Ecological differences between two sympatric species of armadillos (Xenarthra,Mammalia) in a temperate region of Argentina

Morpho-physiological specialization related to foraging can act as constraints on behaviour and ecological patterns of abundance and distribution. We tested this prediction in two species (weeping or screaming hairy armadillos Chaetophractus vellerosus Gray, 1865 and mulitas Dasypus hybridus Desmarest, 1804) that represent the two subfamilies of armadillos (Dasypodidae, Xenarthra): Euphractinae and Dasypodinae. The first subfamily possesses a well-developed masticatory apparatus that is considered primitive within the Xenarthra, while Dasypodinae show reductions in various aspects of cranial morphology. We sampled signs (burrows and foraging holes) and captured both species on 34 farms randomly selected in the north-eastern Pampas region of Argentina. We analyzed several niche dimensions. The two species showed significant differences in habitat use, seasonal patterns and diet. Weeping armadillos were generalists in their diet and active throughout the year. They were associated with calcareous-sand soil, as expected for a burrowing animal of the deserts. They tolerated a wide range of environmental conditions. We found that mulitas are myrmecophagous, and that they demonstrated a reduction in body temperature and activity during the cold season. As expected from their geographical distribution, mulitas used mainly vegetation with high cover and were associated with humic soils. Niche segregation between the two species of armadillos appeared to originate from different degrees of dietary specialization.     

Influence of topography on the location and density of armadillo burrows (Dasypodidae: Xenarthra) in the central Amazon, Brazil

Armadillos (Dasypodidae: Xenarthra) are the principal group of burrow-excavating mammals in Amazonian forest. Little is known about how the landscape's physical characteristics influence where these organisms choose to construct their burrows. We measured topographic characteristics of armadillo burrow placement and evaluated whether these variables affect overall burrow density. Our study took place on the study sites of the Biological Dynamics of Forest Fragments Project in the central Amazon, Brazil. To determine if armadillos exhibit habitat use preferences in constructing their burrows, we quantified the declination and elevation of available terrain along transect lines on our study sites and compared this with the characteristics of areas containing burrows. We also tested whether topographic variables were related to burrow density. Armadillos preferentially build burrows on low elevation, inclined terrain, and declination was positively related to burrow density. Low, inclined areas correspond to slopes next to stream basins. It may require less effort for armadillos to excavate these areas, while also providing proximity to water. The results of this study indicate that topographic information is important to consider when using burrows to estimate habitat use and density of armadillos in terra-firme forests of the central Amazon.     

Leprosy in armadillos (Dasypus novemcinctus) from Texas

Tissue sections from 237 nine-banded armadillos (Dasypus novemcinctus) from 51 central Texas counties were examined microscopically for acid-fast bacilli and/or lesions of leprosy. Neither were found. A review of the literature relative to the incidence of leprosy from armadillos in Texas indicates that residents of counties along the Texas Gulf Coast may be at risk of contracting leprosy by handling infected armadillos or their tissues.     

Observations of Strange-tailed Tyrants (Alectrurus risora) and other grassland birds following army ants and armadillos

ABSTRACT.   Birds in Neotropical forests frequently follow army ants to forage for insects. Here we report the first record of several species of Neotropical grassland birds following army ants ( Labidus praedator ) and yellow armadillos ( Euphractus sexcinctus ). We observed Strange-tailed Tyrants ( Alectrurus risora ) following army ants in El Bagual Ecological Reserve in Argentina. Other species also observed following army ants included Pampas Finches ( Embernagra platensis ), Wedge-tailed Grass-finches ( Emberizoides herbicola ), Long-tailed Reed-finches ( Donacospiza albifrons ), Great Kiskadees ( Pitangus sulphuratus ), Rufous Horneros ( Furnarius rufus ), Gray Monjitas ( Xolmis cinerea ), and Pale-breasted Spinetails ( Synallaxis albescens ). Strange-tailed Tyrants and Wedge-tailed Grass-finches were also observed following armadillos. Because birds were observed capturing insects flushed by the army ants and armadillos, our observations indicate that birds that opportunistically follow army ants and armadillos benefit from the association.     

