Tadarida Brasiliensis Research Articles

Cross-genus amplification and characterisation of microsatellite loci in the little free tailed bat, Chaerephon pumilus s. l. (Molossidae) from South Eastern Africa

Microsatellite loci for Chaerephon pumilus sensu lato from south eastern Africa were cross-amplified using primers developed for the Mexican free-tailed bat, Tadarida brasiliensis . Two dinucleotide and four tetranucleotide loci were recovered and genotyped for 74 bats, yielding 9 to 15 alleles per locus. The observed and expected heterozygosities were 0.06 to 0.84 and 0.54 to 0.81 respectively, and the PIC values ranged from 0.51 to 0.80, indicative of considerable variability within the sample. There was no evidence of linkage disequilibrium among pairs of loci, or of deviation from Hardy-Weinberg equilibrium. These six loci were informative in studies of population genetic structure of C. pumilus sensu lato. Keywords : Bats, Chaerephon pumilus, Chiroptera, microsatellites, Molossidae, cross-genus amplification African Journal of Biotechnology Vol. 12(21), pp. 3143-3147

Social context evokes rapid changes in bat song syntax

The capacity to modify vocal syntax to changes in social context is an important component of vocal plasticity and complexity in adult vertebrates, especially in human speech. The ecological significance of this behaviour has been well established in some avian species but not in mammals where complex, multisyllabic vocalizations are rare. The Brazilian free-tailed bat, Tadarida brasiliensis, is a mammal that sings like a bird, producing hierarchically structured songs that vary in the order and number of phrases (i.e. syntax) from one rendition to the next while simultaneously following specific organizational rules. Here, we used playback experiments to examine the function of songs and tested whether song syntax is correlated with social context. Free-tailed bats responded rapidly and robustly to echolocation calls that mimicked a bat flying past the roost but did not respond to conspecific song playbacks. We compared songs that were directed at a passing bat with songs that were produced spontaneously and found that bats produced longer songs with different phrase content and order when singing spontaneously than when singing to bats approaching their roost. Thus, free-tailed bats quickly varied song composition to meet the specific demands of different social functions. These distinct singing behaviours are similar to those of some songbirds, suggesting that bats and birds have converged upon a similar set of production modes that may reflect common neural mechanisms and ecological factors.

Bats of Palo Duro Canyon State Park, Texas: Community Composition, Abundance, and Seasonal Activity

ABSTRACT. Basic natural history information is lacking for many bats, especially for bats of the Texas Panhandle. We examined community composition, relative abundance, and seasonal activity of bats in Palo Duro Canyon State Park, Texas, using 3 survey methods (mist net, roost surveys, and acoustic monitoring) between July 2006 and May 2009. Twelve species of bats were captured or observed, with the Brazilian free-tailed bat (Tadarida brasiliensis), canyon bat (Parastrellus hesperus), and big brown bat (Eptesicus fuscus) being the most common. Acoustic calls of 2 additional species, most likely the California myotis (Myotis californicus) and big free-tailed bat (Nyctinomops macrotis), were also recorded. The Brazilian free-tailed bat was captured year-round, and an evening bat (Nycticeius humeralis), uncommon in the area, was captured. This study increases our understanding of the occurrence, abundance, and seasonality of bats in the Texas Panhandle.

Molecular detection of Neorickettsia risticii in Brazilian free-tailed bats (Tadarida brasiliensis) from Buenos Aires , Argentina

Neorickettsia risticii is the causative agent of Potomac Horse Fever, a severe febrile disease affecting horses, transmitted by trematodes species with a complex life cycle. A total of 30 insectivorous bats (Brazilian free-tailed bat Tadarida brasiliensis) were analyzed by PCR for presence of genus Anaplasma, Ehrlichia, Neorickettsia and Rickettsia. Three samples showed positive reactions for genus Anaplasma, Ehrlichia and Neorickettsia, and the sequences were 99.67% identical to Neorickettsia risticii. The role of bats in the life cycle of N. risticii has yet to be elucidated; however bats may be reservoirs for this bacterium. To our knowledge, this is the first evidence of N. risticii in Argentina.

