Data from: Fight or flight? - Flight increases immune gene expression but does not help to fight an infection

Flight represents a key trait in most insects, being energetically
extremely demanding, yet often necessary for foraging and reproduction.
Additionally, dispersal via flight is especially important for species
living in fragmented landscapes. Even though, based on life-history
theory, a negative relationship may be expected between flight and
immunity, a number of previous studies have indicated flight to induce an
increased immune response. In this study, we assessed whether induced
immunity (i.e. immune gene expression) in response to 15min forced flight
treatment impacts individual survival of bacterial infection in the
Glanville fritillary butterfly (Melitaea cinxia). We were able to confirm
previous findings of flight induced immune gene expression, but still
observed substantially stronger effects on both gene expression levels and
lifespan due to bacterial infection compared to flight treatment. Even
though gene expression levels of some immunity-related genes were elevated
due to flight, these individuals did not show increased survival of
bacterial infection, indicating that flight induced immune activation does
not protect them from the negative effects of bacterial infection.
Finally, an interaction between flight and immune treatment indicated a
potential trade-off: flight treatment increased immune gene expression in
naïve individuals only, whereas in infected individuals no increase in
immune gene expression was induced by flight. Our results suggest that the
up-regulation of immune genes upon flight is based on a general stress
response rather than reflects an adaptive response to cope with potential
infections during flight or in new habitats.