# Sublethal Effects of Imidacloprid on Honey Bee Colony Growth and Activity at Three Si



## JWChesnut (Jul 31, 2013)

Newly published controlled study at multiple sites feeding honeybees neonics. Free full text download.
http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0168603&type=printable
Published: December 28, 2016
Sublethal Effects of Imidacloprid on Honey
Bee Colony Growth and Activity at Three Sites
in the U.S.
William G. Meikle1*, John J. Adamczyk2, Milagra Weiss1, Ales Gregorc3, Don R. Johnson4,
Scott D. Stewart5, Jon Zawislak6, Mark J. Carroll1, Gus M. Lorenz4
PLOS ONE | DOI:10.1371/journal.pone.0168603







Abstract
Imidacloprid is a neonicotinoid pesticide heavily used by the agricultural industry and shown
to have negative impacts on honey bees above certain concentrations. We evaluated the
effects of different imidacloprid concentrations in sugar syrup using cage and field studies,
and across different environments. Honey bee colonies fed sublethal concentrations of imidicloprid
(0, 5, 20 and 100 ppb) over 6 weeks in field trials at a desert site (Arizona), a site
near intensive agriculture (Arkansas) and a site with little nearby agriculture but abundant
natural forage (Mississippi) were monitored with respect to colony metrics, such as adult
bee and brood population sizes, as well as pesticide residues. Hive weight and internal hive
temperature were monitored continuously over two trials in Arizona. Colonies fed 100 ppb
imidacloprid in Arizona had significantly lower adult bee populations, brood surface areas
and average frame weights, and reduced temperature control, compared to colonies in one
or more of the other treatment groups, and consumption rates of those colonies were lower
compared to other colonies in Arizona and Arkansas, although no differences in capped
brood or average frame weight were observed among treatments in Arkansas. At the Mississippi
site, also rich in alternative forage, colonies fed 5 ppb imidacloprid had less capped
brood than control colonies, but contamination of control colonies was detected. In contrast,
significantly higher daily hive weight variability among colonies fed 5 ppb imidacloprid in Arizona
suggested greater foraging activity during a nectar flow post treatment, than any other
treatment group. Imidacloprid concentrations in stored honey corresponded well with the
respective syrup concentrations fed to the colonies and remained stable within the hive for
at least 7 months after the end of treatment.

http://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0168603&type=printable


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