Context-dependent parental provisioning in a social insect?

Parents can protect their offspring against disease by increasing their progeny’s immune function through the direct transfer of immune-related factors, immune-elicitors, metabolites and/or antimicrobial compounds into their eggs, a phenomenon known as transgenerational immunity (TGI). While there is evidence of TGI in several insect taxa, including Hymenopteran eusocial insects, it is unknown if or how termite parents immunologically protect their offspring from disease. However, conditions within termite colonies appear to be ideal for promoting TGI; multiple generations cohabitating in microbe-rich environments that ensure both parents and offspring will repeatedly encounter the same pathogens, especially in recently established colonies. We hypothesize that female and male reproductives of the dampwood termite Zootermopsis angusticollis differentially provision their eggs according to their own immunological state to reduce the offspring’s susceptibility to disease. Reproductives were either given control treatments, a heat-killed “vaccine” or live challenge of the pathogenic bacteria Serratia marcescens. The effects of treatment on gonadal activity and egg volume were examined. Additionally, we quantified developmentally and immunologically relevant metabolites, and immune parameters in both parents and offspring. The results enhance our understanding of the mechanisms underlying context dependent parental provisioning.