The lesions and prevalence of Trypanosoma cruzi in opossums and armadillos from southern Louisiana

The prevalence of Trypanosoma cruzi in 48 opossums and 98 armadillos from southern Louisiana was studied. Sixteen opossums (33.3%) and 1 armadillo (1.1%) were positive for T. cruzi by blood culture. Hearts from 45 opossums and the tissues from the 1 blood culture-positive armadillo were available for histopathological examination. Although histopathology revealed T. cruzi pseudocysts in 6 opossums, 2 were not positive on blood culture. Therefore, 18 opossums (37.5%) were positive for T. cruzi. Twenty-two of 45 opossums had histological evidence of myocarditis. No lesion typical of infection with T. cruzi was observed in the armadillo tissues. These results substantiate that the opossum is a current reservoir host of T. cruzi infection in southern Louisiana and that armadillos may be of relatively minor importance.     

Genomic evidence for rod monochromacy in sloths and armadillos suggests early subterranean history for Xenarthra

Rod monochromacy is a rare condition in vertebrates characterized by the absence of cone photoreceptor cells. The resulting phenotype is colourblindness and low acuity vision in dim-light and blindness in bright-light conditions. Early reports of xenarthrans (armadillos, sloths and anteaters) suggest that they are rod monochromats, but this has not been tested with genomic data. We searched the genomes of Dasypus novemcinctus (nine-banded armadillo), Choloepus hoffmanni (Hoffmann''s two-toed sloth) and Mylodon darwinii (extinct ground sloth) for retinal photoreceptor genes and examined them for inactivating mutations. We performed PCR and Sanger sequencing on cone phototransduction genes of 10 additional xenarthrans to test for shared inactivating mutations and estimated the timing of inactivation for photoreceptor pseudogenes. We concluded that a stem xenarthran became an long-wavelength sensitive-cone monochromat following a missense mutation at a critical residue in SWS1, and a stem cingulate (armadillos, glyptodonts and pampatheres) and stem pilosan (sloths and anteaters) independently acquired rod monochromacy early in their evolutionary history following the inactivation of LWS and PDE6C, respectively. We hypothesize that rod monochromacy in armadillos and pilosans evolved as an adaptation to a subterranean habitat in the early history of Xenarthra. The presence of rod monochromacy has major implications for understanding xenarthran behavioural ecology and evolution.     

Cold-induced fever and peak metabolic rate in the nine-banded armadillo (Dasypus novemcinctus)

In response to cold exposure, some mammals, including the nine-banded armadillo (Dasypus novemcinctus), exhibit an increase in core temperature. This response, which can be qualified as a cold-induced fever, could increase cold tolerance by increasing peak metabolic rates because of the Q(10) effects. This hypothesis, however, is not compatible with the observation that peak core temperature can occur up to 100 min before peak metabolic rate in nine-banded armadillos during acute exposure to cold heliox (79% He; 21% O(2)). This temporal separation between the timing of peak metabolic rate and core temperature could be the result of regional heterothermy, of the confounding effects of activity, or of using heliox as a respiratory gas. We tested these potential sources of error by exposing nine-banded armadillos to cold air while simultaneously monitoring behavior, metabolic rates (V dot o2 and V dot co2), and four core temperatures. Cold air exposure resulted in a smaller but significant temporal separation, with peak core temperature occurring on average 10 min before peak metabolic rate. Animals exhibited low activity levels, and the four core temperatures changed according to the same temporal pattern, thus eliminating the possibility that activity or regional heterothermy caused the temporal separation. Using a conceptual model, we propose that the temporal separation resulted from a rate of cooling that was too fast.     

The nine-banded armadillo (Dasypus novemcinctus) is naturally infected with Sarcocystis neurona

Sarcocysts were dissected from the tongue of a nine-banded armadillo (Dasypus novemcinctus). DNA was extracted and characterised by PCR amplification followed by restriction fragment length polymorphism analysis and nucleotide sequencing. A total of 1879 nucleotides were compared; the sarcocyst DNA sequence was identical to that reported for Sarcocystis neurona. DNA was extracted from the sarcocysts of five more nine-banded armadillos. A 254-nucleotide sequence was determined for each and found to be identical to S. neurona. Western blot techniques for detection of anti-S. neurona antibody were developed for use with armadillo plasma and samples from 19 wild-caught and 17 captive-raised armadillos were examined. Whereas all of the 19 wild-caught armadillos had antibodies to S. neurona, only one of 17 captive-raised armadillos did. These results suggest that the nine-banded armadillo are naturally infected with S. neurona.     

