Insecticide increases effect of varroa mite February 4, 2016
Honeybees infected with the Varroa destructor mite have less stamina than those which have been effectively treated against the parasite. Additional exposure to the insecticide Imidacloprid further increases the harmful effect of the varroa mite. This was the conclusion of Wageningen UR scientists Lisa Blanken, Frank van Langevelde and Coby van Dooremalen as published in an article in the British Royal Society's magazine Proceedings B.
'Flight mill'
The scientists performed a unique experiment with various bee colonies. They captured worker bees returning to their colony with pollen at the hive opening and fitted a 'harness' to the top of their thorax. The bees were then attached to a smoothly running mill with a counterweight. "Imagine the bee version of a treadmill for horses," Van Dooremalen explains.
Combination of stressors
The bees flew circles in the mill while their flight speed and total distance were registered. Van Dooremalen: "This experiment showed that 'clean' bees – bees from colonies that had been treated against varroa – flew the fastest and farthest. Bees with a substantial varroa infection flew significantly shorter distances. Clean bees that were also given a realistic dose of Imidacloprid via sugar water in the colony flew as far and as fast as the control group. But when bees infected with varroa were given the same dose of Imidacloprid, they flew less far and for an even shorter time than bees that were only infected with varroa."
Read more at: http://phys.org/news/2016-02-insecticide-effect-varroa-mite.html#jCp
