The influence of parasite load on transcriptional activity and morphology of a cestode and its ant intermediate host

Abstract

Parasites with complex life cycles are known to induce phenotypic changes in their intermediate hosts to increase transmission to the final host. The magnitude of these changes could increase with the number of parasites, which would be beneficial to co‐infecting parasites. Yet, adverse effects of high parasite load (i.e. many parasites in a single host) might stress both hosts and parasites (e.g. through an increased immune response). We investigated the consequences of parasite load on the transcriptional activity and morphology of the cestode Anomotaenia brevis and its intermediate host, the ant Temnothorax nylanderi. We demonstrated that many differentially expressed host genes shifted with parasite load, and their functions indicate a stronger immune response and fight against oxidative stress in heavily infected hosts. The expression of other host genes responded to infection in an all‐or‐nothing manner, as did the morphology of the host workers. However, the cestodes became smaller when they competed with other parasites for resources from a single host. Their expression profile further indicated shifts in host immune avoidance, starvation resistance and vesicle‐mediated transport. In summary, our study reveals clear consequences of parasite load and highlights specific processes and traits affected by this.

Queen number shapes worker longevity, fecundity and gene expression in the invasive, highly polygynous antTapinoma magnum

“…In older outside workers, we found the overexpression of dual oxidase isoform X2, zinc finger proteins and fatty acid synthase. Dual oxidase induces oxidative stress to challenge gut microbiome bacteria (Ha et al, 2005;Sistermans et al, 2023), while zinc is involved in regulatory pathways (Kandel, 2009;Klug, 2005).…”