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. *********************************************** The BEE-L mailing list is powered by L-Soft's renowned LISTSERV(R) list management software. For more information, go to: http://www.lsoft.com/LISTSERV-powered.html Guidelines for posting to BEE-L can be found at: http://honeybeeworld.com/bee-l/guidelines.htm