Some Washington State beekeepers have expressed concern to state agricultural agencies regarding the impact of off-the-shelf neonicotinoid insecticides to honey bees in urban areas. To examine potential neonicotinoid honey bee colony exposure from pollen foraging, a comparative assessment of apiaries in urban, rural and agricultural areas was undertaken in the fall of 2013 in incorporated and non-incorporated areas of Thurston, Clallam, Pierce, and King Counties.
 
In spring and summer 2014, the bee hive apiary program was extended and included locations in Clark, Lewis, Island, Snohomish, Jefferson, Skagit, Grant, and Spokane Counties. Apiaries ranged in size from one to hundreds of honey bee colonies, and included those operated by commercial, sideline (semi-commercial), and hobbyist beekeepers. This study specifically evaluated residues in/on wax and bee bread (stored pollen in the hive) for the nitroguanidine-substituted neonicotinoid insecticides imidacloprid and its olefin metabolite, together with the active ingredients clothianidin, thiamethoxam, and dinotefuran.
 
Conclusion/Findings
·         Over a one-year period, neonicotinoid residues were detected in less than 5% of the apiaries located in rural and urban landscapes in Washington State.
·         About 50% of beebread samples collected from apiaries in agricultural landscapes contained the insecticides clothianidin and thiamethoxam. However, most of the residues detected at concentrations above the method LOD were below the LOQ. A probabilistic risk characterization using the distribution of residues and an array of NOAECs for sublethal individual bee and colony level toxicity indicates a low likelihood of adverse effects.
·         Presenting the combined neonicotinoid beebread residue data in the form of total imidacloprid equivalent residues and probabilistic risk quotients provides a mechanism to more effectively communicate to beekeepers and municipalities the validity of restrictive ordinances in areas with little or no risk from exposure to foraging honey bees
·         The combined data from 1,490 separate neonicotinoid residue evaluations gathered in the fall of 2013 and spring/summer of 2014 at 149 hive locations indicate ca. 97% matrix samples with no detectable residues.
·         Of the wax and bee bread residues detected, all were less than 5 ppb.

Survey and Risk Assessment of Apis mellifera (Hymenoptera: Apidae) Exposure to Neonicotinoid Pesticides in Urban, Rural, and Agricultural Settings
T. J. Lawrence, E. M. Culbert, A. S. Felsot, V. R. Hebert, and W. S. Sheppard
Journal of Economic Entomology Advance Access published January 19, 2016

             ***********************************************
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