Chapter 8 Ecotoxicity of Neonicotinoid Insecticides to Bees
Axel Decourtye and James Devillers

This chapter has revealed new insights into behavioral effects of neonicotinoids including effects
on mobility, orientation, foraging and learning. The lowest observed effect concentrations for
imidacloprid reported were the following: 3 g kg1 for foraging activity and 12 g kg1 for
olfactory learning.

It is not clear whether the endpoints tested in these sublethal studies can be clearly related
to the respective field effect of concern. Conversely, for the methods based on orientation
and homing ability and that were proposed to be tested on bees, the ecological relevance is
better. If measurable differences in homing flight are found in such experimental design, an
individual, exposed under field conditions would probably suffer from this effect. 

Foragers fed with imidacloprid-added syrup at the concentration of 100 g kg1 showed a delay
for returning to their hive. Such acute exposure cannot probably occur in the realistic conditions
since the concentrations of imidacloprid and its metabolites, to which honey bees are exposed
always have been measured lower than 10 g kg1. Although data in field tests are
often inadequate to demonstrate causation unambiguously, the loss of the colonies could not
be verified for imidacloprid under field conditions, where no effects on hive development have
been detected.


Insect Nicotinic Acetylcholine Receptors, edited by Steeve Hervé Thany.
©2010 Landes Bioscience and Springer Science+Business Media.

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