Chole H, Woodard SH, Bloch G.
Body size variation in bees: regulation, mechanisms, and relationship to social organization. Current Opinion in Insect Science [Internet]. 2019;35 :77-87.
Publisher's VersionAbstractSize polymorphism is common in bees, and is determined by environmental factors such as temperature, brood cell size, and the diet provided to developing larvae. In social bees, these factors are further influenced by intricate interactions between the queen, workers, and the developing brood which eventually determine the final size and caste of developing larvae. Environmental and social factors act in part on juvenile hormone and ecdysteroids, which are key hormonal regulators of body size and caste determination. In some social bees, body size variation is central for social organization because it structures reproductive division of labor, task allocation among workers, or both. At ecological scales, body size also impacts bee-mediated pollination services in solitary and social species by influencing floral visitation and pollination efficacy.
cholecois2019.pdf Nagari M, Gera A, Jonsson S, Bloch G.
Bumble bee workers give up sleep to care for offspring that are not their own. Current Biology [Internet]. 2019.
Publisher's VersionAbstractSleep is ubiquitous in vertebrates and invertebrates and its loss is typically associated
with reduced performance, health, or survival, for reasons that are yet unclear [1—3].
Nevertheless, some animals can reduce sleep for increasing foraging time [4], under
predation risk [5—8], during seasonal migration [9—11], or for having greater mating
opportunities [12,13]. Here we tested the hypothesis that social bumble bee (Bombus
terrestris) workers give-up sleep for improving brood-care. We combined video-
recordings, detailed behavioral analyses, sleep-deprivation experiments, and
response-threshold assessments, to characterize the sleep behavior of worker bees
and showed that immobility bouts of ≥ 5' provide a reliable proxy for sleep. We next
used this index to study sleep with an automated video-based activity monitoring
system. We found that isolated workers severely reduce sleep time in the presence of
both larvae that need to be fed, or pupae that do not. Reduced sleep was also
correlated with around-the-clock activity and wax-pot building, which are typical for
nest-founding mother queens. Cocoons, from which we removed the pupae, elicited a
similar but transient sleep-loss in tending workers, suggesting that the pupa effect on
sleep is mediated by pheromonal signals. Sleep time increased following brood
removal, but remained lower compared to control bees, suggesting that the brood
modulated sleep-need. This first evidence for brood modulation of sleep in an insect
suggests that plasticity in sleep can evolve as a mechanism to improve care for
dependent juveniles, even in social insect workers that do not care for their own
offspring.
nagaricurrentbiol1019.pdf Porath HT, Hazan E, Shpigler H, Cohen M, Band M, Ben-Shahar Y, Levanon EY, Eisenberg E, Bloch G.
RNA editing is abundant and correlates with task performance in a social bumblebee. Nature Communications [Internet]. 2019;10 (1) :1605.
Publisher's VersionAbstractColonies of the bumblebee Bombus terrestris are characterized by wide phenotypic variability among genetically similar full-sister workers, suggesting a major role for epigenetic processes. Here, we report a high level of ADAR-mediated RNA editing in the bumblebee, despite the lack of an ADAR1-homolog. We identify 1.15 million unique genomic sites, and 164 recoding sites residing in 100 protein coding genes, including ion channels, transporters, and receptors predicted to affect brain function and behavior. Some edited sites are similarly edited in other insects, cephalopods and even mammals. The global editing level of protein coding and non-coding transcripts weakly correlates with task performance (brood care vs. foraging), but not affected by dominance rank or juvenile hormone known to influence physiology and behavior. Taken together, our findings show that brain editing levels are high in naturally behaving bees, and may be regulated by relatively short-term effects associated with brood care or foraging activities.