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Examination of extensive Dermacentor Koch, 1844 holdings stored in several major tick collections allowed us to re-evaluate the taxonomic content of Dermacentor everestianus Hirst, 1926 and redescribe all of its parasitic stages in detail for the first time. Examination of the type specimens of Dermacentor abaensis Teng, 1963 , a species treated as valid by most workers, and Dermacentor birulai Olenev, 1927 , a species some recent authors considered as valid, led us to the conclusion that they are junior synonyms of D. everestianus. The relation of D. everestianus with some other species in the genus is questionable and warrants further studies. From possibly sympatric Dermacentor species, the adults of D. everestianus can be distinguished by the following combination of characters: intensive ivory colored ornamentation of conscutum and scutum, absence of brown patches on lateral fields of conscutum in the male, long and narrow dorsal prolongation of spiracular plates, short cornua, short dorsal spur on trochanter I, and absence of large ventral spur on distal ends of genua and tibiae II-IV. Nymphs of D. everestianus can be distinguished by numerous setae on alloscutum (>48 pairs), large spiracular plates with their longitudinal diameter exceeding that of sclerotized ring around anal valves, moderate lateral projections of basis capituli with blunt apices situated slightly posterior to the midlength of basis capituli dorsally, relatively large auriculae, relatively short, narrowly rounded at apices spurs on coxae I with internal spur being shorter than external and moderate triangular spur on coxae IV; while larvae can surprisingly easily be distinguished from those of other species found in the region by greatly elongated posterior portion of scutum where eyes are situated just posterior to the midlength of scutum. So far, D. everestianus is found only in China and Nepal, where the adults were collected from domestic and wild ungulates while the immature stages were recorded from lagomorphs and rodents.

Abstract :  A new tick species belonging to the African subgenus Afrixodes Morel, 1966 of the genus Ixodes Latreille, 1795, namely, Ixodes (Afrixodes) microgalei n. sp., is described. Females of this species are most similar to those of Ixodes colasbelcouri Arthur, 1957 and Ixodes nesomys Uilenberg & Hoogstraal, 1969. The female of the new species can easily be differentiated from I. colasbelcouri by a short spur on coxae IV, and from I. nesomys by longer spurs on coxae I and large punctations on its scutum. Ixodes microgalei is known only from the eastern humid forest of Madagascar, specifically in the Province of Antananarivo, where its females have been collected from several species of shrew tenrecs (Afrosoricida, Tenrecidae), namely, Microgale dobsoni Thomas, Microgale parvula Grandidier, and Microgale soricoides Jenkins.

A new tick species belonging to the African subgenus Afrixodes Morel, 1966, namely, Ixodes ( Afrixodes ) fynbosensis n. sp., is described. The female of I. fynbosensis is easily differentiated from the other African Ixodes species by a large, tapering triangular ventrolateral spur on palpal segment I. Nymph and larva of I. fynbosensis can be distinguished from those of other members of Afrixodes by a combination of the following characters: pointed hypostome, long auriculae, long and acute ventrolateral projections of basis capituli of nymph, only 2 pairs of central dorsal setae, and a straight posterior margin of scutum of the larva. Cytochrome oxidase I mtDNA sequence comparisons between I. fynbosensis and 10 other Ixodes Latreille, 1795, species support the recognition of this taxon as genetically distinct (>13% corrected sequence divergences separate it from the remainder of the 10 recognized species used in this study), and preliminary phylogenetic analyses reveal that this taxon is most closely related to the southern African Ixodes pilosus Koch, 1844, and Ixodes rubicundus Neumann, 1904. Ixodes fynbosensis is known only from South Africa, where females have been collected from a domestic dog and a rodent, Rhabdomys pumilio (Sparrman), and nymphs and larvae have been collected from R. pumilio and unidentified shrews belonging to the Soricidae. Sequences generated for both nymphs and adult individuals were identical, confirming the correlation between the described life stages.