Circuits That Innervate Excitatory-Inhibitory Cells in the Inferior Colliculus Obtained with In Vivo Whole Cell Recordings

Neurons excited by stimulation of one ear and suppressed by the other, called excitatory/inhibitory (EI) neurons, are sensitive to interaural intensity disparities, the cues animals use to localize high frequencies. EI neurons are first formed in lateral superior olive, which then sends excitatory projections to the dorsal nucleus of the lateral lemniscus and the inferior colliculus (IC), both of which contain large populations of EI cells. We evaluate herein the inputs that innervate EI cells in the IC of Mexican free-tailed bats (Tadarida brasilensis mexicana) with in vivo whole-cell recordings from which we derived excitatory and inhibitory conductances. We show that the basic EI property in the majority of IC cells is inherited from lateral superior olive, but that each type of EI cell is also innervated by the ipsilateral or contralateral dorsal nucleus of the lateral lemniscus, as well as additional excitatory and inhibitory inputs from monaural nuclei. We identify three EI types, each of which receives a set of projections that is different from the other types. To evaluate the role that the various projections played in generating binaural responses, we used modeling to compute a predicted response from the conductances. We then omitted one of the conductances from the computation to evaluate the degree to which that input contributed to the binaural response. We show that the formation of the EI property in the various types is complex, and that some projections exert such subtle influences that they could not have been detected with extracellular recordings or even from intracellular recordings of postsynaptic potentials.

Detection of Alphacoronavirus in velvety free-tailed bats (Molossus molossus) and Brazilian free-tailed bats (Tadarida brasiliensis) from urban area of Southern Brazil

A survey was carried out in search for bat coronaviruses in an urban maternity roost of about 500 specimens of two species of insectivorous bats, Molossus molossus and Tadarida brasiliensis, in Southern Brazil. Twenty-nine out of 150 pooled fecal samples tested positive by reverse transcription-PCR contained fragments of the RNA-dependent RNA polymerase gene of coronavirus-related viruses. The sequences clustered along with bat alphacoronaviruses, forming a subcluster within this group. Our findings point to the need for risk assessment and continued surveillance of coronavirus infections of bats in Brazil.Electronic supplementary materialThe online version of this article (doi:10.1007/s11262-013-0899-x) contains supplementary material, which is available to authorized users.

Imported human rabies in Switzerland, 2012: A diagnostic conundrum

Human rabies is rare in Western Europe. It is not easily recognized in the absence of a history of exposure. We describe the clinical course, diagnosis and follow-up of an imported human rabies case in Switzerland. The patient, a U.S. citizen, presented at an outpatient clinic in Iraq with pain in his right shoulder on July 5, 2012. On July 8 he was transferred to a hospital in the United Arab Emirates, where he exhibited progressive encephalitis with coma. On July 29, he was transferred to a hospital in Switzerland, where he died on July 31, 2012. The autopsy showed severe encephalitis. Rabies was diagnosed by the rapid fluorescent focus inhibition test (RFFIT) and confirmed by fluorescence antibody testing (FAT) in brain smears and immunohistochemistry on paraffin-embedded brain sections. The viral strain was characterized by RT-PCR followed by sequencing and phylogenetic analysis as an American bat rabies strain associated with Tadarida brasiliensis. Close contacts and exposed health care workers received postexposure prophylaxis (PEP).

