Honeybee rebel workers preferentially respond to high concentrations of sucrose

Abstract

The honeybee is one of several eusocial species with a complex set of anatomical, physiological, and behavioural traits that are correlated with foraging preferences. Sensory sensitivity to sucrose is associated with the foraging preferences of workers, with individuals that are less sensitive to sugar preferring to forage for nectar and those that are highly sensitive to sucrose preferring to forage for pollen. In this study, we test this hypothesis by comparing the sucrose responsiveness of genetically similar normal and rebel honeybee workers, which present different foraging preferences. We found that rebels, which prefer to forage for nectar and have a higher reproductive potential than normal workers, are characterised by sucrose sensitivity that is lower than that of normal workers. Moreover, we show that in both rebel and normal workers, sensitivity to sugar in nectar is lower in workers when their ovaries contain more ovarioles. The results confirm the prediction that bees present a foraging preference depending on their response thresholds to sucrose in solution. However, compared with previous studies, our investigation does not support the assumption that reproductive workers are more sensitive to sucrose concentrations in nectar.

Humoral and Cellular Defense Mechanisms in Rebel Workers of Apis mellifera

“…Thus, workers developing at larval stage in a queenless colony become relatively selfish individuals with higher reproductive potential than those that develop in a colony with a queen. These workers called rebel workers are characterized not only by their increased reproductive potential but also other altered anatomical features (e.g., less developed HGs, larger mandibular glands; [ 20 ]), shortened preimaginal development [ 22 ], prolonged life [ 23 ], different foraging preferences [ 24 ], tendency to drift to other colonies [ 25 ], increased sucrose sensitivity [ 26 ], energy reserves and protein concentrations in fat body [ 4 ], and increased learning ability [ 27 ].…”

Honeybee workers with higher reproductive potential have a greater learning ability

“…This result indicates that there is no trade-off between these two biological functions in honeybee workers. Previous studies showed that rebel workers were less sensitive than normal workers to the sucrose concentration in solutions and did not respond to a solution with a low sugar concentration (Karolina Kuszewska et al 2019). The difference in sucrose sensitivity between these two groups of workers can influence the speed of learning.…”

“…However, we think that OA does not have much of an impact on the results of our study for two reasons. First, rebel workers, which learned faster, are less sensitive to sugar concentration than normal workers, which learned slower (Kuszewska et al 2019). Second, in our study, we used 21day-old bees, all of which were foragers.…”

“…These workers are called rebel workers (M Woyciechowski and Kuszewska 2012), and studies have shown that these individuals lay eggs more often than normal workers, even if they remain in a colony with a queen (Karolina Kuszewska et al 2018c). Compared to normal workers, rebel workers are characterised not only by their increased reproductive potential but also by their prolonged life (Karolina Kuszewska et al 2017), different foraging preferences (Kuszewska et al 2018b), tendency to drift to other colonies (Karolina Kuszewska et al 2018a) and increased sucrose sensitivity (Karolina Kuszewska et al 2019).…”

Reproductive Potential Accelerates Preimaginal Development of Rebel Workers in Apis mellifera

“…Moreover, their ovaries are activated regardless of whether they live in queen-less or queen-right colonies [ 14 , 15 , 16 , 17 , 18 ]. Moreover, rebels typically have prolonged life [ 16 ], different foraging preferences [ 18 ], tendency to drift to other colonies [ 17 ], increased sucrose sensitivity [ 19 ], increased energy reserves and protein concentrations in the fat body [ 20 ], and increased learning ability [ 21 ]. We posited that rebels are not only similar to queens in some anatomical, morphological and behavioral features, but also develop in a shorter time in comparison to normal workers, i.e., they might undergo shorter ontogeny.…”