Developmental conditions influence adulthood resistance to infection

Nutrition is a central factor influencing immunity and resistance
to infection, but the extent to which nutrition during
development affects adult responses to infections is poorly
understood. Our study investigated how the nutritional
composition of the larval diet affects the survival, pathogen
load and food intake of adult fruit flies, Bactrocera tryoni,
after septic bacterial infection. We found a sex-specific effect of larval
diet composition on survival post-infection: survival rate was higher and
bacterial load was lower for infected females raised on a
sugar-rich larval diet than for females raised on a protein-rich
larval diet, an effect that was absent in males. Both males and
females were heavier when fed a balanced larval diet
compared with a protein- or sugar-rich diet, while body lipid
reserves were higher for those that had consumed the sugar-rich
larval diet compared with other diets. Body protein reserves were
lower for flies that had been raised on the sugar-rich larval
diet compared with other diets in males, but not females. Both
females and males shifted their nutrient intake to ingest a
sugar-rich diet when infected compared with shaminfected flies
without any effect of the larval diet, suggesting that sugar-rich
diets can be beneficial to fight off bacterial infection as shown
in previous literature. Overall, our findings show that
nutrition during early life can shape individual fitness in
adulthood.