This is a brief review of a scientific paper published in 2017:
Tosi, Simone & Burgio, Giovanni & Nieh, James. (2017).
Scientific Reports. 7. 1201. 10.1038/s41598-017-01361-8.
"Pesticides can pose environmental risks, and a common neonicotinoid pesticide, thiamethoxam, decreases homing success in honey bees.
Neonicotinoids can alter bee navigation, but we present the first evidence that neonicotinoid exposure alone can impair the physical ability of bees to fly.
We tested the effects of acute or chronic exposure to thiamethoxam on the flight ability of foragers in flight mills.
Within 1 hr of consuming a single sublethal dose (1.34 ng/bee), foragers showed excitation and significantly increased flight duration (+78%) and distance (+72%).
Chronic exposure significantly decreased flight duration (−54%), distance (−56%), and average velocity (−7%) after either one or two days of continuous exposure that resulted in bees ingesting field-relevant thiamethoxam doses of 1.96–2.90 ng/bee/day.
These results provide the first demonstration that acute or chronic exposure to a neonicotinoid alone can significantly alter bee flight.
Such exposure may impair foraging and homing, which are vital to normal colony function and ecosystem services."
As discussed elsewhere on this website, neonicotinoid
pesticides are very widely used across the global, and on a very broad range of
They are known to persist in the environment after their use.
For the purposes of reviewing the above study, it is also important to remember that after use, neonicotinoids can be found:
Thus, bees visiting and feeding on such plants will be routinely exposed to neonicotinoid pesticides.
The authors of the above paper also note that other studies have shown:
Some of the studies examining the effect of neonicotinoid pesticides have been carried out using bee colonies known to have measurable levels of Varroa and it appears that the effect of the neonicotinoids used in these studies may be a synergistic one between neonicotinoid and Varroa, which leads to impaired flight distance in the bees.
It has also been previously shown that ‘second generation’ neonicotinoid (thiamethoxam = TMX) reduces ‘forager return’ rates to the nest (i.e. in bee colonies that consume TMX, there is an increase in the number of bees that fail to return to the nest from foraging trips), suggesting that TMX impairs navigation or flight ability or both.
The bee colonies used in this study did not have any
measurable levels of Varroa, so the
study demonstrates a direct effect of the study compound (thiamethoxam - TMX),
rather than merely a synergistic effect between neonicotinoid and Varroa.
study demonstrates that TMX alone impairs the physical ability of bees to fly.
The authors of this study state that a sub-lethal dose or chronic neonicotinoid exposure is sufficient to significantly alter honey bee flight ability. This alteration may impair foraging and homing in affected bees – thereby creating a negative impact on colony function.