A Study of Mexican Free-Tailed Bat Chirp Syllables: Bayesian Functional Mixed Models for Nonstationary Acoustic Time Series

We describe a new approach to analyze chirp syllables of free-tailed bats from two regions of Texas in which they are predominant: Austin and College Station. Our goal is to characterize any systematic regional differences in the mating chirps and assess whether individual bats have signature chirps. The data are analyzed by modeling spectrograms of the chirps as responses in a Bayesian functional mixed model. Given the variable chirp lengths, we compute the spectrograms on a relative time scale interpretable as the relative chirp position, using a variable window overlap based on chirp length. We use two-dimensional wavelet transforms to capture correlation within the spectrogram in our modeling and obtain adaptive regularization of the estimates and inference for the regions-specific spectrograms. Our model includes random effect spectrograms at the bat level to account for correlation among chirps from the same bat and to assess relative variability in chirp spectrograms within and between bats. The modeling of spectrograms using functional mixed models is a general approach for the analysis of replicated nonstationary time series, such as our acoustical signals, to relate aspects of the signals to various predictors, while accounting for between-signal structure. This can be done on raw spectrograms when all signals are of the same length and can be done using spectrograms defined on a relative time scale for signals of variable length in settings where the idea of defining correspondence across signals based on relative position is sensible. Supplementary materials for this article are available online.

Pneumocystis sp. in bats evaluated by qPCR

Molecular techniques have revealed a high prevalence of Pneumocystis colonization in wild mammals. Accurate quantification of Pneumocystis sp. is essential for the correct interpretation of many research experiments investigating this organism. The objectives of this study were to detect the presence of Pneumocystis sp. in bats by qPCR, and to distinguish colonization from infection. Probes and primers for real time PCR (qPCR) were designed based on the gene of major surface glycoprotein (MSG) of Pneumocystis sp., in order to analyze 195 lung tissue samples from bats captured (2007-2009). All samples were also analyzed by nested PCR, using oligonucleotide primers designed for the gene encoding the mitochondrial small subunit rRNA (mtSSU rRNA) to confirm the results. The qPCR assay was standardized using a standard curve made with the DNA extracted from bronchoalveolar lavage positive for Pneumocystis jirovecii. The average Ct was found to be between 13 and 14 (calibration curve) for the detection of infection with Pneumocystis sp. and above these values for colonization. It was considered as negative samples the ones that had Ct values equal to 50. Out of the total 195 samples, 47 (24.1%) bat lung DNA samples were positive for Pneumocystis sp. by qPCR. The most common bat species found were: Tadarida brasiliensis (23.4%), Histiotus velatus (17.0%), Desmodus rotundus (14.9%) and Molossus molossus (8.5%). The average cycle threshold of the positive samples (bats) was 25.8 and standard deviation was 1.7. The DNA samples with Ct values greater than 14 suggest that these animals might be colonized by Pneumocystis sp. Results obtained in this study demonstrated the usefulness of the qPCR procedure for identificationof Pneumocystis sp. and for distinction between its colonizing or infectious status in bats.

Brevity is prevalent in bat short-range communication

Animal communication follows many coding schemes. Less is known about the coding strategy for signal length and rates of use in animal vocal communication. A generalized brevity (negative relation between signal length and frequency of use) is innovatively explored but remains controversial in animal vocal communication. We tested brevity for short-range social and distress sounds from four echolocating bats: adult black-bearded tomb bat Taphozous melanopogon, Mexican free-tailed bat Tadarida brasiliensis, adult greater horseshoe bat Rhinolophus ferrumequinum, and adult least horseshoe bat Rhinolophus pusillus. There was a negative association between duration and number of social but not distress calls emitted. The most frequently emitted social calls were brief, while most distress calls were long. Brevity or lengthiness was consistently selected in vocal communications for each species. Echolocating bats seem to have convergent coding strategy for communication calls. The results provide the evidence of efficient coding in bat social vocalizations, and lay the basis of future researches on the convergence for neural control on bats' communication calls.

