Patterns of Infestation by AdultDermacentor variabilis(Acari: Ixodidae) in a Mark-Recapture Study of Raccoons (Mammalia: Carnivora) and Virginia Opossums (Mammalia: Didelphimorphia) in Tennessee

Abstract

A mark-recapture study of raccoons (Procyon lotor L.) and Virginia opossums (Didelphis virginiana Kerr) was conducted from February 1991 through April 1994 to determine host interactions with adult Dermacentor variabilis Say. We captured 1,293 raccoons and Virginia opossums during the 3-yr study (140 individual raccoons and 160 individual Virginia opossums) with 1,895 adult D. variabilis collected. Raccoons had a significantly higher mean intensity and higher prevalence of adult ticks than Virginia opossums (Mann-Whitney Z = 6.15, chi 2 = 51.9, P < 0.001). Mean intensity follows Margolis et al. (1982) as being the mean number of parasite species per infected host. Prevalence follows Margolis et al. (1982) as being the number of individuals of the host species infected with a parasite species divided by the number of hosts examined. The time required for a higher prevalence and mean intensity of ticks to occur on raccoons than Virginia opossums was < 7 d. No significant differences occurred between the mean intensity or prevalence of D. variabilis between sexes or among age classes of raccoons. Significant differences in prevalence and mean intensity of ticks occurred between sexes and among age classes of Virginia opposums. Infestation increased by 0.64 ticks per day on Virginia opossums and 1.77/d on raccoons during the first 7 d. The base host finding rate (ticks per host per day) of adult D. variabilis on Virginia opossums was 0.064 and 0.053 on raccoons. Tick interactions with hosts are quantified and may reflect behavioral differences between sexes and among age groups intraspecifically, and host preferences of adult D. variabilis interspecifically.

Prevalence of And Risk Factors for Canine Tick Infestation in The United States, 2002–2004

“…Observed variation in monthly prevalence of tick infestation agreed with previous reports on seasonal activity of ticks in different parts of the country (Anderson and Magnarelli 1980, Barker et al 2004, Carey et al 1980, Kardatzke et al1992, Koch 1982, Kollars and Ladine 1999, Stafford and Magnarelli 1993. For example, D. variabilis parasitized a significantly higher percentage of raccoons and opossums in Tennessee from April through September than from October through March (Kollars and Ladine 1999).…”

“…For example, D. variabilis parasitized a significantly higher percentage of raccoons and opossums in Tennessee from April through September than from October through March (Kollars and Ladine 1999). In the present study, tick prevalence was highest in Tennessee from April through August.…”

“…Several studies have compared the relative abundance of ticks among specific habitats, terrains, or residential sites (Carey et al 1980, Stafford et al 1998, Stafford and Magnarelli 1993, or reported tick prevalence on domestic and wild mammals, or characterized the species of ticks found naturally attached to a wide range of hosts including humans (Anderson and Magnarelli 1980, Barker et al 2004, Carey et al 1980, Falco and Fish 1988, Felz et al 1996, Foley et al 1999, Goddard 1989, Greiner et al 1984, Hall et al 1991, Koch 1982, Kollars and Ladine 1999. These studies, however, covered small geographic areas and used a wide variety of techniques to measure tick abundance.…”

“…Mapping distribution based on direct field observations, however, is time consuming and requires large-scale organization (Daniel and Dusbabek 1994). Limited areas are studied using techniques such as flagging, walking, trapping, and collecting from several wild and domestic hosts including humans, to report tick abundance (Anderson and Magnarelli 1980, Barker et al 2004, Carey et al 1980, Falco and Fish 1988, Felz et al 1996, Foley et al 1999, Goddard 1989, Greiner et al 1984, Hall et al 1991, Kollars and Ladine 1999, Stafford et al 1998, Koch 1982, Stafford and Magnarelli 1993. Because of the diversity in measurement techniques, the findings from published reports cannot always be directly compared across the nation.…”

Spotted Fever Group <I>Rickettsia</I> in <I>Dermacentor variabilis</I> (Acari: Ixodidae) Infesting Raccoons (Carnivora: Procyonidae) and Opossums (Marsupialia: Didelphimorphidae) in Tennessee

“…However, opossums may become the principal host when its populations are dense (Zimmerman et al 1988). In Tennessee, raccoons become infested 2.77 times more quickly by adult D. variabilis than do opossums (Kollars and Ladine 1999). In the current study we found that opossums and raccoon serve as hosts to spotted fever group Rickettsia infected adult D. variabilis in western Tennessee.…”