Technique,Safety, and Efficacy of Intra-Abdominal Transmitters in Nine-Banded Armadillos

ABSTRACT The future management of nine-banded armadillos (Dasypus novemcinctus) requires solid space-use and activity data, which are currently lacking and which radiotelemetry can provide. External radiotransmitters have not been successful applied with this species. To make recommendations for intra-abdominal radiotransmitter placement in nine-banded armadillos, we 1) evaluated 4 different anesthetic protocols for safety, efficiency, and cost-effectiveness; 2) evaluated a surgical technique for the intra-abdominal placement of radiotransmitters that addresses problems described in previous studies; and 3) evaluated the physiologic and behavioral effects of such a technique. We captured and surgically implanted 37 nine-banded armadillos using either butorphanol and isoflurane, ketamine alone, ketamine and xylazine, or a combination of butorphanol, ketamine, and medetomidine for anesthesia. We recovered and necropsied armadillos after the completion of the study. The objective and subjective assessment of butorphanol, ketamine, and medetomidine combination protocol, followed by reversal of the anesthesia with atipamezole, showed that it was the best overall anesthetic protocol for field use, providing both a smooth induction and fast recovery. We evaluated the fate and effects of radiotransmitters on 13 recovered animals at the end of the study and found no adverse effects. We recommend the implantation of radiotransmitters that are allowed to free-float within the abdominal cavity and specifically emphasize the need for strict aseptic technique. Wildlife managers and wildlife veterinarians aiming to implant nine-banded armadillos with radiotransmitters will benefit from using the recommended anesthetic protocol and surgical technique in future studies.     

Plasma and erythrocyte cholinesterase values for the common long-nosed armadillo, Dasypus novemcinctus

Plasma and erythrocyte cholinesterase activities were determined for 40 free-living and 12 captive common long-nosed armadillos (Dasypus novemcinctus) in order to establish normal values for monitoring pesticide exposure. Plasma cholinesterase activity ranged from 105 to 549 U/liter with no sexual or seasonal differences. Plasma values from captive animals were significantly lower than those from wild armadillos. Erythrocyte cholinesterase activity ranged from 2,915 to 15,126 U/liter with no differences detected between captive and wild animals or between sexes. However, erythrocyte cholinesterase values varied seasonally. Erythrocyte and plasma cholinesterase activities were not significantly correlated. Packed cell volume ranged from 24 to 51% and did not vary significantly between captive and wild samples, between sexes or among seasons. However, both whole blood and erythrocyte cholinesterase activities showed significant negative correlations with packed cell volume. Controlled experiments are needed to find the factors responsible for the statistically significant difference between plasma cholinesterase activities of captive and wild armadillos. The seasonal variation in erythrocyte cholinesterase activity and the negative correlation between erythrocyte cholinesterase activity and packed cell volume can be explained by an hypothesis that relates the variation in erythrocyte cholinesterase activity to variation in erythrocyte turnover rate. Future work should involve experiments to test this hypothesis.     

Nine‐banded armadillo (Dasypus novemcinctus) activity patterns are influenced by human activity

