Task allocation in the honeybee: differences in odor sensitivity between pollen and nectar foragers

A. ARENAS; EMILIA MORENO

Congreso; 5th Congress of the Latin American Association of Chemica Ecology; 2019

Division of labor and task allocation are prime enablers in the ecological success of social insects. In honeybees, differences between foragers collecting nectar and pollen are determined by the sensitivity to different gustatory stimuli (e.g. sugars). Furthermore, pollen foragers might also be more sensitive to odors, including subtle pollen volatiles that elicit foraging behavior. In this study, we aim to determine how forager sub-castes detect, perceive and learn odor stimuli, as these processes might enable the proper assessment of pollen resources. We used electroantennogram recordings (EAG) to compare the electrical response of the antennae in pollen and nectar foragers elicited by increasing concentrations (0.001; 0.01; 0.1; 1 M) of two floral odors: linalool and nonanal. Volatiles from bee-collected pollen loads were also registered. To correlate detection at the antennae with perception in individual bees, foragers were conditioned to different concentrations of the pure odors using the proboscis extension response (PER), a reflex used to condition restrained bees with sugar as reward. In this context, we performed five-conditioning trials where olfactory sensitivity was assessed by the response to the first odor-presentation before reward (?spontaneous response?). At the sensory level, we reported higher signal amplitudes in the antennas of pollen foragers than in nectar foragers for all the odors including volatiles from pollen loads. Differences were better detected at lower concentrations for nonanal trials. At the behavioral level, spontaneous responses were similar among experimental groups; however, learning performance was higher in pollen foragers, particularly among those conditioned to linalool. Our results suggest that pollen collection might be based on honeybee´s capacity to detect and respond to odors presented at low concentrations. Yet, it remains elusive if high-odor sensitivity also facilitates recognition and discrimination of pollen olfactory cues among the complex diversity of floral scents emitted by the rest of the flower