Regulation of pollen and nectar foraging in honeybees: changes in gustatory perception, learning and memory in bees arriving or departing from food sources.

EMILIA MORENO; ANDRÉS ARENAS

Encuentro; III Reunión de Biología del Comportamiento del Cono Sur 2021 (Brasil).; 2021

In honeybees, foraging task specialization, where foragers are specialized in the collection of pollen or nectar as food sources, is linked to differences in bees´ sensitivity to flower?s rewards. In behavioral bioassays, the offering of successive increasing concentrations of sucrose solutions showed that nectar foragers start responding at higher concentrations, then are less sensitive, than pollen foragers. We have interpreted that a low gustatory sensitivity enables nectar foragers to be more likely to visit concentrated sugar sources. Furthermore, because pollen foragers are less demanding regarding the reward, they also learn better with nutritional and non-nutritional compounds of pollen. So far, differences in gustatory perception and learning have been observed between nectar and pollen foragers returning to the hive, but have not yet been studied in bees at the beginning of their foraging visit (i.e. highly motivated to forage). By means of the proboscis extension reflex (PER), an innate response elicited when sucrose solution contacts the antennae, we measured the gustatory sensitivity of foragers arriving or departing from pollen or sugar feeders. In addition, we olfactory conditioned pollen foragers to study differences in acquisition and retention of odour ? sucrose associations vs. odour ? sucrose + pollen associations, at the beginning and at the end of the visits. Interestingly, at arrivals, pollen foragers were less responsive (i.e., present lower gustatory sensitivity) than nectar foragers and performed better with the dual (sucrose + pollen) reinforcement than with sucrose alone. As it was expected for departures, pollen foragers showed higher gustatory sensitivity than nectar foragers and performed similarly during conditioning with or without pollen reward. Our results are consistent with the fact that low sucrose responsiveness at the beginning of the foraging visit would prevent pollen foragers from being attracted to nectar sources while enable them to better learn source-related cues reinforced with pollen.