As the human footprint upon the landscape expands, wildlife seeking to avoid human contact are losing the option of altering their spatial distribution and instead are shifting their daily activity patterns to be active at different times than humans. In this study, we used game cameras to evaluate how human development and activity were related to the daily activity patterns of the nine‐banded armadillo (Dasypus novemcinctus) along an urban to rural gradient in Arkansas, USA during the winter of 2020–2021. We found that armadillos had substantial behavioral plasticity in regard to the timing of their activity patterns; >95% of armadillo activity was nocturnal at six of the study sites, whereas between 30% and 60% of activity occurred during the day at three other sites. The likelihood of diurnal armadillo activity was best explained by the distance to downtown Fayetteville (the nearest population center) and estimated ambient sound level (both indices of human activity) with armadillos being most active during the day at quiet sites far from Fayetteville. Furthermore, armadillo activity occurred later during the night period (minutes after sunset) at sites near downtown and with higher anthropogenic sound. Anecdotal evidence suggests that the observed activity shift may be in response to not only human activity but also the presence of domestic dogs. Our results provide further evidence that human activity has subtle nonlethal impacts on even common, widespread wildlife species. Because armadillos have low body temperatures and basal metabolism, being active during cold winter nights likely has measurable fitness costs. Nature reserves near human population centers may not serve as safe harbors for wildlife as we intend, and managers could benefit from considering these nonlethal responses in how they manage recreation and visitation in these natural areas.     

The armadillo: a model for the neuropathy of leprosy and potentially other neurodegenerative diseases

Leprosy (also known as Hansen’s disease) is an infectious peripheral neurological disorder caused by Mycobacterium leprae that even today leaves millions of individuals worldwide with life-long disabilities. The specific mechanisms by which this bacterium induces nerve injury remain largely unknown, mainly owing to ethical and practical limitations in obtaining affected human nerve samples. In addition to humans, nine-banded armadillos (Dasypus novemcinctus) are the only other natural host of M. leprae, and they develop a systemically disseminated disease with extensive neurological involvement. M. leprae is an obligate intracellular parasite that cannot be cultivated in vitro. Because of the heavy burdens of bacilli they harbor, nine-banded armadillos have become the organism of choice for propagating large quantities of M. leprae, and they are now advancing as models of leprosy pathogenesis and nerve damage. Although armadillos are exotic laboratory animals, the recently completed whole genome sequence for this animal is enabling researchers to undertake more sophisticated molecular studies and to develop armadillo-specific reagents. These advances will facilitate the use of armadillos in piloting new therapies and diagnostic regimens, and will provide new insights into the oldest known infectious neurodegenerative disorder.     

Coccidioides immitis isolated from armadillos (Dasypus novemcinctus) in the state of Piauí, northeast Brazil

Natural infection of armadillos with Coccidioides immitis was studied in the state of Piauí, northeast of Brazil, endemic for coccidioidomycosis. In 1998, 26 nine-banded armadillos (Dasypus novemcinctus) were captured in 4 different counties. The animals were sacrificed under deep anesthesia with ether. At necropsy fragments of spleen, liver, lungs and heart were homogenized and seeded onto Sabouraud dextrose agar with and without cycloheximide (BBL, USA). Part of each organ was also processed for histological examination. Suspected colonies of filamentous fungi observed after the second week of incubation at room temperature, exhibiting barrel-shaped arthroconidia alternating with empty spaces, were inoculated intraperitoneally into mice. Three armadillos proved to be infected with C. immitis. Mice inoculated with suspected colonies obtained from homogenized spleen of three and liver of two armadillos developed disseminated coccidioidomycosis and immature and mature spherules of C. immitis were disclosed in several organs. For the first time armadillos (D. novemcinctus) were found naturally infected with C. immitis, adding new data on the ecology and on a possible role of these ancestral mammals in the evolutionary life cycle of this fungus. This revised version was published online in July 2006 with corrections to the Cover Date.     

Earthworms near leprosy patients' homes are negative for acid-fast bacilli by fite stain,providing no link between leprous armadillos (Dasypus novemcinctus) and human leprosy

Enzootic leprosy has been recognized in armadillos in Louisiana since 1975. Contact with armadillos is being assessed as a risk factor for leprosy in three white women, lifelong residents of separate rural areas in northern Louisiana, which is a region without endemic leprosy. None has had any known exposure to human leprosy. Each was aware of armadillos (Dasypus novemcinctus) near or under her home for decades. In considering Possible environmental sources forMycobacterium leprae, we observed that all three had earthworm growth areas for fishing bait where soil was kept moist near their homes. The worms attracted armadillos. Since armadillos subsist on worms, grubs, and insects and because of the common feature of a worm farm near each home, we reasoned that earthworms might containM. leprae and be part of a cycle involving the armadillo and human beings. Worms from each home worm farm were studied. One site was sampled twice at patient 1's home, five sites were sampled once at patient 2's home, and three sites were sampled once at patient 3's home. A sample consisted of 3–4 worms, which were washed, purged, fixed live in 10% formalin, embedded in paraffin, sectioned, and stained with the Fite stain. Each was sagittally sectioned and examined by three independent observers. No acid-fast bacilli or other acid-fast structures were identified. We conclude that it is unlikely that earthworms are an environmental source or reservoir ofM. leprae.     

