Submitted to: Animal Behaviour
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2016
Publication Date: 2/1/2017
Publication URL: https://handle.nal.usda.gov/10113/5695417
Citation: Traynor, K.S., Wang, Y., Brent, C.S., Amdam, G., Page, R.E. 2017. Young and old honey bee (Apis mellifera) larvae differentially prime the developmental maturation of their caregivers. Animal Behaviour. 124(1):193-202.

Interpretive Summary: In the honey bee, nurse bees supply different diets to young and old developing bee larvae (brood). Brood may signal nurses to adjust the diet they are feeding, causing either rapid but short-lived changes in nurse behavior, or gradual but longer-term changes. Long-term changes caused by the brood might persist after a nurse transitions into a foraging worker bee. Brood are known to emit age-dependent chemical signals that influence nurse behavior, but the roles and specific effects of these signals are incompletely known. An ARS scientist from Maricopa, AZ and collaborators found the early environment of maturing nurses altered the development of their ovaries and caused hormonal changes known to regulate behavior and reproduction. Brood environments also affected the timing of worker bee transition from nursing to foraging, and the preference for collecting nectar over pollen while foraging. Collectively these results support the view that brood have a lasting impact on the behavior and development of their caregivers that influences colony dynamics.

Technical Abstract: In eusocial insects daughters rear the offspring of the queen to adulthood. In the honey bee, Apis mellifera, nurses differentially regulate larval nutrition. Among worker-destined larvae, younger instars receive an unrestricted diet paralleling that of queen larvae in protein composition but with reduced sugar content, while older instars receive a restricted diet comparable to that of queen diet in sugar content but with reduced protein content. This differential feeding behaviour by the nurses may result from the compositionally divergent pheromones emitted by young and old larvae. To determine whether larvae and their associated pheromones have a priming effect on nurse behaviour, we examined the behavioural and physiological effects on young workers exposed for the first ten days of their adult development to the presence of young larvae, old larvae, or the young larval pheromone e-beta ocimene (eß) relative to a broodless control population. The early environment of maturing caregivers was found to alter the circulating titres of vitellogenin, and juvenile hormone in nurses. The brood environments also significantly reduced the age of first foraging (AFF), while priming with eß increased pollen collection. Collectively these results support the view that the reproductive regulatory network is sensitive to colony conditions, and this network is used to mediate the foraging division of labour.