Muscle in the caterpillar Manduca sexta responds to an immune challenge, but at a cost, suggesting a physiological trade-off

Abstract

Although skeletal muscle is a specialized tissue that provides the motor for movement, it also participates in other functions, including the immune response. However, little is known about the effects of this multi-tasking on muscle. We show that muscle loses some of its capacity while it is participating in the immune response. Caterpillars (Manduca sexta) were exposed to an immune challenge, predator stress, or a combination of immune challenge and predator stress. The expression of immune genes (toll-1, domeless, cactus, tube and attacin) increased in body wall muscle after caterpillar exposure to an immune challenge. Muscle also showed a reduction in the amount of the energy storage molecule glycogen. During an immune challenge, the force of the defensive strike, an important anti-predator behaviour in M. sexta, was reduced. Caterpillars were also less able to defend themselves against a common enemy, the wasp Cotesia congregata, suggesting that the effect on muscle is biologically significant. Our results support the concept of an integrated defense system in which life-threatening events activate organism- wide responses. We suggest that increased mortality from predation is a non-immunological cost of infection in M. sexta. Our study also suggests that one reason non-immunological costs of infection exist is because of the participation of diverse organs, such as muscle, in immunity.

’Disease-smart’ assisted migration can enhance population fitness and increase resistance to pathogens via immune priming

“…Immune priming often involves a trade-off with reproductive success. For instance, in species like Manduca sexta and mosquitoes, offspring of primed parents tend to lay fewer eggs compared to those from control parents, indicating a trade-off between immune priming and egg production (Adamo et al 2023;Cime-Castillo et al 2023). We observed this trade-off in our study using Tribolium as well, primed females produced fewer offspring than their unprimed counterparts.…”