13 March 2012 - corrected PROOF Bulletin of Insectology 65 (1): xxx-xxx,
2012
ISSN 1721-8861
March 13, 2012 - Bulletin of Insectology corrected proof 1
In situ replication of honey bee colony collapse disorder
Chensheng LU1, Kenneth M. WARCHOL2, Richard A. CALLAHAN3
1Department of Environmental Health, Harvard School of Public Health,
Landmark Center West, Boston, MA, USA
2Worcester County Beekeepers Association, Northbridge, MA, USA
3Worcester County Beekeepers Association, Holden, MA, USA
Abstract
The concern of persistent loss of honey bee (Apis mellifera L.) colonies
worldwide since 2006, a phenomenon referred to as colony
collapse disorder (CCD), has led us to investigate the role of imidacloprid,
one of the neonicotinoid insecticides, in the emergence
of CCD. CCD is commonly characterized by the sudden disappearance of honey
bees (specifically worker bees) from hives
containing adequate food and various stages of brood in abandoned colonies
that are not occupied by honey bees from other colonies.
This in situ study was designed to replicate CCD based on a plausible
mechanistic hypothesis in which the occurrence of
CCD since 2006 was resulted from the presence of imidacloprid, one of the
neonicotinoid insecticides, in high-fructose corn syrup
(HFCS), fed to honey bees as an alternative to sucrose-based food. We used a
replicated split-plot design consisting of 4 independent
apiary sites. Each apiary consisted of 4 different imidacloprid-treated
hives and a control hive. The dosages used in this
study were determined to reflect imidacloprid residue levels reported in the
environment previously. All hives had no diseases of
symptoms of parasitism during the 13-week dosing regime, and were alive 12
weeks afterward. However, 15 of 16 imidaclopridtreated
hives (94%) were dead across 4 apiaries 23 weeks post imidacloprid dosing.
Dead hives were remarkably empty except for
stores of food and some pollen left, a resemblance of CCD. Data from this in
situ study provide convincing evidence that exposure
to sub-lethal levels of imidacloprid in HFCS causes honey bees to exhibit
symptoms consistent to CCD 23 weeks post imidacloprid
dosing. The survival of the control hives managed alongside with the
pesticide-treated hives unequivocally augments this
conclusion. The observed delayed mortality in honey bees caused by
imidacloprid in HFCS is a novel and plausible mechanism
for CCD, and should be validated in future studies.
Key words: colony collapse disorder, imidacloprid, Apis mellifera,
neonicotinoid insecticides, high-fructose corn syrup.
Kind regards,
Ghislain De Roeck
50°45414" N
3°54'48"E
Belgium
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