Data from: Dietary protein and carbohydrates affect immune function and performance in a specialist herbivore insect (Manduca sexta)

Nutrition structures ecology and evolution across all scales of biological
organization. It is well known that nutrition can have direct effects on
performance and fitness, but indirect effects on physiological systems
that mediate biotic interactions have been studied less frequently. Here,
we focus on the interaction between nutrition, performance, and the immune
system in a specialist herbivorous insect, Manduca sexta. We used a
conceptual framework in nutritional ecology (the geometric framework) to
examine how changes in diet quality affect aspects of the immune system
used for defense against parasitoids. We raised caterpillars throughout
their entire larval development on five different experimental diets that
varied in protein and carbohydrate content and measured five aspects of
the immune system: encapsulation, phenoloxidase activity, prophenoloxidase
activity, total hemolymph protein, and hemocyte density. Overall,
different parts of the immune function varied in response to interactions
between carbohydrates, protein, and intake, but protein reductions had the
largest impacts—mostly detrimental. In addition, our data suggest that
diet quality mediates the relationship between performance (growth and
survival) and immune function, as well as trade-offs among different
components of immune function. Our work is the first to examine the
interplay between nutrition, performance, and immune function with the
geometric framework in a specialist insect herbivore.