January 29, 2014

expert reaction to new paper on the impact of imidacloprid on bees

Neonicotinoid pesticides can impact bumble bees’ ability to collect food, even at low levels, of contamination, according to research published in the journal Ecotoxicology.

Dr Lynn Dicks, Natural Environment Research Council Research Fellow at the University of Cambridge, said:

“This is a very important study, because it provides further detail on how bumblebee foraging is made less efficient by exposure to imidacloprid at these levels.  Pollen foraging is key for the development of young bumblebees, because pollen is the main protein source in their diet.

“However, the important questions over what is a ‘field-realistic’ dose are not settled and they remain open.  This study was not designed to address that; rather, it was designed to provide a mechanistic explanation for the drop in queen production measured in a previous study by the same group (the famous Whitehorn et al study), and so it uses the same levels as that study (0.7 ppb in sugar water and 6 ppb in pollen).  These, particularly the pollen level, are at the upper end of what is found in the field, and likely to be higher than what bumblebee colonies (i.e. all the workers) are actually exposed to, because they don’t feed exclusively on oilseed rape.

“Average levels of another neonicotinoid, thiamethoxam, found in bumblebee-collected pollen by the Defra field study published last year were much lower than that (although not directly comparable, because it is a different chemical).”

‘Field realistic doses of pesticide imidacloprid reduce bumblebee pollen foraging efficiency’ by Hannah Feltham et al is published in Ecotoxicology