Ecology of Helminth Parasitism in the Bobcat from West Texas

Abstract

One trematode, 2 cestode, 11 nematode, and 1 acanthocephalan species were collected from 66 bobcats, Felis rufus, in the Rolling Plains of West Texas between 1973 and 1977. These helminths included Alaria marcianae (5% of the bobcats infected), Taenia rileyi (91%), Mesocestoides corti (36%), Physaloptera praeputialis (88%), Cyathospirura chevreuxi (80%), Cylicospirura felineus (70%), Didelphonema longispiculatum (5%), Toxascaris leonina (91%), Toxocara mystax (17% ), Ancylostoma tubaeforme (58%), Pterygondermatites cahirensis (3%), Vogeloides felis (80%), Metathelazia californica (73%), Capillaria aerophila (3%), and Oncicola canis (14%). Scarring of the aorta due to Spirocerca lupi was observed in 35% of these animals. All hosts were infected with from 2 to 11 helminth species (x = 7.4 species). Simpson's index for all helminth species was low (0.10) indicating a lack of dominance of particular species in the helminth population of this host. Comparison of the helminth fauna of bobcats in West Texas with those of 4 other geographic areas in North America using Sorenson's index of similarity indicated a basic dissimilarity in helminth faunas of bobcats in different regions. Associations between the more prevalent helminth species were determined using frequency of occurrence and mean levels of infections. Significant relationships were noted in the frequency of occurrence of 8 pairs of helminth species. Cole's coefficient of association indicated a positive association between these species. Analysis of mean infection levels indicated significant relationships between 6 pairs of helminth species. A clumped distribution was indicated among the several species of spirurid nematodes occurring in the bobcat. These associations are explained in terms of the food habits (intermediate and paratenic hosts) and age of the host. Comparison of helminth species with the sex of the host based on frequency of occurrence indicated males were significantly more often infected with C. felineus and M. californica. Comparison of mean levels of infection indicated males had significantly higher levels of infection with C. chevreuxi, V. felis, and T. rileyi. Helminth parasitism has been sporadically examined in the bobcat, Felis rufus, from various localities in North America (Rollings, 1945; Pollack, 1949; Progulske, 1952; Miller and Harkema, 1968; Little et al., 1971). This host is distributed through widely varying habitats in the United States and Canada. It has recently become an economically important furbearer and is the only wild felid likely to remain in any abundance in Texas (Russell, 1971) and probably most of the United States. The present study was initiated in order to better understand the nature, prevalence, and intensity of helminth parasitism and to elucidate certain ecological relationships of parasitism including concentration of dominance, Received for publication 3 June 1977. * Department of Range and Wildlife Management, Texas Tech University, Lubbock, Texas 79409. Present address: Department of Forest Zoology, College of Environmental Science and Forestry, State University of New York, Syracuse, New York 13210. t Department of Pathology, Division of Comparative Pathology, Texas Tech University Health Sciences Centers, Lubbock, Texas 79409. similarity of helminth faunas between different geographic areas, and the nature of distributions of aggregations of helminth species in this host. MATERIALS AND METHODS Sixty-six bobcats were collected in the Rolling Plains of Texas in King, Knox, and Dickens counties between December 1973 and January 1977. The study area is characterized by gently rolling plains dominated by honey mesquite, Prosopis glandulosa, and native grasses intermingled with vast erosion beds of very uneven topography (breaks) with redberry juniper, Juniperus pinchotii, native grasses, and cacti as the predominant vegetation. Although interspersed with some land suitable for dryland farming, the area is principally utilized as rangeland. The majority of bobcats were obtained as carcasses from fur trappers. Body weights, measurements, and age determinations were obtained from 63 hosts prior to skinning. Usually, viscera were frozen in the field and later examined in the laboratory. The stomach of each animal was examined for prey remains, the results of which will be reported elsewhere (Stone and Pence, in preparation). Musculature and subcutaneous tissues were examined for filariids and a 2-cm square portion of diaphragm from each host was viewed microscopically in a muscle press for Trichinella