2009 SOUTHEASTERN NATURALIST 8(1):167–174
External Parasites of Neotoma magister Baird (Allegheny
Woodrat) in the Cumberland Mountains and Plateau,
Tennessee
William T. Parker1, Reid R. Gerhardt2, Lisa I. Muller1,*,
Nathan D. Caldwell3, Steven B. Castleberry4, and W. Mark Ford5
Abstract - We examined external parasites of Neotoma magister (Allegheny Woodrat)
from the Royal Blue Wildlife Management Area in the Cumberland Mountains
and Big South Fork National River and Recreation Area on the Cumberland Plateau
of Tennessee from November 2003 to August 2005. Typically associated with rocky
habitats such as clifflines and cave entrances, the Allegheny Woodrat is considered
a species of concern in Tennessee. We found external parasites on 26 out of 40 Allegheny
Woodrats (prevalence = 65%), including 2 Epitedia cavernicola Traub
(woodrat fleas—from 2 separate woodrats; prevalence = 5%), 63 Orchopeas pennsylvanicus
Baker (woodrat fleas—collected on all 26; prevalence = 65%, intensity
= 2.4/woodrat), and 5 Ixodes woodi Bishopp (Woodrat Ticks—collected from 1
woodrat; prevalence = 2.5%). Our collection represents a state record for Woodrat
Ticks in Tennessee. The external parasites collected from Allegheny Woodrats in
east Tennessee were considered woodrat-specific parasites and exhibited low species
diversity.
Introduction
Neotoma magister Baird (Allegheny Woodrat) is a medium-sized rodent
that dens and forages in and around rock habitats such as cliffl ines, colluvial
boulderfields, and cave entrances, and occasionally uses abandoned human
structures. Historically, Allegheny Woodrats ranged throughout the Appalachian
Mountains (Castleberry et al. 2006). Allegheny Woodrats have been
extirpated from New York and Connecticut, and have declined in the northern
and western parts of their range (Balcom and Yahner 1996, Castleberry
et al. 2006). Allegheny Woodrats appear to be more common in the central
and southern parts of their distribution (Castleberry et al. 2006). The Allegheny
Woodrat is considered a species deemed in need of management in
Tennessee (Tennessee Wildlife Resources Agency 2005). The rank in Tennessee
may be due to the general lack of information on population status in
the southern extent of the range. The decline of the Allegheny Woodrat has
1Department of Forestry, Wildlife, and Fisheries, University of Tennessee, 274 Ellington
Hall, Knoxville, TN 37996. 2Department of Entomology, University of Tennessee,
230 Ellington Hall, Knoxville, TN 37996. 3Department of Entomology, North
Carolina State University, 2301 Gardner Hall, Raleigh, NC 27695. 4Warnell School
of Forestry and Natural Resources, University of Georgia, Athens, GA 30602. 5US
Department of Agriculture Forest Service Northern Research Station, Parsons, WV.
*Corresponding author - lmuller@utk.edu.
168 Southeastern Naturalist Vol. 8, No. 1
been attributed to several factors including parasitism, predation, reduced
food availability, and loss of habitat due to land-use change (Castleberry et
al. 2006).
Several studies have documented the fl ea and tick fauna associated
with woodrats in the southeastern United States. Most early research was
conducted when Allegheny Woodrats were considered a subspecies of N.
fl oridana Ord (Eastern Woodrat). Subspecific status was recognized until
Hayes (1990) evaluated morphological and genetic characteristics suggesting
Allegheny Woodrat should be considered a separate species. However,
fl ea and tick species have been reported from Allegheny Woodrats in Indiana
(Cudmore 1986, originally reported as Eastern Woodrat) and West Virginia
(Castelberry et al. 2003), and reported from Eastern Woodrats in Georgia
(Durden et al. 1997), Mississippi (Clark and Durden 2002), South Carolina
(Durden et al. 1997, 1999), and Tennessee (Durden and Kollars 1997).