Antigenic and genetic characterization of rabies virus isolates from Uruguay

After 25 years without any reported cases of rabies in Uruguay, the northern region of the country experienced an epizootic of bovine paralytic rabies in October 2007. The outbreak affected bovines and equines, and the main source of infection was the bat Desmodus rotundus, the only hematophagous species in the country. From October 2007 to July 2008, 42 bovine, 3 equine and 120 chiropteran samples were submitted to the National Veterinary Diagnostic Laboratory for rabies testing. A total of 12 samples (7 bovine, 2 equine and 3 from D. rotundus) were positive by the fluorescent antibody test, and viruses were isolated by the mouse inoculation test. The objective of this study was to compare the antigenic and genetic characteristics of these isolates and three isolates from insectivorous bats from other regions. Antigenic typing using a panel of eight monoclonal antibodies identified all 12 viruses as variant 3 (AgV3), a variant associated with D. rotundus. Two isolates from insectivorous bats (Tadarida brasiliensis and Molossus sp.) were characterized as antigenic variant 4 (AgV4) while the third, from Myotis sp., could not be characterized using this panel as its reactivity pattern did not match that of any of the known antigenic variants. Partial N-gene sequences (nt 149–1420) of these isolates were aligned with homologous sequences derived from GenBank by the CLUSTAL/W method and used to build a neighbor-joining distance tree with the Kimura 2-parameter model. All 12 isolates were genetically grouped into the D. rotundus cluster as they shared 100% identity. In the phylogenetic analysis, the three isolates from insectivorous bats segregated into three clusters: one related to T. brasiliensis, one to Myotis sp. and the other to Lasiurus sp., although the isolate associated with the latter came from a Molossus sp. specimen. These results indicate that AgV3 was associated with the outbreak of bovine paralytic rabies in Uruguay. This is the first report of rabies virus having been detected in non-hematophagous bats in this country.

Tourism Values for Mexican Free-Tailed Bat Viewing

Migratory species provide diverse ecosystem services to people, but these values have seldom been estimated rangewide for a single species. In this article, we summarize visitation and consumer surplus for recreational visitors to viewing sites for the Mexican free-tailed bat (Tadarida brasiliensis mexicana) throughout the Southwestern United States. Public bat viewing opportunities are available at 17 of 25 major roosts across six states; on an annual basis, we estimate that over 242,000 visitors view bats, gaining over $6.5 million in consumer surplus. A better understanding of spatial mismatches between the areas where bats provide value to people and areas most critical for maintaining migratory populations can better inform conservation planning, including economic incentive systems for conservation.

Intestinal perfusion indicates high reliance on paracellular nutrient absorption in an insectivorous bat Tadarida brasiliensis

Flying vertebrates have been hypothesized to have a high capacity for paracellular absorption of nutrients. This could be due to high permeability of the intestines to nutrient-sized molecules (i.e., in the size range of amino acids and glucose, MW 75–180Da). We performed intestinal luminal perfusions of an insectivorous bat, Tadarida brasiliensis. Using radio-labeled molecules, we measured the uptake of two nutrients absorbed by paracellular and transporter-mediated mechanisms (l-proline, MW 115Da, and d-glucose, MW 180Da) and two carbohydrates that have no mediated transport (l-arabinose, MW 150Da, and lactulose, MW 342Da). Absorption of lactulose (0.61±0.06nmolmin−1cm−1) was significantly lower than that of the smaller arabinose (1.09±0.04nmolmin−1cm−1). Glucose absorption was significantly lower than that of proline at both nutrient concentrations (10mM and 75mM). Using the absorption of arabinose to estimate the portion of proline absorption that is paracellular, we calculated that 25.1±3.0% to 66.2±7.8% of proline absorption is not transporter-mediated (varying proline from 1mM to 75mM). These results confirm our predictions that 1) paracellular absorption is molecule size selective, 2) absorption of proline would be greater than glucose absorption in an insectivore, and 3) paracellular absorption represents a large fraction of total nutrient absorption in bats.

