Location of the colonies at the trial plots

One can possibly increase exposure by placing the colonies on the edge of the field. Studies have shown that pesticides affect the navigation capacity of foragers. By bringing the colonies closer to the field, the distances foragers need to cover might not require as much flight effort. Similarly, bees foraging close to their hive would not need to consume part of the nectar they collect to obtain energy for returning to the hive. Therefore, effects on foragers might be underestimated.

Pesticide exposure has been shown to hinder homing flight and affect foraging behaviour (Vandame et al., 1995; Bortolotti et al., 2003; Colin et al., 2004; Karise et al., 2007; Yang et al., 2008; Decourtye et al., 2011; Henry et al., 2012; Scheinder et al., 2012). Therefore, field trials should be complemented with methodologies specifically evaluating these behaviours. For further information on the protocols to run these tests, see Scheiner et al., 2013. Specific methods can evaluate the impact of pesticide exposure on fecundity, growth and development of individual honey bees (Dai et al., 2010). The development of the colony can be assessed per Delaplane et al., 2013b.