Immunocompetent ant larvae: The ontogeny of disease resistance
The ecological success of social insects can be attributed, in large part, to their remarkable ability to cope with infectious microbial organisms. Social insects can deploy numerous strategies against pathogens including behavioral, biochemical and immunological responses. While past research has revealed that social insects can generate immune function, few studies have focused on the immunocompetence during an insect’s early life stages. We hypothesized that larvae of the black carpenter ant Camponotus pennsylvanicus vaccinated with heat-killed Serratia marcescens should be less susceptible to a challenge with an active and otherwise lethal dose of the bacterium. We compared the in vivo benefits of prior vaccination on second and third instar larvae relative to Naïve and Ringer injected controls. Our results show that, regardless of the colony of origin, multiple survival parameters of vaccinated individuals following a lethal immune challenge were significantly higher than those of the latter two treatments. These results support the hypothesis that ant larvae can generate an immune response. By focusing on the ontogeny of immunity within social insect colonies, we can start addressing the mechanisms by which individual physiological immunity translates into colony-wide immunocompetence.
