Diet Selection and Parasite Infection in Peromyscus leucopus and P. maniculatus: Do wild mice alter foraging behavior to combat intestinal parasites?

Abstract

The motivation of this study is to explore possible changes in foraging behavior during parasite infection and malnutrition in a population of wild white-footed mice and deer mice (Peromyscus leucopus and P. maniculatus). Prior literature demonstrates that some animals may alter diet selection during infection to influence immune responses or to self-medicate (Lozano 1991, Lisonbee et al. 2009). This could be an adaptive form of resistance as part of the coevolutionary arms race between parasites and their hosts. In addition to their prevalence in wildlife, intestinal parasites present a substantial health and economic burden for human populations, particularly in developing nations. Billions of people worldwide are malnourished and infected with gastrointestinal parasites, including helminths and protozoa. The complex interactions between diet, immunity, and parasitic infection have been referred to as a negative spiral because malnutrition can be both a consequence and a predisposing factor of infection (Koski 2001). By studying how wild animals mitigate the impact of parasite infection through diet modulation, we may learn useful information that can be applied to controlling human infections. Moreover, there are very few drugs available to treat parasitic infections and there is a threat of resistant strains emerging in humans, livestock, and poultry. Therefore, research that addresses compounds that can potentially be used as a springboard for drug development, are valuable to global health efforts. This study uses fecal DNA metabarcoding to characterize diet and explore relationships with body condition (as an indicator of malnutrition) and parasite infection. Results indicate that relative read abundance (RRA) of nuts, largely driven by acorns (Quercus spp.) was significantly greater during nematode infection compared to mice that did not have nematodes or had been dewormed (p = 0.000154). By contrast, RRA of dry dehiscent fruit, largely driven by legumes, was significantly lower during nematode infection (p = 0.00249). Given that acorns tend to have a high fat content, a low fiber content, and contain higher concentrations of condensed tannins, which have been shown to have anthelmintic effects, these results may suggest that nematode-infected mice alter their diet based on nutrient composition and/or presence of anthelmintic compounds. No significant relationships were found between overall diet richness and infection status or body condition. Future research can elucidate the evolutionary significance of these dietary changes, as well as the potential applications for infection control programs and drug development.