Ectoparasite and epifaunistic arthropod biodiversity and infestation parameters were compared between 2 sympatric small rodent species, the cotton mouse (Peromyscus gossypinus (Le Conte)) and golden mouse (Ochrotomys nuttalli (Harlan)), in southern Georgia from 1992 to 2003. Because the cotton mouse is known to be a reservoir of more vector-borne zoonotic pathogens than the golden mouse, we hypothesized that it would be parasitized by more ectoparasites that are known to be vectors of these pathogens. Cotton mice (n = 202) were parasitized by 19 species of arthropods, whereas golden mice (n = 46) were parasitized by 12 species. Eleven species of arthropods were recovered from both host species, whereas 7 were recorded only from cotton mice, and 1 species only from golden mice. Infestation prevalences (percent of mice parasitized) were significantly higher for 1 species of arthropod (the tropical rat mite Ornithonyssus bacoti (Hirst)) infesting cotton mice and for 4 species (the flea Peromyscopsylla scotti Fox and the mites Glycyphagus hypudaei Koch, Androlaelaps casalis (Berlese), and Androlaelaps fahrenholzi (Berlese)) infesting golden mice. Mean intensities (mean per infested mouse) were significantly higher for 2 species (the flea Orchopeas leucopus (Baker) and the blacklegged tick Ixodes scapularis Say) infesting cotton mice and for 2 species (G. hypudaei and A. fahrenholzi) infesting golden mice. Ectoparasites that are known to be vectors of zoonotic pathogens were significantly more common on cotton mice than on golden mice. These ectoparasites included the rhopalopsyllid flea Polygenis gwyni (Fox), a vector of the agent of murine typhus; I. scapularis, the principal vector of the agents of Lyme borreliosis, human granulocytic ehrlichiosis, and human babesiosis; and O. bacoti, a laboratory vector of several zoonotic pathogens. However, 2 species of ixodid ticks that can transmit zoonotic pathogens were recovered from both host species. These were the American dog tick Dermacentor variabilis (Say), the principal vector of the agent of Rocky Mountain spotted fever in eastern North America, and Ixodes minor Neumann, an enzootic vector of the agent of Lyme borreliosis. Overall, the cotton mouse was parasitized by significantly more ectoparasites that are known to be vectors of zoonotic pathogens than was the golden mouse. These data support the hypothesis that the cotton mouse has greater epidemiological importance for zoonotic vector-borne pathogen transmission than does the golden mouse.

Fifty Borrelia isolates from ticks and rodents from several geographic regions of the southern United States were analyzed by genomic macrorestriction analysis. Significant genetic diversity was observed among them. These isolates segregated into 4 major clusters and 10 subclusters, which are correlated with the genospecies distribution. Nineteen pulsed-field gel electrophoresis (PFGE) types were recognized among the isolates. The genospecies Borrelia andersonii and Borrelia bissettii consisted of 5 and 2 subclusters, respectively. Two subclusters comprised the Borrelia burgdorferi sensu stricto (s. s.) strains. These results indicated that PFGE is a suitable molecular typing method for B. burgdorferi at both the genospecies and strain levels. Seventeen representative isolates from different PFGE groups were analyzed by restriction fragment length polymorphism (RFLP) and sequence analysis of flaB. Twenty-three AluI, 3 CelII, and 11 DdeI RFLP patterns were found among strains from the B. burgdorferi sensu lato (s. l.) complex and the relapsing fever borreliae complex. Three genospecies in the B. burgdorferi s. l. complex and 1 species in the relapsing fever borreliae complex were recognized. Phylogenetic analysis based on nucleotide sequences of flaB indicated that all the Borrelia strains analyzed here could be divided into 2 parts, i.e., B. burgdorferi s. l. complex and the relapsing fever borreliae complex. The flaB appears to be a useful target gene to screen and identify strains from both B. burgdorferi s. l. and relapsing fever borreliae complexes.

Gray squirrels, Sciurus carolinensis, were livetrapped in 2 different habitat types, woodland (67 squirrels) and parkland (53 squirrels), in southeastern Georgia. Ectoparasites were recovered from anesthetized squirrels and compared between hosts from the 2 habitats. Because of the absence of low vegetation in parkland habitats, it was hypothesized that the ectoparasite fauna, especially ticks and chiggers, would be more diverse on woodland squirrels. The results were generally in agreement with this hypothesis. Seventeen species of ectoparasites were recovered from woodland squirrels, compared with 6 species from parkland squirrels. Five species of ticks and 3 species of chiggers parasitized the woodland squirrels compared with no ticks or chiggers on the parkland squirrels. Significantly higher infestation prevalences were recorded on woodland compared with parkland squirrels for the flea Orchopeas howardi, the tick Amblyomma americanum, and the mesostigmatid mite Androlaelaps fahrenholzi. The mean intensity for O. howardi also was significantly higher on woodland than on parkland squirrels. Because a new strain of Bartonella sp. was isolated recently from S. carolinensis in Georgia, selected ectoparasites from this study were screened for bartonellae by polymerase chain reaction (PCR). Some of the fleas and lice, but none of the mites tested, were PCR positive, suggesting that fleas, or lice, or both, might be vectors of bartonellae between squirrels. Six distinct strains of Bartonella sp. were detected, 2 in fleas and 4 in lice.