Orchopeas pennsylvanicus Baker and Epitedia cavernicola Traub have been
reported as host-specific fl eas of Neotoma species in the southeast United
States (Castelberry et al. 2003; Durden et al. 1997; Lewis 1974, 1975).
However, most ticks reported from Neotoma in the Southeast have been considered
generalist species (Castleberry et al. 2003; Clark and Durden 2002;
Cudmore 1986; Durden et al. 1997, 2000).
Allegheny Woodrats may have a higher degree of fl ea-host specificity
compared to Eastern Woodrats due to their specific habitat requirements
involving rocky areas (Castleberry et al. 2003). Allegheny Woodrats also
might have less contact with other small mammals, reducing the chance
of transmission of generalist parasites. In contrast, Eastern Woodrats build
large stick nests, which harbor other rodents that may facilitate transfer of
fl eas (Castleberry et al. 2003). Fleas often choose specific hosts that build
nests (Benton 1980). After a blood meal, fl eas lay their eggs on the host,
and the eggs eventually fall into the nest. After the eggs mature, the newly
emerged fl eas can infest the host and offspring in the nest (Benton 1980).
This adaptation results in a fl ea-host specificity.
Our goal was to determine the external parasitic species infesting Allegheny
Woodrats in the Cumberland Mountains and Plateau area of eastern
Tennessee. This area occurs in the southern end of the range for Allegheny
Woodrats. Although the ranges of Allegheny Woodrats and Eastern Woodrats
do not overlap, the available habitat used by both species is similar.
Therefore, we were also interested in comparing external parasites of Allegheny
Woodrats in Tennessee to those of Allegheny Woodrats in more
northern areas and to Eastern Woodrats.
Study Areas
We set traps for Allegheny Woodrats in the Royal Blue Wildlife Management
Area (RBWMA), located in the Cumberland Mountains and
2009 W.T. Parker et al. 169
comprised of 20,235 ha in Scott and Campbell counties, TN (36°20'N,
84°17'W) and the Big South Fork National River and Recreation Area
(BSFNRRA), located on the Cumberland Plateau along the Tennessee and
Kentucky border (36°29'N, 84°41'W). Both sites were located in the Appalachian
Highlands Physiographic Division (Fenneman 1916, Parker 2006).
We trapped in the Tennessee portion of BSFNRRA within Fentress, Scott,
Morgan, and Pickett counties.
Royal Blue WMA is dominated by mixed mesophytic forest, with
openings occurring on less than 3% of the landscape (Tennessee Wildlife
Resources Agency 2000). The BSFNRRA contains more mixed oak types
than RBWMA, though pockets of mixed mesophytic forest are present in
BSFNRRA as well (National Park Service 2005). The climate of both sites
is humid with mild winters and warm-to-hot summers. We located trapping
sites along rock bluffs, boulderfields, and abandoned human structures with
current or recent historic woodrat “sign” such as food caches, communal
latrines, and middens (Castleberry et al. 2006).
Methods
Trapping procedures
We live-trapped Allegheny Woodrats at 19 sites on RBWMA and
BSFNRRA between November 2003 and August 2005. The University
of Tennessee Institutional Animal Care and Use Committee approved all
trapping and animal procedures (UT-IACUC 1200). We placed Tomahawk
live traps (40.6 x 12.7 x 12.7 cm [16 x 5 x 5 in]; TL201 Tomahawk Live
Trap, Tomahawk, WI) at 10-m intervals along the base of the rock bluffs
and along the perimeter of boulder structures. We also placed traps within
abandoned vehicles and buildings and set them at 10-m intervals along
the perimeter of the structures. We baited live traps with sliced apples and
black oil sunflower seeds. We used cotton or polyester batting as bedding
material in all traps.
We trapped each site once during winter (November to March) and summer
(April to August). We set approximately 10 to 20 Tomahawk live traps
at each site depending on the extent and size of the emergent rock, cliffl ine,
or human structures. We set traps and checked them in the morning for 2
to 3 consecutive days. Most traps were checked between 7:00–10:00 am;
however, on occasion, workup of woodrats delayed checking traps until
12:00–1:00 pm.
