Solitary bees reduce investment in communication compared with their social relatives

Abstract

Social animals must communicate to define group membership and coordinate social organization. For social insects, communication is predominantly mediated through chemical signals, and as social complexity increases, so does the requirement for a greater diversity of signals. This relationship is particularly true for advanced eusocial insects, including ants, bees, and wasps, whose chemical communication systems have been well-characterized. However, we know surprisingly little about how these communication systems evolve during the transition between solitary and group living. Here, we demonstrate that the sensory systems associated with signal perception are evolutionarily labile. In particular, we show that differences in signal production and perception are tightly associated with changes in social behavior in halictid bees. Our results suggest that social species require a greater investment in communication than their solitary counterparts and that species that have reverted from eusociality to solitary living have repeatedly reduced investment in these potentially costly sensory perception systems.

Cryptic castes, social context and colony defence in a social bee, Tetragonula carbonaria

“…Similarly, higher sensilla density may allow T. carbonaria guards to identify intruders more quickly and or accurately than foragers, especially if these sensilla contain receptors for nest recognition signals. This interpretation of a link between sensilla density and efficient signal detection is consistent with reported differences in the density of sensilla between social and solitary bees, which presumably reflect a greater investment in antennal receptor organs in social species (Wittwer et al, 2017).…”

Sexual selection and organs of sense: Darwin’s neglected insight

“…Adult grasshoppers reared on synthetic diets with fewer flavours or odours had lower numbers of sensilla (Rogers & Simpson, 1997;Bernays & Chapman, 1998), presumably reflecting a redundancy in sensory requirements. Similar patterns have been documented for social signals, where evolutionary transitions from social to solitary lifestyles in halictid bees are accompanied by lower investment in antennal sensilla (Wittwer et al, 2017). Studies of anticipatory life-history investment also provide insights into the costs of receptor organ development.…”

Antennal Protein Profile in Honeybees: Caste and Task Matter More Than Age

“…The large repertoire of compounds secreted by pheromonal glands in social insects, together with the variety of volatiles present in the environment need to be analyzed by an efficient olfactory system ( Wittwer et al, 2017 ). Differences in the perception of environmental and conspecific odorants between castes or during the life cycle has so far received limited attention compared to other aspects of phenotype plasticity ( Kelber et al, 2010 ; Zhang et al, 2016 ; Nie et al, 2018 ).…”