Change in foraging preferences after experiencing adulterated pollens inside beehives

ROCIO LAJAD; ARENAS ANDRÉS

Congreso; XI Congreso Argentino y XII Congreso Latinoamericano de Entomología 2022. 26.; 2022

Change in foraging preferences after experiencing adulterated pollens inside beehivesPollen is the main protein resource for honeybees Apis mellifera L. (Hymenoptera: Apidae). Its composition differs among plant species, so pollen selection affects colony development and productivity. Fresh pollen is not consumed by bees at the food source, therefore, foragers’ decisions on pollen might not rely on components such as proteins, lipids and/or some toxic compounds, as they can only be evaluated after resource ingestion. On the contrary, pollen is mainly consumed by young workers inside the hive, who also process and partially digest pollen for their nestmates. We hypothesized that adjustment of pollen foraging preferences requires the resource to be experienced within the nest after being processed. To study whether foraging preferences change after in-hive experiences with pollen, we performed dual-choice experiments with hives confined in flying cages (9x3x2m). There, we compared preferences of bees that had been trained to visit a station with two feeders, each offering a different monofloral pollen (Brassica napus or Diplotaxis tenuifolia), 2 days after one of these pollens was offered adulterated inside the nest. One at a time, pollens were adulterated with amygdalin (0.1 M), a deterrent naturally found in almond pollen that causes post-ingestion malaise in bees, thereby reducing pollen suitability. In addition, we conducted a second experiment in the field, in which we compared colony foraging preferences by means of the composition of pollen samples trapped at the entrance of the hives. Samples were taken after the offering of amygdalin-adulterated pollen from one of the dominant flowering plants in the field (D. tenuifolia). In both experiments we included control coloniesin which pollen was offered in the same way as in the treated colonies but with no added amygdalin. Results from dual-choice experiment indicated that foragers in the treated colonies avoided those pollens that had been experienced as unsuitable within the nest. In field experiment, pollen samples from treated colonies were more diverse than in the controls (estimated by Shannon’s H-index), suggesting that experiences with an unsuitable highly available pollen biased foraging towards pollens from rare or less represented plants. Altogether, our findings suggest that assessment of pollen composition requires the resource to be experienced inside the nest.