Parasite collection and identification
We restrained captured woodrats in a cloth bag by scruffing the fur along
the neck and administering isofl urane via nose cone inhalation (Parker et
al. 2008). While woodrats were immobilized, we collected external parasites
using forceps. We combed the fur back, and all visible parasites were
170 Southeastern Naturalist Vol. 8, No. 1
collected and stored in labeled vials containing 70% ethanol (Castleberry et
al. 2003, Durden et al. 2004). The catch bag and bedding were also checked
for parasites. If a woodrat was caught in the trap, then the bedding was replaced
before the next trapping session.
We mounted fl ea specimens on slides using saline mounting solution and
identified them using a microscope. We placed larger external parasites, i.e.,
ticks, in petri dishes and identified them using a dissecting microscope. We
followed Benton (1983), Fox (1940), and Keirans and Litwak (1989) for
specimen identification. We calculated mean prevalence as percentage of
individuals infested and the mean intensity as the mean number of ectoparasites
per infested host animal.
Results
All parasites were collected directly from the woodrats or the catch bag.
We collected 63 fl eas and 5 ticks from 26 out of the 40 Allegheny Woodrats
trapped (prevalence of external parasites = 65%) during 1031 trap nights.
We deposited voucher specimens with the University of Tennessee Insect
Museum. Fourteen woodrats did not have any visible fl eas or ticks. Except
for 2 female woodrat fl eas, all fl eas were O. pennsylvanicus (18 males, 43
females). We collected the woodrat fl eas on 2 December 2003 in BSFNRRA
and 8 December 2004 in RBWMA (prevalence = 5 %). We collected the O.
pennsylvanicus at all sites during both seasons, and intensity was 2.4 fl eas/
woodrat (prevalence = 65%). We collected all 5 ticks from a single woodrat
trapped on 25 November 2003 at BSFNRRA at a steep bluff with many
shrubs and pines (prevalence = 2.5%). The ticks were female and nymphal
I. woodi (2 adult, 3 nymph).
Discussion
Orchopeas pennsylvanicus and E. cavernicola are host-specific fl eas
common to eastern and western woodrat species (e.g., Neotoma albigula
Hartley [White-throated Woodrat], Neotoma cinerea Ord [Bushy-tailed
Woodrat], Neotoma fuscipes Baird [Dusky-footed Woodrat]; Durden et al.
1997). Our fl ea collections from Allegheny Woodrats were similar to those
documented by Castleberry et al. (2003) in West Virginia, where there was
100% prevalence of O. pennsylvanicus in woodrats, whereas only one E.
cavernicola was documented. Cudmore (1986) also reported O. pennsylvanicus
(originally reported as O. sexdentatus) as the predominant fl ea and
E. cavernicola as a common fl ea infesting Allegheny Woodrats in Indiana;
however, he also found 2 other more general fl eas on the woodrats. Flea species
found on Eastern Woodrats have been considered more wide-ranging in
their host preference (Clark and Durden 2002; Durden et al. 1997, 2000).
The one tick we found, I. woodi, was considered a host-specific tick of
eastern and western woodrats (Durden et al. 1997). However, I. woodi also
2009 W.T. Parker et al. 171
has been reported from other mammalian species and therefore may not be
as host-specific as previously assumed (Allan 2001). Durden and Kollars
(1992) hypothesized that I. woodi could occur in Tennessee, but it had not
been previously reported. Reeves et al. (2007) reported Ixodes spp. on Allegheny
Woodrats in Blount County, TN, but there was no indication of the
species. Therefore, this is the first report of I. woodi in Tennessee.
Ixodes woodi was collected from Allegheny Woodrats in Indiana (Cudmore
1986), but, the most common tick was Dermacentor variabilis Say
(American Dog tick). Castleberry et al. (2003) documented one tick species,
Ixodes angustus Neumann (Squirrel Tick), when collecting parasites from
Allegheny Woodrats in West Virginia. Studies of Eastern Woodrats in the
Southeast have all shown mostly generalist ticks present (Clark and Durden
2002; Durden et al. 1997, 2000).
