Figure 1. Foraging behavior in colonies.

For 20 days, from drone emergence to sexual maturity, colonies were supplied daily with sugar syrup (50% w/v) ad libitum using a feeder, for harvesting by foragers from 8:30 a.m. to 11:30 a.m.; the syrup was replaced with crushed pollen and water for the remainder of the day. While the hives were fed during the exposure period, foraging behavior was monitored in 44 colonies from 22 tunnel compartments. (A) Illustration of the experimental platform; (B) cumulative foraged syrup; and (C) cumulative foraged pollen. The data represent the mean± the standard deviation of the daily cumulative foraged quantity observed in each compartment (1 feeder for 2 hives). For each treatment, the data correspond to the set of values from 4 experiments conducted between 2012 and 2014 (n = 11). Statistical analyses of the growth rates of cumulative foraging (α) and maximum cumulative quantities (β) were performed using a generalized linear mixed model with a random effect on the different experiments.