Experimental disruption of social structure reveals totipotency in the orchid bee, Euglossa dilemma

Abstract

Eusociality has evolved multiple times across the insect phylogeny. Social insects with greater levels of social complexity tend to exhibit specialized castes with low levels of individual phenotypic plasticity. In contrast, species with simple social groups may consist of totipotent individuals that transition among behavioral and reproductive states. However, recent work has shown that in simple social groups, there can still be constraint on individual plasticity, caused by differences in maternal nourishment or social interaction. It is not well understood how these constraints arise, ultimately leading to the evolution of nonreproductive workers. Some species of orchid bees form social groups of a dominant and-one to two subordinate helpers where all individuals are reproductive. Females can also disperse to start their own nest as a solitary foundress, which includes a nonreproductive phase characterized by ovary inactivation, not typically expressed by subordinates. Little is known about individual flexibility across these trajectories. Here, using the orchid bee Euglossa dilemma, we assess the plasticity of subordinate helpers, finding that they are capable of the same behavioral, physiological, transcriptomic, and chemical changes seen in foundresses. Our results suggest that the lack of nonreproductive workers in E. dilemma is not due to a lack of subordinate plasticity.

Influence of social lifestyles on host–microbe symbioses in the bees

“…Despite being an important group of pollinators, the orchid bees (Euglossini) remain the least studied group of corbiculate bees and, at the time this paper was written, their microbiomes were undescribed. Two of the three orchid bee species included in this analysis – Euglossa dilemma and E. viridissima – exhibit some primitively eusocial behaviour, where a mother foundress and a subordinate daughter (sometimes two) administer brood care (Cocom Pech et al., 2008 ; Saleh et al., 2022 ). In these instances, there is the increased opportunity of vertically transmitted microbes becoming established across generations, although the fact that some daughters leave the nest after eclosure would suggest these relationships could be less stable than those in obligately eusocial corbiculates.…”

The influence of social lifestyles on host-microbe symbioses in the bees

“…Despite being an important group of pollinators, the orchid bees (Euglossini) remain the least studied group of corbiculate bees and, to the best of our knowledge, the microbiomes are undescribed. Two of the three orchid bee species included in this analysis -Euglossa dilemma and E. viridissimaexhibit some primitively eusocial behaviour, where a mother foundress and a subordinate daughter (sometimes two) administer brood care [Cocom Pech et al, 2008;Saleh et al, 2022]. In these instances, there is the opportunity of vertically transmitted microbes becoming established across generations, although the fact that some daughters leave the nest after eclosure would suggest these relationships could be less stable than those in obligately eusocial corbiculates.…”

Reproductive inefficiency and increased behavioral variation are associated with large group size in the orchid bee, Euglossa dilemma

“…Social insects that form small or facultatively social a liations may be especially useful as model systems for understanding the emergence of reproductive division of labor, a de ning characteristic of eusocial species (Brahma et al, 2018;Shell & Rehan, 2018). The orchid bees (Euglossini) are the only tribe in the corbiculate bees (which includes honey bees, bumblebees, and stingless bees), which is not obligately eusocial, instead exhibiting solitary or facultatively social life-histories, where females may form small, cooperatively breeding groups (Saleh et al, 2022). In orchid bee species within the genus Euglossa, social groups may consist of 2-3 females where one individual is a dominant reproductive and nest guard, and one or two individuals serve as subordinate foragers (Cocom Pech et al, 2008).…”