Ontogeny of division of labor in a facultatively eusocial sweat bee Megalopta genalis

Abstract

In eusocial nests, colony task are divided among queens and workers, but how this division of labor develops is unknown for most species. We compared division of labor and aggressive behavior among queens and workers in the facultatively eusocial bee, Megalopta genalis, using nests with established queen-worker pairs and nests in which the incipient worker had recently emerged. We find that the majority of aggression is directed from queens toward workers in both incipient and established relationships. Established workers forage and perform trophallaxis as donors more frequently than queens, but both queens and workers perform trophallaxis as donors when workers are young. Queens spend significantly more time nest guarding than incipient and established workers, perhaps because older workers spend more time foraging and incipient workers spend significantly more time in cells than do queens. Our results show that the development of worker behavior involves dynamic temporal changes in task performance among queens and workers during the 10 days after worker emergence. During this establishment period, queens engage in maternal care by feeding their daughters, but are also aggressive toward them. This may be a mechanism by which queens coerce their daughters into becoming non-reproductive workers.

Dominant-subordinate social interactions and subordinate behavioral responses in the primitively eusocial sweat bee Augochlora phoemonoe (Hymenoptera: Halictidae)

“…In primitively eusocial bees, although some type of chemical communication could operate (Breed et al 1978;Greenberg 1988;Rehan and Richards 2013), colony integration is achieved by means of behavioral interactions between dominant and subordinate individuals. Halictid bees belong to this second class, where the outcome of social competition is largely governed by physical interactions (reviewed in Michener 1990;Pabalan et al 2000;Smith et al 2009;Kapheim et al 2016).…”

Trophallaxis in weakly social bees (Apoidea)

“…Michener, ; Hunt & Nalepa, and references therein). First, although sociality repeatedly evolved in halictid bees, trophallaxis is rare, and was documented in eusocial forms only recently (see Kukuk, ; Wcislo & Gonzalez, ; Kapheim et al , 2015). The then‐absence of trophallaxis in eusocial Halictidae led Michener to conclude that it was not necessary for the evolution of caste‐based societies (references in Michener, ).…”

“…Food transfer among adults of facultatively eusocial halictid bees, where it occurs, is sometimes the reverse of this pattern (Wcislo & Gonzalez, ; Kapheim et al , 2015). In established two‐bee social nests, liquid food typically flows from the foraging bee to the nest resident (i.e.…”

“…cit .). Established workers (older > 10 days post‐eclosion) forage and perform trophallaxis as donors, more than queens, but this difference is not apparent when workers are young (< 10 days post‐eclosion) (Kapheim et al , 2015). Thus, the initial recipient is fed in the context of dominance interactions suggesting ritualised competition may be important.…”

Juvenile hormone, but not nutrition or social cues, affects reproductive maturation in solitary alkali bees (Nomia melanderi)

“…Similarly, treatment with the juvenile hormone (JH) 47 analog methoprene leads to accelerated ovarian development in queen paper wasps (Polistes 48 canadensis), but instead increases foraging activity in workers (Giray et al, 2005). Finally, social cues, 49 such as aggression from the queen, can repress endocrine pathways, and thus ovary development, in 50 worker bumble bees (Bombus impatiens) and social halictid bees (Megalopta genalis), but aggression 51 directed from workers toward queens does not have the same effect (Kapheim et al, 2016;Padilla et al, 52 2016;Smith et al, 2009). Understanding how these differences in sensitivity to physiological and 53 environmental cues arises among females and contributes to variation in reproductive activity is thus 54 key to understanding the origins of social insect castes.…”