Honeybee colonies change their foraging decisions after in-hive experiences with unsuitable pollens

Abstract

Abstract Pollen is the protein resource for honeybees (Apis mellifera) and its selection affects colony development and productivity. Foragers do not consume pollen at the food source, so we expect pollen components evaluated post-ingestively not to bias their initial foraging preferences. Alternatively, pollen composition could be assessed in a delayed manner, by experiences with the pollens being processed inside the nest or with their effects on the colony. To address whether pollen foraging is mediated by in-hive experiences, we conducted dual-choice experiments to test the avoidance of pollen adulterated with amygdalin, a deterrent that causes post-ingestion malaise. In addition, we recorded pollen selection in colonies foraging in the field after being supplied or not with amygdalin-adulterated pollen from one of the dominant flowering plants (D. tenuifolia). Dual-choice experiments revealed that foragers did not avoid adulterated pollens at the foraging site; however, they could avoid unadulterated pollens that had been offered adulterated within the nest the previous days. In field experiments, pollen samples from colonies supplied with amygdalin-adulterated pollen were more diverse than controls, suggesting that pollen foraging was biased towards novel sources. Our findings support the hypothesis that pollen assessment relies on in-hive experiences mediated by pollen that causes post-ingestive malaise.