Durden et al. (1997) suggested eastern woodrats have had less time to
evolve with specific ectoparasites. Woodrats apparently evolved in western
North America and have more recently colonized eastern North America.
As the woodrats dispersed eastward, some of the ectoparasites may have
not adapted to eastern climate. Therefore, eastern woodrats (including Allegheny
Woodrat and Eastern Woodrat) may have lower diversity than their
western counterparts. Of the 6 species and subspecies of eastern and western,
woodrat-specific ectoparasites described by Durden et al. (1997), we
found 3 of these in the Allegheny Woodrats of Tennessee.
Eastern Woodrats use a more diverse, wide-ranging habitat than Allegheny
Woodrats, which prefer rocky areas (Whitaker and Hamilton 1998).
Castleberry et al. (2003) suggested that Allegheny Woodrats might have a
higher degree of host-specific fl eas compared to Eastern Woodrats due to
their requirement for rock bluffs and assumed limited interaction with other
mammals. A companion study found high numbers of Peromyscus spp. in
the same areas of RBWMA and BSFNRRA where we trapped for woodrats
(C. Hedio and W.T. Parker, University of Tennessee, Knoxville, TN, unpubl.
report). Even with the high numbers of Peromyscus spp. in the rocky areas,
the fl eas found on Allegheny Woodrats were all considered to be specific to
woodrats. However, the Peromyscus spp. and other trapped species were not
checked for parasites.
Interestingly, fleas found on Allegheny Woodrats in West Virginia
(Castleberry et al. 2003) and our study showed more host specificity than
those in Indiana (Cudmore 1986). Perhaps future work should examine
whether the limestone escarpments near the Ohio River where Allegheny
Woodrats occur in Indiana (reviewed in Castleberry et al. 2006) have
favored ectoparasite diversity. The Indiana site was located in the Interior
Plains Physiographic Division (Fenneman 1916). In contrast, the
Allegheny Woodrats in West Virginia and Tennessee both occurred in
the Appalachian Highlands Physiographic Division of the Appalachian
Mountains (Fenneman 1916).
172 Southeastern Naturalist Vol. 8, No. 1
Conclusion
External parasites of Allegheny Woodrats in Tennessee were all considered
woodrat-specific. This finding is in contrast to ectoparasites
found in Eastern Woodrats, which tend to be generalists that colonize
multiple host species (Clark and Durden 2002; Durden et al. 1997, 2000).
The diversity we found in Tennessee was similar to Allegheny Woodrats
in West Virginia, which also were studied in the Appalachian Highlands
Physiographic Division (Castleberry et al. 2003), but was less diverse
than that observed by Cudmore (1986) in Indiana in the Interior Plains
Physiographic Division. Tennessee has great diversity of ticks (Durden
and Kollars 1992) and fleas including several species of boreal fleas
specific to the Appalachian Mountain area (Durden and Kollars 1997).
Therefore, the lack of diversity in fleas and ticks on the Allegheny Woodrats
in Tennessee is noteworthy.
However, we probably did not collect all external parasites with our
sampling design. We were not specifically looking for mites. Evaluating
mite diversity may enhance our understanding of woodrat host specificity
given the high number of species found on Eastern Woodrats (Durden
et al. 1997). There seems to be greater ectoparasite diversity in Eastern
Woodrats, especially when you consider mites (Durden et al. 1997).
Future studies should compare ectoparasites of Eastern and Allegheny
Woodrats to the surrounding mammals in the Appalachian Highlands.
Acknowledgments
We thank the Tennessee Department of Health, Tennessee Valley Authority, the
National Park Service - Big South Fork National River and Recreation Area (Appalachian
CESU), and the Department of Forestry, Wildlife, and Fisheries for funding
that made this project possible. We would also like to thank Carrie Hedio Salyers,
Lauren George, Kristen Parker, and Pete Wyatt for their help locating and trapping
animals and collecting samples in the field. We thank David Paulsen for help with
ectoparasite identification.
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