A new study offers further evidence about the dangerous effects of pesticides on honey bees. Biologists at the University of California at San Diego have found that a commonly used crop pesticide makes honey bees picky eaters and also makes them reduce the number of waggle dances they perform. Waggle dances are how the bees communicate the location of a food source; bees exposed to the pesticide performed four to ten times fewer dances.
Indeed, as Daren Eiri, a graduate student and the first author of the study in the Journal of Experimental Biology, says, some bees simply stopped performing waggle dances altogether after exposure to pesticides.
The chemical in question is imidacloprid, which is a type of neonicotinoid — which has been linked to bees’ deaths. Imidacloprid has come under increasing scrutiny in the US and is banned for use in some crops in some parts of Europe. James Nieh, a professor of biology at UC San Diego who also authored the study, notes in Science Daily that, in 2006, imidacloprid was the sixth most commonly used pesticide in California. Besides being used in agriculture, it is also used in home gradens.
The scientists used different concentrations of sugar water to determine at what concentration bees would feed on it. They indeed found that bees exposed to imidacloprid were “less likely” to feed on law concentrations of sugar waters than those who had been exposed to such. Just a “small, single dose of imidacloprid” was enough to turn bees into “picky eaters,” who would only feed on “sweeter nectar and refused nectars of lower sweetness that they would normally feed on and that would have provided important sustenance for the colony,” notes Eri.
Beekeepers in the US and in Europe have lost about one-third of their managed bee colony every year due to colony collapse disorder, since 2006. Eri and the other researchers say they hope their research will have “implications for how pesticides are applied and used in bee-pollinated crops.”
How many more studies do we need to get the message out that imidacloprid is detrimental to bees?
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Photo by Ano Lobb. @healthyrx