Post-embryonic Development of the Circadian Clock Seems to Correlate With Social Life Style in Bees.

Katharina Beer,Charlotte Helfrich-Förster

doi:10.3389/fcell.2020.581323

Katharina Beer, Charlotte Helfrich-Förster

Open Access

https://doi.org/10.3389/fcell.2020.581323

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Abstract

Social life style can influence many aspects of an animal’s daily life, but it has not yet been clarified, whether development of the circadian clock in social and solitary living bees differs. In a comparative study, with the social honey bee, Apis mellifera, and the solitary mason bee, Osmia bicornis, we now found indications for a differentially timed clock development in social and solitary bees. Newly emerged solitary bees showed rhythmic locomotion right away and the number of neurons in the brain that produce the clock component pigment-dispersing factor (PDF) did not change during aging of the adult solitary bee. Honey bees on the other hand, showed no circadian locomotion directly after emergence and the neuronal clock network continued to grow after emergence. Social bees appear to emerge at an early developmental stage at which the circadian clock is still immature, but bees are already able to fulfill in-hive tasks.

Highlights

Social interactions are known to influence behavioral rhythms in different animals (Sharma et al, 2004; Favreau et al, 2009; Eban-Rothschild and Bloch, 2012)
Our study indicates that the circadian clock system in newly emerged honey bees is immature at two levels: (I) behavioral output of the bee clock and (II) anatomy of the brain clock
While the neuronal honey bee clock network continues to grow moderately, but significantly after emergence, the number of clock cells expressing pigment-dispersing factor (PDF) in solitary bees does not increase after the time point of emergence

Summary

Introduction

Social interactions are known to influence behavioral rhythms in different animals (Sharma et al, 2004; Favreau et al, 2009; Eban-Rothschild and Bloch, 2012). It is largely unexplored how social life style shapes the circadian system of animals. The honey bee displays the highest form of sociality known in insects, called eusociality It is defined by (1) cooperative brood care (2) overlapping generations in one colony, and (3) reproductive division of labor with several sterile workers and one or a few fecund colony members (Winston, 1987; Michener, 2000). The last stage in their life is becoming a forager bee

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