Social immunity in honeybees—Density dependence, diet, and body mass trade‐offs

Abstract

Group living is favorable to pathogen spread due to the increased risk of disease transmission among individuals. Similar to individual immune defenses, social immunity, that is antiparasite defenses mounted for the benefit of individuals other than the actor, is predicted to be altered in social groups. The eusocial honey bee (Apis mellifera) secretes glucose oxidase (GOX), an antiseptic enzyme, throughout its colony, thereby providing immune protection to other individuals in the hive. We conducted a laboratory experiment to investigate the effects of group density on social immunity, specifically GOX activity, body mass and feeding behavior in caged honey bees. Individual honeybees caged in a low group density displayed increased GOX activity relative to those kept at a high group density. In addition, we provided evidence for a trade‐off between GOX activity and body mass: Individuals caged in the low group density had a lower body mass, despite consuming more food overall. Our results provide the first experimental evidence that group density affects a social immune response in a eusocial insect. Moreover, we showed that the previously reported trade‐off between immunity and body mass extends to social immunity. GOX production appears to be costly for individuals, and potentially the colony, given that low body mass is correlated with small foraging ranges in bees. At high group densities, individuals can invest less in social immunity than at low densities, while presumably gaining shared protection from infection. Thus, there is evidence that trade‐offs at the individual level (GOX vs. body mass) can affect colony‐level fitness.

Chlorothalonil Exposure Alters Virus Susceptibility and Markers of Immunity, Nutrition, and Development in Honey Bees

“…This difference may be the result of the different modes of action exhibited by these chemistries, or it could be explained by differences in experimental design between these studies. These findings also appear to support recent work that provides evidence for a trade-off between GOX activity and body mass (Jones et al 2018), as bees treated with chlorothalonil display both increased GOX activity and decreased body weight. This suggests that the decrease in body weight may be the result of the physiologically taxing act of maintaining an enhanced social immune response.…”

Physiological and Immunological Status of Adult Honeybees (Apis mellifera) Fed Sugar Syrup Supplemented with Pentadecapeptide BPC 157

“…The colony’s strength and survival depend on the social and individual immunity of honeybees. Social immunity is based on honeybee behavioral cooperation to protect the colony against pathogens, such as hygienic behavior or thermoregulatory activity, and on the exchange in defense substances, such as antimicrobial peptide defensin-1 and antiseptic enzyme glucose oxidase (GOX) [ 15 , 16 ]. Individual immunity of honeybees is based on innate immune response, which consists of cellular (phagocytes and hemocytes) and humoral effectors including antimicrobial peptides and various proteins (e.g., vitellogenin).…”

Philosophy of Immunology

“…Interestingly, in some cases, the highest degree of immunological integration is realized at the level of a colony rather than intuitively defined individuals. For example, some data in a number of social insects such as termites and honey bees suggest that key immunological processes occur at the colony level, which has led to the concept of "social immunity" (Cremer et al 2007;Jones et al 2018) and has sometimes been used to support the superorganism hypothesis.…”