Partial mitochondrial 16S ribosomal ribonucleic acid gene sequences in the ticks Carios capensis collected from black-footed albatross. Diomedea nigripes, colonies on Torishima Island, Japan (30 degrees 28'N, 140 degrees 18'E), were examined. The sequence was compared with those of C. capensis from Hawaii, South Carolina, and Texas. The sequences were all identical in ticks from Torishima and 2 from Hawaii. There were 2-3 transitions between the other Hawaiian and Texas ticks and Torishima specimens. Two transitions were also observed when compared with the ticks from South Carolina. The results suggest the possibility of gene flow between tick populations at each of the 2 geographic sites, which probably was accomplished by tick-infested migratory seabirds at their breeding sites. Sequence comparison analysis indicated that the C. capensis ticks are on the branch with C. marginatus and C. mexicanus ticks and not with Ornithodoros. This supports the revision suggested by Klompen and Oliver (1993).

A total of 237 rodents was collected in 4 regions of South Carolina from July 1994 through December 1995. Eight species were collected, including cotton mouse, hispid cotton rat, eastern woodrat, marsh rice rat, white-footed mouse, eastern harvest mouse, golden mouse, and black rat. Of the 1,514 ticks recovered from these hosts, Ixodes minor Neumann, including larvae, nymphs, and adults, was the most abundant species, representing 54% of the total. Only immature stages of other tick species were found, including larvae and nymphs of Dermacentor variabilis (Say), Amblyomma maculatum Koch, Ixodes affinis Neumann, and Ixodes scapularis Say. All 5 tick species parasitized cotton mice, cotton rats, and woodrats, which were the most important small mammal hosts for ticks at the localities studied. Rice rats were hosts of A. maculatum, D. variabilis, and L. minor. Amblyomma maculatum was more strongly associated with cotton rats than other rodent species. Ixodes scapularis was most strongly associated with cotton mice, and I. minor was more strongly associated with both woodrats and cotton mice than other species of rodents. Ixodes minor parasitized hosts in the Coastal Zone only, where among spirochete-infected hosts, it was present in significantly greater numbers than other ticks. Furthermore, I. minor was the only tick species that showed a statistically significant positive association with spirochetal infection in rodents. More I. affinis parasitized spirochete-infected hosts than I. scapularis, but fewer than I. minor. The findings discussed herein provide evidence that implicates I. minor as the possible primary enzootic vector of the Lyme disease spirochete Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt and Brenner in the Coastal Zone of South Carolina. They also indicate that the high level of B. burgdorferi infection in rodents from this region may be a function of the combined involvement of I. minor, I. affinis, and I. scapularis in the enzootic transmission of the spirochete.

From June 1993 through June 1996, 2,260 adult, 4,426 nymphal, and 2,178 larval lone star ticks Amblyomma americanum (L.) were collected in Missouri from vertebrate hosts and by dragging a cloth over vegetation. Prevalence, mean intensity, and relative abundance of each stage varied among hosts. The relative abundance of adult lone star ticks was highest on white-tailed deer, but this stage was also collected from raccoons, opossum, red fox, coyotes, and wild turkey. Nymphs were collected from gray squirrels, eastern cottontail rabbits, opossums, red fox, Carolina wren, and bobwhite quail, but the highest relative abundance occurred on wild turkey, white-tailed deer, and raccoons. Eastern cottontail rabbits, white-tailed deer, raccoons, and squirrels had the highest relative abundance of larval lone star ticks, but they were also found on opossums and wild turkey. The activity of adult lone star ticks was greatest from May through July. The activity for nymphs was highest from May through August, and for larvae, July through September.

Mist-netted birds were examined for ticks on Jekyll Island, Glynn Co., Georgia (32 bird species) in 1996-1998, and at Fort Morgan, Baldwin Co., Alabama (36 species) in 1998 during fall migration. Sixty-two (14.7%) of 423 birds from Jekyll Island and 22 (13.3%) of 165 birds from Fort Morgan were infested with ticks. The mean number of ticks per infested bird was 2.0 on Jekyll Island and 6.3 at Fort Morgan. Ten species of birds were infested with ticks on Jekyl1 Island where 87% of all ticks were recovered from 3 species: the common yellowthroat (Geothlypis trichas), gray catbird (Dumetella carolinensis), and northern waterthrush (Seiurus noveboracensis). Eight species of birds were infested with ticks at Fort Morgan where 83% of all ticks were recovered from 3 species: the brown thrasher (Toxostoma rufum), swamp sparrow (Melospiza georgiana), and common yellowthroat. Six species of ticks (Amblyomma americanum, Amblyomma maculatum, Haemaphysalis leporispalustris, Ixodes brunneus, Ixodes minor, and Ixodes scapularis) were recovered from the Georgia birds, whereas 3 species (A. maculatum, H. leporispalustris, and Ixodes dentatus) were recovered from the Alabama birds. Attempts to isolate Borrelia burgdorferi sensu stricto, the etiologic agent of Lyme borreliosis, from Ixodes spp. ticks recovered from birds were unsuccessful.

