Foraging Behavior in Peromyscus leucopus Infected with Gastrointestinal Parasites

Abstract

Gastrointestinal parasite infection poses a significant threat to host fitness and can contribute to increasing deterioration in host health when combined with malnutrition. Because of this link between nutrition and infection, hosts may select foods when foraging that are higher in nutrients or phytochemicals that may help resist gastrointestinal parasite infection. Previous research has established these behaviors in domestic and laboratory animals, however research has not as thoroughly explored these behaviors among wild hosts in a natural foraging context. In this study, it was hypothesized that white-footed mice (Peromyscus leucopus) adjust their diet and eat more foods with advantageous nutrient or phytochemical content when infected with gastrointestinal parasites, such as coccidia, nematodes and cestodes, and eat less of these foods when treated with anthelminthic treatment to remove gastrointestinal nematode infection. Because repeat-doses of anthelminthic treatment are known to further decrease nematode infection, it was also hypothesized that repeat-doses of anthelminthic treatment would contribute to greater changes in diet. These hypotheses were tested among wild white-footed mice that were caught and treated with anthelminthic medication over the course of a three-month field experiment. Fecal egg counts were used to assess parasite burden of coccidia, nematode, and cestode eggs and oocysts, and DNA metabarcoding was used to evaluate diet content from plant DNA present in fecal samples. The results of this experiment suggest that mice consume greater amounts of protein and tannin-rich plant families when infected with GI parasites and eat less of plant families with advantageous phytochemicals after anthelminthic treatment. These results did not suggest an increasing effect on diet with repeat-doses of anthelminthic treatment. Overall, these findings suggest that wild white-footed mice alter diet selection to ameliorate or resist the negative effects of gastrointestinal parasite infection.