Effects of coccidian parasites on the personality and physiological traits of plateau pika

We measured the variation in food intake, body mass, fecal cortisol concentration, resting metabolic rate (RMR), and exploration in 30 plateau pikas fed with Eimeria coccidia oocysts (COs), anthelmintic, and normal saline (NS), respectively. On the 5^th day, the number of CO-fed pikas reached the peak, and the population of the CO-fed group was significantly higher than that of the anthelmintic-fed group and control group (NS-fed group) (P < 0.05). On the 18^th day, there was no significant difference in food intake between the CO-fed group and the control group (P > 0.05), but the food intake was significantly lower than that in the anthelmintic-fed group (P < 0.05). On the 8^th day, the fecal cortisol concentration in the CO-fed group and anthelmintic-fed group was significantly higher than that in the control group (P < 0.05). On the 18^th day, the fecal cortisol concentration and RMR in the CO-fed group and the control group were significantly higher than those in the anthelmintic-fed group (P < 0.05). On the 5^th day, exploration in the CO-fed group was significantly lower than that in the anthelmintic-fed group and the control group (P < 0.05). When Eimeria coccidia infected plateau pika, it increased their cortisol concentration, decreased their RMR, and weakened their exploration, which reduced the risk of predation and promoted the transmission rate of Eimeria coccidia in plateau pikas. This study provides a new basis for using Eimeria coccidia as a potential biological control agent to control plateau pika populations.