From field to food-will pesticide-contaminated pollen diet lead to a contamination of royal jelly?

The contamination of bee products, e.g., bee bread, by pesticides is an increasing problem of beekeeping in rural areas. Bee bread is used by nurse bees to produce larval food. However, the fate of pesticides originating from the pollen during this process is unknown. Over the entire period of queen rearing, adult honeybees in queenless mini-hives were fed with a pollen-honey diet containing a cocktail of 13 commonly used pesticides in high concentrations (34-920 mu g/kg). Royal jelly (RJ) harvested from queen cells was subjected to a multi-residue analysis. Seven substances were rediscovered in traces (76.5% of all detections are below 1 mu g/kg) with at most 0.016% of the original pesticide concentrations of the fed diet. Considering this extraordinary low contamination of RJ, it seems unlikely that pesticides, if used according to the approved application instructions, would impair the development and health of honeybee queens. Possible reasons for the low residue levels in RJ are discussed.