New distributional records for bats of the Argentine Patagonia and the southernmost known record for a molossid bat in the world

We add new localities to the distribution of bats of the families Molossidae and Vespertilionidae in southern Argentina. We report the southernmost known record for any bat species of the family Molossidae in the world, which corresponds to a locality in the Argentine province of Santa Cruz, for Tadarida brasiliensis . Also, new records of this species are added to the provinces of Chubut and Río Negro. Additionally, we provide new localities that extend the distribution of some species of Vespertilionidae, by adding Histiotus magellanicus and Lasiurus varius to Chubut, and new records for Histiotus montanus to Santa Cruz and for Myotis chiloensis to Chubut and Tierra del Fuego.

Bats Track and Exploit Changes in Insect Pest Populations

The role of bats or any generalist predator in suppressing prey populations depends on the predator's ability to track and exploit available prey. Using a qPCR fecal DNA assay, we document significant association between numbers of Brazilian free-tailed bats (Tadarida brasiliensis) consuming corn earworm (CEW) moths (Helicoverpa zea) and seasonal fluctuations in CEW populations. This result is consistent with earlier research linking the bats' diet to patterns of migration, abundance, and crop infestation by important insect pests. Here we confirm opportunistic feeding on one of the world's most destructive insects and support model estimates of the bats' ecosystem services. Regression analysis of CEW consumption versus the moth's abundance at four insect trapping sites further indicates that bats track local abundance of CEW within the regional landscape. Estimates of CEW gene copies in the feces of bats are not associated with seasonal or local patterns of CEW abundance, and results of captive feeding experiments indicate that our qPCR assay does not provide a direct measure of numbers or biomass of prey consumed. Our results support growing evidence for the role of generalist predators, and bats specifically, as agents for biological control and speak to the value of conserving indigenous generalist predators.

The capacity for paracellular absorption in the insectivorous bat Tadarida brasiliensis

Water-soluble nutrients are absorbed by the small intestine via transcellular and paracellular processes. The capacity for paracellular absorption seems greater in fliers than in nonfliers, although that conclusion rests mainly on a comparison of flying birds and nonflying mammals because only two frugivorous bat species have been studied. Furthermore, the bats studied so far were relatively large (>85 g, compared with most bat species which are <20 g) and were not insectivores (like about 70 % of bat species). We studied the small (11 g) insectivorous bat Tadarida brasiliensis and tested the prediction that the capacity for paracellular absorption would be as high as in the other bat and avian species studied so far, well above that in terrestrial, nonflying mammals. Using standard pharmacokinetic technique, we measured the extent of absorption (fractional absorption = f) of inert carbohydrate probes: L-arabinose (MM = 150.13) absorbed exclusively by paracellular route and 3OMD-glucose (MM = 194) absorbed both paracellularly and transcellularly. As predicted, the capacity of paracellular absorption in this insectivorous bat was high (L-arabinose f = 1.03 ± 0.14) as in other frugivorous bats and small birds. Absorption of 3OMD-glucose was also complete (f = 1.09 ± 0.17), but >80 % was accounted for by paracellular absorption. We conclude that passive paracellular absorption of molecules of the size of amino acids and glucose is extensive in this bat and, generally in bats, significantly higher than that in nonflying mammals, although the exact extent can be somewhat lower or higher depending on molecule size, polarity and charge.