An internal transcribed spacer (ITS2) sequence between the 5.8S and 28S rRNA genes was used to estimate the phyletic relationships among Ixodes spp. tick vectors of Lyme disease-causing Borrelia spirochetes. Analysis indicates that Borrelia burgdorferi sensu lato species associated with Lyme disease are found mainly in ticks of the Ixodes ricinus species complex. Other closely related tick species are not known to transmit the Borrelia-that cause Lyme disease in humans, but they appear to have a specific association with other closely related Borrelia species. There is a high degree of concordance in the phylogenetics of Borrelia taxa and the phylogenetic relationships among Ixodes ticks.

A hamster was inoculated with the SI-1 strain of Borrelia burgdorferi and subsequently served as a host to larval Ixodes scapularis Say. Approximately 68% of the nymphs resulting from the fed larvae were infected. Nymphs from this group were fed on uninfected hamsters, and 3 of 4 males and 6 of 6 females became infected. The infected hamsters were allowed to mate with uninfected partners to test for venereal transmission. Six infected females were mated with 6 uninfected males, whereas 3 infected males were mated with 6 uninfected females. None of the uninfected hamsters became infected after mating. Two protocols were used to determine if transplacental transmission of B. burgdorferi occurred. One group included 6 nonpregnant infected females that were subsequently mated and became pregnant. Three of the females were allowed to carry to full term, whereas the other 3 were killed prior to parturition. All fetuses and offspring were negative for B. burgdorferi based on cultures and monoclonal antibody assays. Another group of 6 females was infected via tick bite after becoming pregnant; those females were allowed to carry fetuses to birth and all were negative. Attempts at contact transmission of B. burgdorferi from 2 infected females to 2 uninfected male and 2 uninfected female hamsters and from 2 infected males to 2 uninfected male and uninfected female hamsters via urine or feces failed.

Ticks and blood samples were collected from wild birds mist-netted on St. Catherine's Island, Georgia, and at the Wedge Plantation in coastal South Carolina in 1994 and 1995. Immature stages of 5 species of ixodid ticks were recovered from 10 of 148 (7%) birds belonging to 6 species in Georgia, whereas 6 ixodid species were recovered from 45 of 259 (17%) birds representing 10 avian species in South Carolina. Borrelia burgdorferi sensu lato was isolated from 27 of 120 (23%) screened ticks (Ixodes scapularis and Ixodes minor) recovered from South Carolina birds, but from none of 16 screened ticks removed from Georgia birds. This spirochete was also isolated from 1 of 97 (1%) birds in South Carolina. In 1995, neither eastern equine encephalitis (EEE) virus nor St. Louis encephalitis (SLE) virus was isolated from any of 218 bird sera screened, but serum neutralizing antibodies were found to EEE virus in 4 of 121 (3%) sera and to SLE virus in 2 of 121 (2%) sera from South Carolina. No antibody to either virus was detected in 51 avian sera screened from Georgia. Trypanosomes (probably Trypanosoma avium) were isolated from 1 of 51 (2%) birds from Georgia and from 13 of 97 (13%) birds from South Carolina. Our data suggest that some wild birds may be reservoir hosts for the Lyme disease spirochete and for encephalitis viruses in coastal Georgia and South Carolina and that migrating birds can disperse immature ticks infected with B. burgdorferi.

Ecdysteroids are the only hormones unequivocally identified thus far in ticks. We found a positive correlation between ecdysteroid concentration and vitellogenin synthesis in female Ixodes scapularis. Vitellogenin (Vg) synthetic activity was measured by an in vitro assay for Vg, involving incubations of the fat body with 35S-methionine and immunoprecipitation collected on a solid-phase matrix, protein A. Vitellogenin synthetic activity in the fat body was undetectable in unfed females but was detected after tick attachment to the host. Vitellogenin production in the fat body remained low from attachment until 2 days prior to detachment from the host. Vitellogenin synthesis in the fat body peaked 2 days after detachment and declined to a level 2-3 times above background from 6 days after dropping from the host through oviposition. A peak of ecdysteroids in females 6 days after attachment preceded an increasing rate of Vg synthesis, suggesting a positive correlation between these parameters. Ecdysone and 20-hydroxyecdysone, the 2 major ecdysteroids present during vitellogenesis, could not be detected in females prior to feeding or 2 days after attachment to the host; however, concentrations began to increase 4 days after attachment, peaked during rapid engorgement, and subsequently declined.

