Figure 2. AChE relative quantity in bumble bee heads as a function of days since the beginning of corn planting.

Open circles and dotted line refer to control bumble bees’ AChE levels whereas filled circles and continuous line are for exposed bumble bee samples. Day 0 corresponds to the first day of corn planting and bumble bee colonies were placed in the field at this date. First samples were collected at Day 7 to ensure bumble bees had gotten acquainted with their new environment. In 2012, last bumble bee samples were collected at Day 35, and in 2013, at Day 24, when corn planting had been completed.