A three-way perspective of stoichiometric changes on host–parasite interactions

• Environmental nutrients modify infection dynamics via resource quantity and quality.
• We provide a novel three-pathway perspective on the topic.
• The outcome of infection under changing nutrient levels depends on the pathway modified.
• Nutrient enrichment selects for increased host resistance and parasite virulence.

Changes in environmental nutrients play a crucial role in driving disease dynamics, but global patterns in nutrient-driven changes in disease are difficult to predict. In this paper we use ecological stoichiometry as a framework to review host–parasite interactions under changing nutrient ratios, focusing on three pathways: (i) altered host resistance and parasite virulence through host stoichiometry (ii) changed encounter or contact rates at population level, and (iii) changed host community structure. We predict that the outcome of nutrient changes on host–parasite interactions depends on which pathways are modified, and suggest that the outcome of infection could depend on the overlap in stoichiometric requirements of the host and the parasite. We hypothesize that environmental nutrient enrichment alters infectivity dynamics leading to fluctuating selection dynamics in host–parasite coevolution.