The occurrence of immune priming can be species-specific in entomopathogens

Infection risk by oral contamination does not induce immune priming in the mealworm beetle (Tenebrio molitor) but triggers behavioral and physiological responses

“…However, this was not the case. These results, together with previous findings demonstrating that immune priming could be induced through injection or septic wounding (4,15,46,52), clearly suggest that the oral route of contamination by bacterial pathogens represents a marginal selective pressure for the evolution of immune priming in T. molitor. In contrast, septic wounding appears to have played a more significant role.…”

“…By contrast, food contaminated with S. marcescens, another deadly entomopathogen but Gram(-) bacterium, was consumed as much as control food, as were foods contaminated with S. aureus and E. coli, generalist bacteria inducing almost no virulence in our assays. Previous studies suggested that Gram(+) bacterial pathogens, particularly Bacilli, might have played a specific role in shaping immunity of the mealworm beetle with regard to the evolution of immune priming (15,(44)(45)(46). Our results confirm that these bacteria are recognized as an important threat for the mealworm beetle, which may also have evolved the ability to specifically recognize contaminated food and adjust its feeding behavior accordingly.…”

“…Neither B. cereus nor S. marcescens induced any long-lasting protective effect in larvae or adults that ingested living or dead bacteria prior septic wounding. This sharply contrasts with the long-term immune priming conferred by dead bacterial injection (15,46). Immune priming is therefore probably effective only if pathogens or antigens have reached the hemocoel of insects, where they are in direct contact with circulating hemocytes, important components of immune activation (14).…”

“…This slight elevation in the short-term immune response was observed only after the ingestion of high doses of S. whereas similar high doses of dead B. cereus were slightly deleterious. Therefore, the stimulation of the adult's immune system appears to be pathogen-dependent, as is the long-term immune priming after injected vaccination (15,46). The survival of T. molitor after septic wounding is complicated by our evidence of stage-dependent sensitivity to the wounding itself.…”

An Invertebrate Host to Study Fungal Infections, Mycotoxins and Antifungal Drugs: Tenebrio molitor

“…Another important attribute related to immune priming is its species-specific character. Larvae that were exposed two times to the same pathogen ( M. anisopliae ) presented a higher survival rate than larvae that were challenged with this fungus and later exposed to Bacillus thuringiensis and Serratia marcescens [64]. In addition, immune priming has the ability to be transmitted between generations.…”