Résumé
Immune priming is an observed phenomenon in both vertebrates and invertebrates, where an organism's immune system is strengthened following prior exposure to a pathogen or immune challenge. This prepares the immune system for a more efficient response when encountering the same or similar pathogens in the future. This process leads to a faster and more effective defense against threats. Immune priming can take place within an individual's lifetime or be inherited by offspring, as demonstrated in transgenerational immune priming (TGIP). Thus, both immune priming and TGIP contribute to enhanced immune responses and protection against infections.Unlike vertebrates, invertebrates primarily rely on innate immune systems lacking memory or specificity. Nevertheless, some invertebrates have the ability to modify their own or their offspring's immune responses based on previous experiences, sometimes displaying specificity towards parasites and pathogens. Instances of immune priming are widespread among invertebrates, occurring within and across generations. However, their characteristics vary based on host and parasite attributes. The evolutionary and adaptive aspects of immune priming remain unclear, leaving questions about its mechanisms and the driving conditions of its evolution unanswered.For immune priming to be adaptive, it should confer a fitness advantage to individuals expressing it in response to repeated infections, and it should incur costs in the absence of subsequent attacks by pathogens capable of persisting in the host environment. Another crucial element for immune priming to be adaptive is that its expression should be genetically encoded and thus heritable, enabling natural selection to act upon it. Substantial additive genetic variance and heritability have been identified for components of immunity and life history traits in invertebrates. Therefore, it might be reasonable to expect genetic variance and heritability for immune priming as well, although this remains uncertain.We attempted to address some of these questions using the mealworm beetle, Tenebrio molitor, as a model system.