Diet of the maned wolf, Chrysocyon brachyurus, in central Brazil

Analysis of 105 scats of the maned wolf ( Chrysocyon brachyurus ) collected in central Brazil yielded 304 occurrences of food items of which fruits of Solanum lycocarpum , rodents, and birds accounted for 61.5%. By analysis of minimum number of individual animals, rodents and birds were 75% of a total of 156 prey. On the other hand, fruits of S. lycocarpum and armadillos ( Dasypus spp.) were the bulk of the total estimated biomass consumption, yielding 63.7% in a total of 73.5 kg. Rodents were mostly captured during the dry season, while miscellaneous fruits were consumed mostly in the wet season. The consumption of S. lycocarpum fruits and armadillos was aseasonal. Small rodents were taken in about the ranks of abundance in the study area, but S. lycocarpum fruits were actively searched by maned wolves, for its occurrence is limited to secondary savanna. Prey and fruits typical of savanna ('cerrado') and grassland ('campo') were the bulk of species, occurrences, prey numbers, and biomass consumed. These findings reinforce the importance of conservation of cerrado and campo in central Brazil. Despite maned wolf being a vulnerable species, its feeding habits are opportunistic, and the main reasons for its decline are likely to be habitat destruction and human disturbance.     

Armadillos exhibit less genetic polymorphism in North America than in South America: nuclear and mitochondrial data confirm a founder effect in Dasypus novemcinctus (Xenarthra)

Heterozygosity at eight nuclear enzymatic loci and mitochondrial DNA control region (D-loop) sequence polymorphism was compared between North and South American nine-banded armadillos (Dasypus novemcinctus: Xenarthra, Dasypodidae). All markers revealed a striking genetic homogeneity amongst Texas, Louisiana, and Mississippi individuals, vs. the usual level of polymorphism for the French Guiana population. This may reflect a founder effect during colonization of North America. Occurrence of polymorphism in the D-loop microsatellite motif of North American armadillos suggests a recent recovery of mitochondrial variability. Phylogeographic analyses using Dasypus kappleri as outgroup provides evidence for a clear separation between North and South American control region haplotypes.     

Ancient DNA from the extinct South American giant glyptodont Doedicurus sp. (Xenarthra: Glyptodontidae) reveals that glyptodonts evolved from Eocene armadillos

Glyptodonts were giant (some of them up to ~2400 kg), heavily armoured relatives of living armadillos, which became extinct during the Late Pleistocene/early Holocene alongside much of the South American megafauna. Although glyptodonts were an important component of Cenozoic South American faunas, their early evolution and phylogenetic affinities within the order Cingulata (armoured New World placental mammals) remain controversial. In this study, we used hybridization enrichment and high‐throughput sequencing to obtain a partial mitochondrial genome from Doedicurus sp., the largest (1.5 m tall, and 4 m long) and one of the last surviving glyptodonts. Our molecular phylogenetic analyses revealed that glyptodonts fall within the diversity of living armadillos. Reanalysis of morphological data using a molecular ‘backbone constraint’ revealed several morphological characters that supported a close relationship between glyptodonts and the tiny extant fairy armadillos (Chlamyphorinae). This is surprising as these taxa are among the most derived cingulates: glyptodonts were generally large‐bodied and heavily armoured, while the fairy armadillos are tiny (~9–17 cm) and adapted for burrowing. Calibration of our phylogeny with the first appearance of glyptodonts in the Eocene resulted in a more precise timeline for xenarthran evolution. The osteological novelties of glyptodonts and their specialization for grazing appear to have evolved rapidly during the Late Eocene to Early Miocene, coincident with global temperature decreases and a shift from wet closed forest towards drier open woodland and grassland across much of South America. This environmental change may have driven the evolution of glyptodonts, culminating in the bizarre giant forms of the Pleistocene.     