We collected ectoparasites from eastern woodrats, Neotoma floridana, from 3 sites in the southeastern United States: coastal South Carolina, southeast Georgia, and south-central Georgia. Twelve ectoparasite species were recovered from 47 woodrats in South Carolina (5 ticks, 5 mites, 2 fleas), 13 from 35 woodrats in south-central Georgia (1 tick, 10 mites, 2 fleas), and 4 from a small host sample (7) in southeast Georgia (2 ticks, 1 mite, 1 flea). New state records are established for the listrophorid mite Listrophorus neotomae from both Georgia and South Carolina, the myocoptid mite Myocoptes neotomae from Georgia, and the ceratophyllid flea Orchopeas sexdentatus pennsylvanicus from South Carolina. Different ectoparasites predominated on woodrats at each site with the tick Ixodes minor being the most commonly collected species in South Carolina, the American dog tick Dermacentor variabilis in southeast Georgia, and the chigger Euschoengastia peromysci in south-central Georgia. Most of the 17 species recovered are known to parasitize several species of mammals, especially rodents, and none of them are host specific to N. floridana. However, the fleas Epitedia cavernicola and Epitedia neotomae are host-specific ectoparasites of eastern woodrats in other parts of their range. Also, 1 species of tick, 2 mites, and 3 fleas parasitize eastern woodrats in addition to western woodrats. A similar lack of host specificity is apparent for the few previously documented collections of ectoparasites from eastern woodrats, including 1 detailed survey in Indiana. Conversely, Neotoma spp. woodrats inhabiting western North America are parasitized by a plethora of host-specific ectoparasites including 2 tick species, 5 mites (other than chiggers), 20 chiggers, 2 sucking lice, and 42 fleas. Recognizing that western biotas are typically more speciose than corresponding eastern biotas in North America, we further propose that because eastern woodrats are the most recent and eastern descendants of the ancestral Neotoma stock, (1) some ectoparasite species failed to accompany the eastern woodrat lineage in its eastward dispersals, and (2) there has been insufficient time for a diverse assemblage of ectoparasites to co-evolve with eastern woodrats.

A morphological study of the larval stage of the blacklegged tick, Ixodes scapularis, was conducted to further examine congruence between northern and southern morphotypes. Preliminary ANOVA revealed that 9 characters were not significantly different; thus 28 characters were used in analyses of a total of 8 groups of I. scapularis originally from Minnesota, Massachusetts, Maryland, Missouri, North Carolina, Georgia, F1 progeny of reciprocal crosses of ticks from Massachusetts and Georgia, and I. pacificus from California. Principal components (PC) analysis identified seven setal (sternal, preanal, 3 scutal, central, and marginal dorsal) and 3 nonsetal characters (interauricular distance, hypostome internal file, and coxa I internal spur) with positive static allometries. All Mahalanobis distances in canonical variate analyses (CVA) including and excluding I. pacificus and setal characters were significantly different. Scatterplots from PC and CVAs separated I. pacificus from all other groups in the first axis; the second function arranged groups in a pattern related to latitude. Unlike the results of previously reported nymphal analyses, no multivariate effect related to longitude was revealed; however, Missouri larvae had the shortest values for 2 setal and 9 nonsetal characters. As in nymphs, frequency polygons revealed an overlapping/continuous pattern, indicative of clinal geographic variation.

A new, unusual spirochete was cultured in Barbour-Stoenner-Kelly (BSK II) medium from the midgut and other tissues of the tick Ixodes dentatus. The tick was collected from leaf litter in an oak-pine wood lot in Bibb County approximately 7.2 km from Macon in central Georgia during February 1993. Characterization by indirect immunofluorescence using 5 murine monoclonal antibodies, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole spirochetal lysates, and by polymerase chain reaction assay for several known DNA target sequences indicates that the spirochete is Borrelia burgdorferi sensu lato. It is genetically different from the B-31 reference strain of B. burgdorferi sensu stricto that is typical of strains causing Lyme borreliosis in North America. Range of infectivity and pathogenesis of the Bibb County isolate (BC-1) are unknown but being investigated. The BC-1 strain is the first B. burgdorferi isolate from I. dentatus in the southeastern United States (I. dentatus is not the common vector for Lyme borreliosis in humans). Additionally, the collection site was approximately 322 km from the Atlantic coast, far distant from where most B. burgdorferi isolates have been obtained.

Lyme borreliosis (Lyme disease) is the most often reported arthropod transmitted disease in humans in the U.S.A. Although it has been reported from 43 states, cases are especially abundant in the mid-Atlantic and northeastern regions. Borrelia burgdorferi, the etiologic agent, is transmitted primarily by the western blacklegged tick (Ixodes pacificus) in far western North America, and by the blacklegged tick (Ixodes scapularis) in eastern North America. Although Lyme disease cases have been reported from southern states, some researchers doubt the presence of B. burgdorferi or of human Lyme disease in the south. However, new data show that B. burgdorferi is widely distributed in the south and that strains are genetically more varied than in the north. Moreover, B. burgdorferi enzootic cycles appear to be more complex and more tick species are identified as vectors of the spirochete in the southern states.

