Source: Journal of Economic Entomology
Vol. 102, No. 2, April 2009, Page 616 - 623

Does Imidacloprid Seed-Treated Maize Have an 
Impact on Honey Bee Mortality?

ABSTRACT
Beekeepers suspected maize, Zea mays L., treated with 
imidacloprid to result in substantial loss of honey bee 
(Hymenoptera: Apidae) colonies in Belgium. The objective 
of this study was to investigate the potential impact of 
maize grown from imidacloprid-treated seeds on honey
bee mortality. A survey of 16 apiaries was carried out,
and all maize fields treated or not with imidacloprid 
were located within a radius of 3,000 m around the
observed apiaries. Samples of honey, beeswax, and 
bees were collected in three colonies per apiary and
analyzed for pesticide contain by liquid chromatography-
tandem mass spectrometry and gas chromatography-tandem 
mass spectrometry. We first found a significant correlation 
between the number of colonies per apiary and the mortality 
rates in an apiary. In addition, this mortality rate was 
inversely correlated with the surface of maize fields 
treated and not with imidacloprid, suggesting that this
pesticide do not interact with bees' fitness. Moreover,
a very large number of our samples contained acaricides
either prohibited or ineffective against Varroa destructor 
(Anderson & Trueman) (Acari: Varroidae), suggesting that
the treatment methods used by the beekeepers to be 
inadequate for mite control. Our results support the 
hypothesis that imidacloprid seed-treated maize has 
no negative impact on honey bees.

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