The complex interactions between nutrition, immunity and infection in insects

Abstract

Insects are the most diverse animal group on the planet. Their success is reflected by the diversity of habitats in which they live. However, these habitats have undergone great changes in recent decades; understanding how these changes affect insect health and fitness is an important challenge for insect conservation. In this Review, we focus on the research that links the nutritional environment with infection and immune status in insects. We first discuss the research from the field of nutritional immunology, and we then investigate how factors such as intracellular and extracellular symbionts, sociality and transgenerational effects may interact with the connection between nutrition and immunity. We show that the interactions between nutrition and resistance can be highly specific to insect species and/or infection type – this is almost certainly due to the diversity of insect social interactions and life cycles, and the varied environments in which insects live. Hence, these connections cannot be easily generalised across insects. We finally suggest that other environmental aspects – such as the use of agrochemicals and climatic factors – might also influence the interaction between nutrition and resistance, and highlight how research on these is essential.

Insect hosts are nutritional landscapes navigated by fungal pathogens

“…Pathogens obtain all nutrients from the infected host and nutrition can directly govern the outcome of host-pathogen interactions [1]. For an invading pathogen the host body represents an ecological habitat with nutrient compositions varying between host tissues and organs [2][3][4][5][6][7]. The breadth of nutrient compositions that support pathogen growth is termed the fundamental nutritional niche (FNN), and a developing pathogen can in principle deplete different body tissues to meet FNN needs specific to each pathogen growth stage [8].…”

“…During host colonization from pathogen entry, establishment, growth, and development, different types of nutrients can therefore be limiting. Single nutrients can be important for the outcome of host-pathogen interactions with the effect on the pathogen ultimately determined by the combined effects of nutrition and immune defenses [7,9]. Host-pathogen interactions can also be indirectly mediated by nutrition when specific deficiencies (e.g.…”