From 1990 through 1995, 913 ticks removed from 460 human patients in Georgia or South Carolina were identified and recorded. The majority of these specimens (758, 83.0%) were lone star ticks, Amblyomma americanum. One hundred and four (11.4%) American dog ticks Dermacentor variabilis, 36 (3.9%) blacklegged ticks Ixodes scapularis, 9 (1.0%) Gulf coast ticks Amblyomma maculatum, and 6 (0.7%) brown dog ticks Rhipicephalus sanguineus were also recovered. All active stages (larvae, nymphs, and adults) of A. americanum were represented, whereas nymphs and adults of D. variabilis and I. scapularis and only adults of A. maculatum and R. sanguineus were recorded. Compared with data published for other regions in the U.S.A., A. americanum was a much more prevalent parasite of humans in the current survey. Only 1 (3%) of the I. scapularis collected was a nymph. Because these tick species are vectors of zoonotic pathogens or cause tick paralysis in humans, the data have epidemiological significance.

Quantitative tick drag samples were taken at various times during the day and night from February through April 1994 on St. Catherines Island or on Sapelo Island, Georgia. For each month, there was no statistical difference between the numbers of adult blacklegged ticks, Ixodes scapularis, collected during any hour of daylight or darkness on St. Catherines Island, Adult I. scapularis also quested during both day and night on Sapelo Island, but on this island significantly more ticks were collected in 1 nocturnal sample during March. Nocturnal questing may partially explain why hosts that are principally nocturnal or that are active during both day and night are often heavily parasitized by adult I. scapularis. This observation could be epidemiologically important with respect to tickborne zoonoses such as Lyme disease and babesiosis.

This is the first report of natural infection by Borrelia burgdorferi in the cotton rat Sigmodon hispidus. Nine B. burgdorferi isolates were obtained from ear tissues, urinary bladders, or both, by culturing tissues in BSKII medium. The rat from which the SI-3 isolate was cultured was from the same site (Sapelo Island, Georgia) as an infected cotton mouse Peromyscus gossypinus and Ixodes scapularis tick reported previously. The 8 B. burgdorferi isolates from rats in Florida included 1 (AI-1) from Amelia Island, 1 (FD-1) from Faver-Dykes State Park, and 6 (MI-3 through MI-8) from Merritt Island. The distance between Sapelo Island and Merritt Island is approximately 400 km. All B. burgdorferi isolates were characterized by indirect immunofluorescence using monoclonal antibodies to OspA (H3TS, H5332) and OspB (H5TS, H6831), polymerase chain reaction detection of specific B. burgdorferi B-31 DNA target sequences (ospA, fla, and a random chromosomal sequence), and sodium dodecyl sulfate-polyacrylamide gel electrophoresis of spirochetal proteins. The phenotypic and genotypic characteristics of the isolates are discussed, as well as the probable importance of the cotton rat as a reservoir for B. burgdorferi in the southern United States.

The male of Amblyomma rotundatum is described for the first time, and the nymph and larva are redescribed. This tick is a parthenogenetically reproducing species parasitic on amphibians and reptiles in the warmer areas of the New World. Attempts to mate male and female A. rotundatum under laboratory conditions were unsuccessful.

Preserved museum specimens of 13 lizard and 3 snake species common in the southeastern U.S.A. were examined for immature Ixodes scapularis Say ticks. Five Eumeces and 4 Ophisaurus lizard species yielded an infestation prevalence of 17.8% for species of Eumeces and 29.0% for species of Ophisaurus. Mean intensity of larvae and nymphs was 7.1 and 2.7, respectively, for species of Eumeces, and 6.3 and 1.4, respectively, for species of Ophisaurus. Collection dates of the lizards ranged from January through December, but most were collected from March through October. The maximum number of immatures found on a single specimen was 193 larvae and 11 nymphs on a specimen of Eumeces and 75 larvae and 7 nymphs on a specimen of Ophisaurus. For species of Eumeces, 75.2% of all nymphs observed were attached in the shoulder area. Larvae were most abundant on the rear legs (53.3%), followed by the front legs (26.3%) and shoulders (12.9%). Larvae and nymphs on species of Ophisaurus were found almost exclusively in the lateral groove area (84.0% and 94.4%, respectively). Three other lizard species (Anolis carolinensis, Sceloporus undulatus, Scincella lateralis) had only a few ticks or none. A fourth species, Cnemidophorus sexlineatus, hosted a total of 3 larvae on 3 specimens (infestation prevalence, 10.7%). Three snake species (Diadophis punctatus, Virginia striatula, Crotalus adamanteus) had none.

The parthenogenetic tick Amblyomma rotundatum, a Central and South American species, has become established in southern Florida. The date of introduction is unknown, but it is suspected to be either during the 1930s, when 1 of its natural hosts, the giant or marine toad, Bufo marinus, was introduced to southern Florida as a potential biological control of pest beetles in sugar cane fields, or between 1955 and 1964 when specimens of B. marinus were accidentally or deliberately released in the greater Miami area. Several museum specimens of this toad collected in the Miami area 25 April 1979 had nymphal and adult A. rotundatum attached. Subsequent examination of living giant toads collected at another Miami area site from 1983 through 1985 revealed larval, nymphal, and adult A. rotundatum and confirmed colonization of this tick. Under laboratory conditions, another neotropical amphibian and reptile tick, Amblyomma dissimile, is capable of transmitting Cowdria ruminantium, the causative agent of heartwater, a disease present in the Caribbean area. Therefore, we suggest that A. rotundatum should also be tested for vectorial competence.

