Correlation between octopaminergic signalling and foraging task specialisation in honeybees

Abstract

Regulation of pollen and nectar foraging in honeybees is linked to differences in the sensitivity to the reward. Octopamine (OA) participates in the processing of reward‐related information in the bee brain, being a candidate to mediate and modulate the division of labour among pollen and nectar foragers. Here we tested the hypothesis that OA affects the resource preferences of foragers. We first investigated whether oral administration of OA is involved in the transition from nectar to pollen foraging. We quantified the percentage of OA‐treated bees that switched from a sucrose solution to a pollen feeder when the sugar concentration was decreased experimentally. We also evaluated if feeding the colonies sucrose solution containing OA increases the rate of bees collecting pollen. Finally, we quantified OA and tyramine (TYR) receptor genes expression of pollen and nectar foragers in different parts of the brain, as a putative mechanism that affects the decision‐making process regarding the resource type collected. Adding OA in the food modified the probability that foragers switch from nectar to pollen collection. The proportion of pollen foragers also increased after feeding colonies with OA‐containing food. Furthermore, the expression level of the AmoctαR1 was upregulated in foragers arriving at pollen sources compared with those arriving at sugar‐water feeders. Using age‐matched pollen and nectar foragers that returned to the hive, we detected an upregulated expression of a TYR receptor gene in the suboesophageal ganglia. These findings support our prediction that OA signalling affects the decision in honeybee foragers to collect pollen or nectar.

Octopamine affects gustatory responsiveness and associative learning performance in bumble bees

“…OA receptor expression in the brains of nurses vs. foragers differs (Reim and Scheiner, 2014;Schulz and Robinson, 2001), as do OA titers (Schulz et al, 2002). Among foragers, patterns of OA receptor expression change with age (Peng et al, 2021) and OA-mediated differences may (which was not certified by peer review) is the author/funder. All rights reserved.…”

“…The copyright holder for this preprint this version posted June 24, 2022. ; https://doi.org/10.1101/2022.06.21.497037 doi: bioRxiv preprint underlie individual-level patterns of resource specialization (Arenas et al, 2021;Giray et al, 2007). For example, OA's influence on sucrose response thresholds determines the quality of food they bring back when foraging (Giray et al, 2007;Pankiw and Page Jr., 1999).…”

Use of waggle dance information in honey bees is linked to gene expression in the antennae, but not in the brain

“…Social insect behaviour and, in particular, foraging strategies are linked to gene expression in the brain (Ingram et al, 2011; Robinson et al, 2008; Toth & Robinson, 2009; Toth et al, 2010; Zayed & Robinson, 2012). Behavioural variation among workers and within foragers seems to be strongly connected to biogenic amine signalling, such as dopamine, octopamine, tyramine, and serotonin signalling (Arenas et al, 2020; Barron et al, 2002; Liang et al, 2012; Linn et al, 2020; Mercer & Menzel, 1982; Peng et al, 2020, 2021; Scheiner et al, 2002, 2017; Schulz et al, 2003). Transcriptomic differences between behavioural groups were typically studied by investigating the entire brain (e.g., Alleman et al, 2019; Liang et al, 2012; Whitfield et al, 2003).…”

Forager age and foraging state, but not cumulative foraging activity, affect biogenic amine receptor gene expression in the honeybee mushroom bodies

“…Biogenic amines are important for both division of labor and learning 17‐21 . They act as neurotransmitters, neurohormones, and neuromodulators in the central nervous system (CNS) of animals.…”

“…While the role of biogenic amines for the transition from in‐hive to foraging tasks is relatively well studied, much less is known about the role of biogenic amines after bees have transitioned to foraging. For example, biogenic amines are likely to be important to understand the diversity of foraging‐related behaviors and states, such as the tendency to be a scout or a nonscout or the likelihood to collect pollen instead of nectar 17,48‐50 . Biogenic amine receptor gene expression has been shown to be a good indicator of behavioral states 46,47,50,51 .…”