Abstract
Foraging decisions of social animals occur in the context of social groups, and thus may be subject to considerations of not only an individual’s nutritional state and nutrient input, but those of the social group in which they live. In eusocial insects, which live in colonies containing workers that forage for food that is mostly consumed by others, foraging decisions that reflect colony needs may also be considered at both the colony and individual level. If colony energy balance is perturbed, is the counteracting response occurring on the group level (a change in division of labor) or on the individual level (a change in individual foraging choices)? To address this, colony and individual level foraging behaviors were observed in two species of eusocial bees: the highly social honey bee Apis mellifera and the primitively eusocial bumble bee Bombus terrestris. After manipulations of protein (P) and carbohydrate (C) stores in colonies of both species, there were changes in multiple different behavioral responses including colony level (number of foragers, allocation to nectar and pollen foraging, nutrient mass foraged) and individual level (P and C concentration preference and loading during foraging). These results suggest both honey bee and bumble bee colonies balance nutrient needs through a combination of both colony level shifts in foraging allocation, as well as slight modulation of individual nutrient preferences. This study also uncovered colony level differences between the two bee species; honeybees balanced P intake while bumble bees balanced C intake. These patterns may reflect differences in life history traits such as perenniality and hoarding, traits that are developed in more highly social species. Overall, this study highlights the importance of considering both group and individual level behavioral responses in foraging decisions in social animals.
Highlights
What to eat? Where to forage, and for how long? Decision making in the context of food-searching behavior can be a complex process, involving multiple sensory modalities, specific forms of learning and memory, and integration of multiple different sources of external environmental and internal physiological information
If colony energy balance is perturbed, is the counteracting response occurring on the group level or on the individual level? And do these responses differ in species with different levels of sociality? We aimed to address this knowledge gap by studying behavioral responses of two bee species with different forms of social organization
This study extends findings of P to C balancing of isolated caged cohorts of honey bees (Altaye et al, 2010; Pirk et al, 2010; Paoli et al, 2014a,b) and bumble bees (Stabler et al, 2015) to the whole colony level
Summary
What to eat? Where to forage, and for how long? Decision making in the context of food-searching behavior can be a complex process, involving multiple sensory modalities, specific forms of learning and memory, and integration of multiple different sources of external environmental and internal physiological information. With a reproductive division of labor that includes a nonreproducing worker caste such as ants and honey bees, represent an extreme case in which foragers are often highly specialized on food-collecting behavior (Wilson, 1971). This food collection is often divorced from their own individual nutritional needs, and collected food is often not directly consumed, but instead shared to serve the nutritional needs of the colony. An extreme example is the Myrmecocystus honey ant, in which a specialized caste of individuals serves as living food receptacles (Burgett and Young, 1974), storing huge amounts of sweet plant secretions in their crops, but not consuming or digesting the vast majority of this food to fuel their own physiological needs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