Armadillo leprosy and a failed vaccine

In 1974, scientists at Gulf South Research Institute (GSRI) in New Iberia, Louisiana, showed that armadillos experimentally infected with leprosy could produce 10¹⁴ bacilli per animal within two years. These vast numbers inspired World Health Organization (WHO) to initiate an international program for development of an anti-leprosy vaccine. US Public Health Service (USPHS) staff at Carville, LA, wrongfully accused GSRI of causing a leprosy zoonosis in wild armadillos. As a result, the GSRI program was terminated in 1979. The talisman for obtaining high yields of bacilli was lost, causing productivity to decrease by two to three orders of magnitude. Nevertheless, field trials on the vaccine continued through 1998. Results published in 1992 on 29,000 volunteers in Venezuela showed that the vaccine when used in combination with BCG was no more effective than BCG alone. Laboratory tests published three years later revealed that the vaccine used in Venezuela had little if any immunoreactivity. A report published in 1996 showed that the vaccine was ineffective in field trials on 112,000 volunteers in Malawi. It is possible that the poor quality of these vaccines can be traced to the catastrophic decline in numbers of bacilli produced by armadillos.     

Dental microwear in the orthodentine of the Xenarthra (Mammalia) and its use in reconstructing the palaeodiet of extinct taxa: the case study of Nothrotheriops shastensis (Xenarthra,Tardigrada, Nothrotheriidae)

The utility of orthodentine microwear analysis as a proxy for dietary reconstruction in xenarthrans (tree sloths, armadillos) was quantitatively and statistically accessed via low‐magnification stereomicroscopy. Features such as number of scratches and pits, as well as presence of gouges, hypercoarse scratches, > four large pits, > four cross scratches, and fine, mixed or coarse scratch texture were recorded in 255 teeth from 20 extant xenarthran species. Feature patterns are consistent with scar formation through abrasional (tooth–food) and attritional (tooth–tooth) contact. Number of scratches is the most dietary diagnostic microwear variable for xenarthrans, with herbivorous sloths characterized by > ten scratches and nonherbivorous armadillos by < ten scratches. Discriminant function analysis differentiated arboreal folivores (sloths) and frugivore‐folivores (sloths) both from each other and from fossorial carnivore‐omnivores (armadillos) and insectivores (armadillos). Microwear patterns in carnivore‐omnivores and insectivores are difficult to distinguish between; armadillo microwear may reflect a fossorial lifestyle (grit consumption) rather than primary diet. Cabassous centralis is anomalous in its microwear signal relative to all other insectivores. To test the utility of orthodentine microwear analysis as an indicator of palaeodiet in extinct xenarthrans, microwear in the ground sloth Nothrotheriops shastensis was quantitatively and statistically compared to microwear in extant taxa. Microwear patterns in N. shastensis are most comparable to extant folivores based on scratch number and hierarchical cluster analysis. This strongly supports an herbivorous diet for N. shastensis that is corroborated by multiple independent lines of evidence. Thus, orthodentine microwear analysis can be used to reconstruct diet in extinct xenarthrans. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 201–222.     

Helminth fauna of the nine-banded armadillo (Dasypus novemcinctus) in north-central Florida

The gastrointestinal tracts of 32 free-ranging, 9-banded armadillos (Dasypus novemcinctus) from north-central Florida were examined for the presence of helminths during July 1991 to November 1993. Aspidodera sp. (Nematoda: Aspidoderidae), most closely resembling Aspidodera sogandaresi, were recovered from 20 of 32 armadillos examined. Total numbers of A. sogandaresi ranged from 1 to 1,021 per infected animal, and followed an inverse correlation to body condition index for those animals. The cystacanth stage of 1 acanthocephalan, Macracanthorhynchus ingens, was present in 1 armadillo, and is the first report of M. ingens in the 9-banded armadillo. The present study contributes to the known natural history of the 9-banded armadillo, an important animal research model.