Food scouting occurs daily and is strongly influenced by colony need and seasonal floral fluctuation, and food scouts search for new flower patches and evaluate how profitable they are as sources of sustenance. The tendency to scout is influenced by both inherited and environmental factors. The two forms of scouting behaviour also have very different search targets: they use different criteria to evaluate their targets and are influenced by different social environments. Nest scouts recruit other individuals to investigate potential locations before the entire swarm moves.
The same is true for nest scouts after colony reproduction (fission), a small group of bees search for new nest sites and then share information about these sites with the majority of the bees that have formed a temporary ‘swarm’, awaiting a move to a permanent location. Only a minority of a colony's adult worker bees act as food scouts and search for new food sources on their own the majority of the foraging force wait to be ‘recruited’ and rely on information provided by scout bees to guide their foraging. Scout bees seek new resources for their colony, and they use a variety of similar and different behaviours to do so across two very different ecological contexts: foraging for floral resources and searching for a new nest site. Scouting in colonies of the honeybee, Apis mellifera, provides an excellent system to study this question. Specifically, it is not known whether such consistent tendencies are associated with similar patterns of brain gene expression. Relatively little is known about the molecular basis of consistent tendencies that are manifest across different behavioural and ecological contexts. This phenomenon exists in a wide range of species, from insects to primates, and also involves many different types of behaviour, including aggressiveness, fearfulness, risk-taking and exploratory or novelty-seeking behaviour. Many such differences are heritable, relatively stable over the lifetime of an animal, and consistent across distinct behavioural and ecological contexts, in both humans and non-human animals. Individual differences in behaviour are ubiquitous in nature. These results indicate that consistent behavioural tendencies across different ecological contexts involve a mixture of similarities and differences in brain gene expression.
We also found that genes related to four neurotransmitter systems were part of a shared brain molecular signature in both types of scouts, and the two types of scouts were more similar for genes related to glutamate and GABA than catecholamine or acetylcholine signalling. Class prediction and ‘leave-one-out’ cross-validation analyses revealed that a bee's role as a scout in either context could be predicted with 92.5% success using 89 genes at minimum. Brain gene expression profiles in food-source and nest-site scouts showed a significant overlap, despite large expression differences associated with the two different contexts. We explored this issue by studying scouting in honeybees in two different behavioural and ecological contexts: finding new sources of floral food resources and finding a new nest site. Individual differences in behaviour are often consistent across time and contexts, but it is not clear whether such consistency is reflected at the molecular level.
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