Climate and Weather Impact Timing of Emergence of Bats

Interest in forecasting impacts of climate change have heightened attention in recent decades to how animals respond to variation in climate and weather patterns. One difficulty in determining animal response to climate variation is lack of long-term datasets that record animal behaviors over decadal scales. We used radar observations from the national NEXRAD network of Doppler weather radars to measure how group behavior in a colonially-roosting bat species responded to annual variation in climate and daily variation in weather over the past 11 years. Brazilian free-tailed bats (Tadarida brasiliensis) form dense aggregations in cave roosts in Texas. These bats emerge from caves daily to forage at high altitudes, which makes them detectable with Doppler weather radars. Timing of emergence in bats is often viewed as an adaptive trade-off between emerging early and risking predation or increased competition and emerging late which restricts foraging opportunities. We used timing of emergence from five maternity colonies of Brazilian free-tailed bats in south-central Texas during the peak lactation period (15 June–15 July) to determine whether emergence behavior was associated with summer drought conditions and daily temperatures. Bats emerged significantly earlier during years with extreme drought conditions than during moist years. Bats emerged later on days with high surface temperatures in both dry and moist years, but there was no relationship between surface temperatures and timing of emergence in summers with normal moisture levels. We conclude that emergence behavior is a flexible animal response to climate and weather conditions and may be a useful indicator for monitoring animal response to long-term shifts in climate.

High Diversity of Rabies Viruses Associated with Insectivorous Bats in Argentina: Presence of Several Independent Enzootics

BackgroundRabies is a fatal infection of the central nervous system primarily transmitted by rabid animal bites. Rabies virus (RABV) circulates through two different epidemiological cycles: terrestrial and aerial, where dogs, foxes or skunks and bats, respectively, act as the most relevant reservoirs and/or vectors. It is widely accepted that insectivorous bats are not important vectors of RABV in Argentina despite the great diversity of bat species and the extensive Argentinean territory.MethodsWe studied the positivity rate of RABV detection in different areas of the country, and the antigenic and genetic diversity of 99 rabies virus (RABV) strains obtained from 14 species of insectivorous bats collected in Argentina between 1991 and 2008.ResultsBased on the analysis of bats received for RABV analysis by the National Rabies system of surveillance, the positivity rate of RABV in insectivorous bats ranged from 3.1 to 5.4%, depending on the geographic location. The findings were distributed among an extensive area of the Argentinean territory. The 99 strains of insectivorous bat-related sequences were divided into six distinct lineages associated with Tadarida brasiliensis, Myotis spp, Eptesicus spp, Histiotus montanus, Lasiurus blosseviilli and Lasiurus cinereus. Comparison with RABV sequences obtained from insectivorous bats of the Americas revealed co-circulation of similar genetic variants in several countries. Finally, inter-species transmission, mostly related with Lasiurus species, was demonstrated in 11.8% of the samples.ConclusionsThis study demonstrates the presence of several independent enzootics of rabies in insectivorous bats of Argentina. This information is relevant to identify potential areas at risk for human and animal infection.

Cat infected by a variant of bat rabies virus in a 29-year disease-free urban area of southern Brazil

After 29 years, rabies was detected in a cat in Curitiba, southern Brazil. The fluorescent antibody test (FAT) and mouse inoculation test (MIT) were performed on central nervous system (CNS) samples. Direct immunofluorescence was negative, but the biological test was positive and rabies virus was characterized as variant 4 (from Tadarida brasiliensis). Reappearance of rabies in domestic animals warns of sylvatic-aerial risk of infection and the necessity of monitoring bats in historically rabies-free areas.

Vascular Contrast Enhanced Micro‐CT Imaging of “Radiators” in the Brazilian Free‐Tailed Bat (Tadarida Brasiliensis)

The Brazilian free-tailed bat (Tadarida brasiliensis) exhibits a highly vascularized, hairless thermal window (or "radiator") on the proximal ventral surfaces of extended wings and body. We identified this character using thermal infrared imaging and investigated the vasculature using barium sulfate enhanced microcomputed tomography (micro-CT). Micro-CT images revealed unique arrangements of arteries and veins in the region of the radiator positioned perpendicular to the axis of the body. Coupling micro-CT imaging with analysis of surface temperature profiles, we concluded that radiators aid in thermoregulation during flight in variable environments. This study represents the first application of contrast enhanced micro-CT to visualize vasculature of bats and thus exhibits a promising technique for further investigations of cardiovascular function and anatomy in bats.