Independent and interactive effects of immune activation and larval diet on adult immune function, growth and development in the greater wax moth (Galleria mellonella)

Abstract

Organisms in the wild are likely to face multiple immune challenges as well as additional ecological stressors, yet their interactive effects on immune function are poorly understood. Insects are found to respond to cues of increased infection risk by enhancing their immune capacity. However, such adaptive plasticity in immune function may be limited by physiological and environmental constraints. Here, we investigated the effects of two environmental stressors - poor larval diet and an artificial parasite-like immune challenge at the pupal stage - on adult immune function, growth and development in the greater wax moth (Galleria mellonella). Males whose immune system was activated with an artificial parasite-like immune challenge had weaker immune response - measured as strength of encapsulation response - as adults compared to the control groups, but only when reared on high-nutrition larval diet. Immune activation did not negatively affect adult immune response in males reared on low-nutrition larval diet, indicating that poor larval diet improved the capacity of the insects to respond to repeated immune challenges. Low-nutrition larval diet also had a positive independent effect on immune capacity in females, yet it negatively affected development time and adult body mass in both sexes. As in the nature immune challenges are rarely isolated, and adverse nutritional environment may indicate an elevated risk of infection, resilience to repeated immune challenges as a response to poor nutritional conditions could provide a significant fitness advantage. This study highlights the importance of considering environmental context when investigating the effects of immune activation in insects.

The Effects of Diet on the Immune Responses of the Oriental Armyworm Mythimna separata

“…In this study, we investigated the specific immune responses of oriental armyworms fed different P:C artificial diets following bacteria challenge. Studies have generally found that there are nutrient-biased trade-offs between immune traits and life history traits, such as growth and longevity [ 11 , 32 , 34 ]. Individuals that ingested a low-nutrition diet developed more slowly, but they possessed stronger immunity, because they had to invest more energy into coping with more immune challenges which they are likely to encounter during their longer lifespan [ 11 ].…”

“…Diets that are high or low in nutrition without identifying the key nutritional element also affect the insect’s immune traits. For example, the greater wax moth Galleria mellonella larvae and adults that emerged from the larvae reared on a low-nutrition diet exhibited a stronger encapsulation response than those on a high-nutrition diet [ 11 , 32 ]. Studies also revealed that a change in the relative amount of protein and carbohydrate in the diet could affect specific immune responses and survival of the infected hosts [ 33 , 34 ].…”

Insect Models in Nutrition Research

“…Given the association between food quantity/quality and health [ 118 ], Galleria larvae have been used to study the impact of (i) a poor-quality diet and (ii) an artificial parasite-like immune challenge on pupal development, growth and adult immunity. A hostile nutritional environment can increase the risk of infection, thus provoking more frequent and robust immune responses, ultimately leading to greater fitness [ 119 ]. Categories of food differing in nutritional quality therefore affect the life history traits of Galleria [ 120 ].…”

Diet-mediated modulation on the development and phenoloxidase activity in the Alder leaf beetle larvae, Agelastica alni (L., 1758) (Coleoptera: Chrysomelidae)

“…That is, it is associated with resistance to some parasites/pathogens between species (Nigam et al, 1997). Dietary quality may also affect PO activity (Cotter et al, 2011;Kangassalo et al, 2018). Studies indicate that the food component that affects immunity is the amount of protein in diets (Lee et al, 2008, Singer et al, 2014.…”