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Effects of infections with sylvatic species Trichinella, T. nativa or T. pseudospiralis, on the diel locomotory activity and locomotory activity pattern of an indigenous rodent host, the deer mouse (Peromyscus maniculatus), were assessed in a familiar environment and during the process of familiarization in a novel environment. Infection with muscle-encapsulating T. nativa severely reduced overall locomotory activity and changed locomotory activity patterns in a dose dependent fashion. In contrast, T. pseudospiralis infection had no such effects on diel locomotory activity. Infection with these nonencapsulating nematodes also changed locomotory activity patterns, but effects were independent of inoculation dose. Trichinella pseudospiralis infection almost completely reversed the locomotory exploration patterns of mice. Both T. nativa- and T. pseudospiralis-infected mice spent more time in shelter than did sham-inoculated conspecifics. Biological characterization of these infections in deer mice revealed striking departures from the conventional course of infection as typified by synanthropic trichinellosis in laboratory mice, and provided further insight into the relationship between the major phases of infection and the observed behavioral changes. Altered behaviors of infected deer mice are discussed in terms of their consequences on host fitness and survival, as well as parasite transmission. The study establishes links between behavioral observations derived from synanthropic and laboratory rodent-T. spiralis host-parasite associations and their sylvatic counterparts. It provides the behavioral underpinnings for future assessments of the role of wild rodents in the transmission of sylvatic trichinelloses.

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The American kestrel (Falco sparverius) - Trichinella pseudospiralis host-parasite association was used as a model to study the effect of infection on (1) mate choice of female kestrels and (2) competitive abilities of male kestrels. In 34 choice tests, female selection of infected or uninfected males was random. Male competitive abilities was assessed by observing interactions between infected and uninfected individuals in a pen with a caged female and a single nest box. In 8 of 11 trials, uninfected males spent more time in the section closest to the female than their infected rivals, and performed more chases, attacks, and displacements than the latter. These results suggest that variation in male quality is determined in part by resistance to parasitism and can affect competition for nesting territories. Females may not have evolved mechanisms to detect parasitized males because these males are unlikely to outcompete uninfected males when territories are in limited supply.

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No description available.