PLAGUE IN A COMPLEX OF WHITE-TAILED PRAIRIE DOGS AND ASSOCIATED SMALLMAMMALS IN WYOMING

Fleas were collected from white-tailed prairie dogs (Cynomys leucurus) and other small mammals trapped on six grids during a field study nea r Meeteetse (Wyoming, USA) in 1989 and 1990 to investigate the dynamic s of plague in this rodent population. Fleas were identified and teste d for Yersinia pestis by mouse inoculation. Yersinia pestis-positive f leas were found on prairie dogs and in their burrows. Flea species on prairie dogs changed from spring to late summer. White-tailed prairie dog numbers were significantly lower in the presence of Y. pestis-posi tive fleas; however, affected populations generally recovered 1 to 2 y r following absence of detectable plague. Grids where recovery occurre d had a high proportion of juvenile male prairie dogs. Eighteen flea s pecies were identified on small mammals, six of which were infected wi th Y. pestis. Some flea species were associated with a particular smal l mammal species, while others were found on a broad range of host spe cies. Flea species most important in the potential inter-change Y. pes tis between associated small mammals and white-tailed prairie dogs wer e Oropsylla tuberculata cynomuris, Oropsylla idahoensis, and Oropsylla labis. Plague cycled through the white-tailed prairie dog complex in an unpredictable manner. Each summer the complex was a mixture of colo nies variously impacted by plague: some were declining, some were unaf fected by plague, and others were recovering from plague population de clines. These data provide insight into the dynamics of plague in whit e-tailed prairie dog complexes, but predicting movement of plague is n ot yet possible and the role of associated mammals in maintenance of p lague is not understood.