsten Traynor, Jeffery Pettis, David Tarpy, Christopher Mullin, James Frazier, Maryann Frazier and Dennis vanEngelsdorp, can be found here: http://www.nature.com/articles/srep33207