The structure of Haller's organ in all major groups of soft ticks, family Argasidae, is reexamined, and hypotheses of setal homology are proposed based on a comparative study of developmental patterns. The larvae of most taxa have 7 setae in the anterior pit (1 serrate, 1 conical, 2 fine, 2 porose, 1 grooved) and 4 porose setae in the capsule. The postlarval stages add up to 3 setae to the anterior pit (1 serrate, 1 porose, 1 grooved) and up to 3 porose setae to the capsule. Preliminary hypotheses of polarity, distinguishing ancestral from derived character states, are generated for most characters examined by comparisons with results obtained for the other major family of ticks, Ixodidae, and (where possible) other members of Parasitiformes. Most of the variability in the setal complement of the anterior pit and capsule results from paedomorphosis, and nearly all the observed changes in the setal complement (both modifications of addition patterns and changes in fundamental numbers) are restricted to single species or small species groups. A correlation between changes in Haller's organ structure and changes in life history patterns is suggested but cannot be confirmed based on presently available data.

The role of the synganglion in oocyte development in Ornithodoros parkeri was investigated by ligation and transplantation experiments. Ligation between legs 2 and 3 to isolate the synganglion from the ovary and ligation between legs 1 and 2 to keep both the synganglion and the ovary in the posterior ends were performed on mated females on different days after feeding. Results show that vitellogenesis was inhibited significantly if the synganglion was separated from the ovary within the first few days after feeding. However, transplantation of synganglia from 3 kinds of donors (unfed virgin, fed virgin, and fed mated females) into the synganglionless posterior portions induced vitellogenesis and oocyte development to final maturation. The supra- and subesophageal parts of the synganglion showed a similar gonadotropic activity after each was transplanted separately into the ligated synganglionless posterior portions. These results indicate that the synganglion produces an egg development stimulation factor (EDSF) that possibly is present in a storage form in unfed and/or fed virgin females in which vitellogenesis has not progressed and is released in females after feeding and mating. However, the characterization of EDSF and precise sites of production and storage await further investigation.

The effects of metepa on the cytology and fertility of male Dermacentor variabilis treated as unfed adults are determined. Evidence of cellular damage is found in testicular areas where actively dividing cells and some enlarging spermatocytes are found. The amount of cellular damage correlates positively to the concentration of the chemosterilant and results in decreases numbers of spermatids. In crosses of treated males to untreated females, resulting egg masses hatch normally; however, the percentage of females producing egg masses that hatch is reduced.

Log-log plots of unfed and fed tick weight on corresponding values of the scutal index (SI = scutal length x scutal width) show similar slopes for female D. variabilis from two laboratory populations. As derived from these plots, the relative engorgement state of a tick at any time during feeding can be expressed as the ratio of the cube roote of weight to the square root of the scutal index (RES = W1/3 divided by SI 1/2), where SI serves as an independent measure of tick size. After feeding for specified periods, mean population fed-weights are not statistically different, but differences between mean population RES ratios are highly significant. When SI is used as a covariate, differences between mean population fed-weights are also highly significant. Tests of mean log-fed-weight and mean RES values show that the effects of individual rabbit hosts on feeding performance are highly significant, but the statistic associated with differences between RES means is higher than that between log-fed-weight means. We conclude that differences in tick engorgement behaviors are measured more sensitively by RES ratios than by engorgement weights.

Morphological characters are measured from each tick specimen from samples of 10 "populations" of Haemaphysalis longicornis. The 10 populations consist of 6 diploid bisexual and 4 triploid parthenogenetic populations from Australia, Japan, and Korea. Statistical analyses (univariate and multivariate) of differential morphological variation are made among sex, method of reproduction, and chromosome ploidy level in attempts to determine the effects of these parameters on overall variation. In general, laboratory-reared thelytokous females (3n = 33y are least variable, laboratory-reared bisexual females and males (2n = 22 female; 21 male) are intermediate in variation, and field-collected bisexual males and females are most variable. However, the only field-collected thelytokous "population" (3n = 33) in the analyses is more variable than even the field-collected bisexual ticks.

