The long-term risk to honey bee colonies in the field was investigated, including the
sensitive overwintering stage, from four years consecutive single treatment crop exposures to flowering maize and oilseed
rape grown from thiamethoxam treated seeds at rates recommended for insect control. Throughout the study, mortality,
foraging behavior, colony strength, colony weight, brood development and food storage levels were similar between
treatment and control colonies. 

Detailed examination of brood development throughout the year demonstrated that
colonies exposed to the treated crop were able to successfully overwinter and had a similar health status to the control
colonies in the following spring. We conclude that these data demonstrate there is a low risk to honey bees from systemic
residues in nectar and pollen following the use of thiamethoxam as a seed treatment on oilseed rape and maize.

Residues in the hive were even lower in both the maize and oilseed rape trials, being at or below
the level of detection of 1 mg/kg for bee bread in the hive and at or below the level of detection of 0.5 mg/kg for hive nectar, honey and royal jelly samples.

Pilling E, Campbell P, Coulson M, Ruddle N, Tornier I (2013) A Four-Year Field Program Investigating Long-Term Effects of Repeated Exposure of Honey Bee Colonies to Flowering Crops Treated with Thiamethoxam. PLoS ONE 8(10)

Editor: Dennis vanEngelsdorp, University of Maryland, United States of America

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