Figure 1

(A) Effects of pollen diets on Crithidia infection in individual Bombus impatiens workers. Bees were inoculated with Crithidia and fed a monofloral pollen diet commonly grown in large monocultures in agroecosystems: sunflower (Helianthus annuus; Sun), buckwheat (Fagopyrum cymosum; Buck), rapeseed (Brassica campestris; Rape), or a mixed diet composed of equal weights of the three monofloral pollens (Mix). (B) Pollen diets did not significantly affect rate of worker death over the 7 d experiment shown in (A). Y-axis shows exponentiated hazard rates ±1 standard error. (C) Crithidia infection was allowed to build for one week post-inoculation before providing pollen treatments: sunflower (Sun), buckwheat (Buck), or a wildflower pollen mixture (WF Mix). (D) Inoculated bees were fed sunflower pollen from two sources, China (CN) or USA (USA), or a control wildflower pollen mixture (WF Mix). Bars and error bars indicate negative binomial model means ±1 standard error back-transformed (i.e., exponentiated) from the scale of the linear predictor. Crithidia counts represent raw counts of cells diluted in a gut homogenate. Error bars represent uncertainty in fixed effects portions of models only, and do not account for variability due to random effects. Different letters above each bar within panels indicate significant differences based on Tukey’s HSD tests.