The peripheral nervous system of an ixodid and an argasid tick include the following components: (1) paired optic, cheliceral and pedipalpal nerves and unpaired stomodeal nerve arising from the pre-esophageal portion of the central nervous system (synganglion); (2) 4 pairs of pedal nerve trunks (each with appendicular and hemal branches) and 4 major pairs of opisthosomal nerves (including the paraspiracular, genital, postlateral-myosomal, and ano-myosomal nerves); and (3) the lateral "sympathetic" plexuses formed by contributions of hemal nerves arising from pedal ganglia and from the paraspiracular nerves. The salivary glands are multiply innervated by 4 pairs of nerves. The 1st pair arise from the pedipalpal nerves, the 2nd and 3rd from the lateral sympathetic plexuses, and the 4th from the paraspiracular nerves. Portions of the integument and the majority of non-appendicular muscles are innervated by various fine nerves arising from the lateral sympathetic plexuses and from the 4 pairs of opisthosomal nerves.

Fumigation of eggs with the antiallatotropin precocene 2(P2) disrupted development late in embryogenesis in the American dog tick Dermacentor variabilis. An age (time) gradient of responses in embryos was noted. Subsequent developmental effects included partial failure of stadia to attach, feed, ecdyse and partial-to-complete sterility in adult females. No precocious metamorphosis or adultiformes were observed, but a change in sex ratio of surviving adults was noted. A subsequent application of juvenile hormone 3 (JH 3) to P2-sterilized females enabled them to feed and successfully complete the gonadotrophic cycle. Restoration of gonadotrophic function by exogenous JH 3 suggested the possibility of a naturally occurring JH in D. variabilis.

Hemocoelic injection and vaginal insertion of selected male reproductive and non-reproductive tissue homogenates into fed-virgin female Ornithodoros parkeri stimulated varying degrees of ovum maturation and/or oviposition during 14 and 30 day observation periods, respectively. Mean times for oviposition and mean numbers of eggs laid per ovipositing female receiving hemocoelic injections of male reproductive tissue homogenates did not differ significantly from fed-mated controls. In addition, hemocoelic injection of male salivary glandular homogenate induced oviposition, yet synganglial homogenate did not. Although vaginal insertion induced both ovum maturation and oviposition, the effect was not as pronounced as when similar doses were administered by hemocoelic injection. These results indicate that a complex interrelated series of precopulatory and copulatory stimuli are necessary for oviposition to occur in fed O. parkeri.

The male reproductive system consists of paired tests, vasa deferentia and dark-staining lateral accessory glands, single ventromedial spongy accessory gland, seminal vesicle, ejaculatory apparatus, and gonopore. The female system consists of paired rami sacculi, sacculus foemineus, ovary (lyriform and medial portions), oviduct, vagina, and paired vaginal glands.

Protonymphal Dermanyssus gallinae were irradiated with 0.50, 0.75, 1.0, 3.0, and 6.0 krad of gamma radiation and subsequently monitored regarding their developmental, feeding, and mating success. Also, sex ratios of adults treated as protonymphs were recorded as were sex ratios of embryos and F1 adults produced by these adults. Doses up to 1.0 krad did not prevent development of treated protonymphs to the adult stage or stop mating. Three krad reduced the number of treated protonymphs attaining adulthood and 6.0-krad treatment prevented all mites from developing to the adult stage. Egg (embryo) production was normal for mites treated with 0.50 krad, but significantly curtailed by doses of 0.75 krad and greater. Radiation doses used in this study did not appear to affect the normal variable sex ratios observed in untreated mites.

The effects of different temperatures on the expression of autogenic development in unfed/mated Ornithodoros parkeri Cooley females were examined. High temperature (29 C) induced autogeny in lower, middle and higher weight classes (11-20, 21-30, 31-40 mg, respectively) with all females in the highest weight class and most in the middle weight class ovipositing within 51 days post-mate. At a lower temperature (21 C) autogenic development was not expressed by higher and middle weight females, whereas lower weight females exhibited similar degrees of autogeny at both temperatures. Results are discussed in relation to presumptive factors involved in the control and mediation of autogeny.

Amblyomma americanum males were treated with 0.5, 1, 2, 3, 4, 8, and 16 krad of gamma radiation. Testes of ticks treated with 2, 3, 4, 8, and 16 krad were smaller than those of ticks irradiated at lower levels and controls. No recognizable alteration in timing of spermatogenesis was noted among the different radiation groups, but severe breakdown and depletion of germinal cells was noted at 4, 8, and 16 krad. Percent hatch of larvae from crosses of irradiated males and untreated females decreased with increasing radiation level. No hatch was observed from eggs of females mated to males treated at 2 krad or higher.

New host and distributional records, seasonal activities in Georgia, laboratory rearing data, and taxonomic description of nymphal and larval Ixodes affinis are presented. Our data expand the list of known natural hosts of this species, record for the first time several natural hosts of larvae and nymphs, provide information on feeding periods of all stages, preecdysial intervals, preovipositional, ovipositional, and incubational periods, as well as provide information on fecundity. The immatures are fully described and SEM micrographs of them are presented.