Ecological aspects of small strongylids in the Paraíba Valley Region, State of São Paulo, Brazil

Abstract

Post-mortem studies were conducted on twenty equids (16 horses and four mules) of the Paraíba Valley, during a period of twelve years (1988 to 2000) in order to establish the ecological descriptors of the different species of small strongylids (Subfamily Cyathostominae, Tribe Cyathostominea). Samples of 10% of total gastrointestinal content was examined and a total of 13,832 of Cyathostominea were obtained with a prevalence of 100%. The most prevalent and abundant species were Cylicocyclus nassatus (100%), Cylicostephanus longibursatus and Cylicostephanus goldi (95%). The population of Cyathotominea showed an average Dispersion Index (DI) of 49.03 and an average Green index (GI) of 0.226. The parasitic community had average diversity of 1.79, calculated by Shannon-Wiener' Index, and 0.77 by Simpson's Index of Diversity. The evenness (Pielou's Index) presented an average of 0.28.The intensity of infection had a positive correlation with the parasite richness (P<0,05) and the diversity (P<0,01). Specimens of C. nassatus showed preference for the ventral colon (P<0.01), Cyathostomum coronatus for the caecum (P<0.01), C. longibursatus and C. goldi a preference for both the ventral colon and the dorsal colon (P<0.01).