| Summary |
The seasonal dynamics of parasite populations in Sigmodon hispidus were evaluated. Cotton rats were collected each month during a two-year period (June 1970 through March 1972) in a grassy field in Greenville, North Carolina. Of 130 cotton rats autopsied, 114 (87.7%), were infected with one or more species of helminths. A total of 2,208 parasites representing two phyla and five species were recovered. These were Raillietlna bakeri, Hymenolepis diminuta, larval Taenia taeniaeformis, Mastophorus muris ascaroides, and Longlstrlata adunca. Identification of the larval taenlaeformis was supported by the infection of a laboratory cat with stroblicerci from the liver of cotton rats and subsequent recovery of the adult worm. A seasonal variation in incidence of Infection with individual species of parasites was observed, with high infections in summer and winter and low in spring and fall for each species. Differences were observed in degree of infection between male and female hosts. Male cotton rats had greater infections than females for all species of helminths, although the differences were not statistically significant (P[less-than].05) except for L. adunca. Spring is the time of heavy recruitment of parasites by the cotton rat host and seasonal variation in numbers of helminths may be related to the availability of intermediate and definitive hosts. High temperature and low rainfall in summer may retard development of eggs or intermediate hosts, accounting for a decline in infection during fall. Behavior of the cotton rat may account for heavy infections with L. adunca, a parasite without an intermediate host. Age of the host appeared to be related to the number and kind of parasites present. Older rats had more and a greater variety of parasites than did younger rats. Pregnant female rats had infections similar to non-pregnant female rats. The effect of host diet, climate, daily temperature and rainfall differences were evaluated. |
