Interrelationship of soil moisture and temperature to sylvatic plague cycle among prairie dogs in the Western United States.

Plague, caused by Yersinia pestis, is a flea-borne disease that is endemic in areas throughout the world due to its successful maintenance in a sylvatic cycle, mainly in areas with temperate climates. Burrowing rodents are thought to play a key role in the enzootic maintenance as well as epizootic outbreaks of plague. In the United States, prairie dogs (Cynomys), rodents (Muridae), and ground squirrels (Spermophilus) are susceptible to infection and are parasitized by fleas that transmit plague. In particular, prairie dogs can experience outbreaks that rapidly spread, which can lead to extirpation of colonies. A number of ecological parameters, including climate, are associated with these epizootics. In this study, we asked whether soil parameters, primarily moisture and temperature, are associated with outbreaks of plague in black-tailed prairie dogs and Gunnison's prairie dogs in the Western United States, and at what depth these associations were apparent. We collected publicly available county-level information on the occurrence of population declines or colony extirpation, while historical soil data was collected from SCAN and USCRN stations in counties and states where prairie dogs have been located. The analysis suggests that soil moisture at lower depths correlates with colony die-offs, in addition to temperature near the surface, with key differences within the landscape ecology that impact the occurrence of plague. Overall, the model suggests that the burrow environment may play a significant role in the epizootic spread of disease amongst black-tailed and Gunnison's prairie dogs.

Drosophila as a Model for Understanding the Insect Host of Yersinia pestis.

With the limited availability of genomic sequence information and no established methods for genetic knockdowns or the creation of transgenic fleas and flea cell lines, we have adopted Drosophila melanogaster as a model for the study of the insect life cycle of Yersinia pestis. Infection of Drosophila larvae can be used to model early colonization of fleas, while the established embryonic cell lines can be used to model insect-pathogen interactions that underlie the unique capacity of Y. pestis to colonize the gut of its flea host. In this chapter, we present the methods we developed for infection of Drosophila in vivo and in vitro.

FECAL CORTISOL LEVELS IN SCIMITAR-HORNED ORYX, ORYX DAMMAH, REVEALS DIFFERENCES BETWEEN CAPTIVE ENVIRONMENTS.

Due to the intensive management of the scimitar-horned oryx, Oryx dammah, involving both captivity and reintroductions, understanding the stress associated with environmental situations this endangered species might experience would be particularly helpful. Fecal cortisol levels were measured across seasons, between captive management programs, and among varying reproductive states in animals held at Fossil Rim Wildlife Center (FRWC) and Kansas City Zoo (KCZ). A total of 72 samples were collected from FRWC and 69 samples were collected from KCZ. The herd size and sex ratio changed for both locations in the middle of sampling due to translocations and birth. The herd sizes ranged from 25 to 28 individuals at FRWC and 22 to 24 individuals at KCZ. An ELISA was optimized and utilized to investigate fecal cortisol variances across seasons, captive management programs, and among varying reproductive states. Fecal cortisol levels ranged from 68.9 to 668.7 pg/g throughout this study, but key differences were found in response to reproductive status, environmental conditions, and social status. The highest level of fecal cortisol measured (668.7 pg/g) was in a pregnant female 9 days prior to parturition. During winter months, an increase in fecal cortisol levels occurred in both herds (FRWC 160.3 pg/g to 335.1 pg/g and KCZ 118.8 pg/g to 505.0 pg/g). In addition, when intact males were held together in an enclosure, the dominant males had lower fecal cortisol levels compared with submissive males during three of the four sampling periods. Understanding how these data relate to the physiologic stress response will require further study, but these results can be utilized to help establish expected fecal cortisol ranges in multiple environments and can aid current captive scimitar-horned oryx management programs, as well as future reintroduction efforts.