Effects of host state and body condition on parasite infestation of bent-wing bats

Host associations and genetic diversity of bat flies (Diptera: Nycteribiidae and Streblidae) in bats from Thailand

BACKGROUND

Bat flies belong to the order Diptera and superfamily Hippoboscoidea. They can be divided into two families, Streblidae and Nycteribiidae, which collectively encompass 239 and 280 species worldwide, respectively. In Thailand, 43 species of Nycteribiidae and 16 species of Streblidae have been documented. Despite their diversity, the molecular characteristics and host-parasite interactions of these ectoparasites remain poorly understood.

METHODS

During a bat survey conducted between 2019 and 2022, bat flies were collected across eight sites in three provinces of Thailand. Morphological identification was performed using identification keys and a bat fly checklist endemic to Thailand. DNA barcoding targeted to the mitochondrial Cox1 and nuclear 28S rRNA genes was utilized. Infestation patterns were analyzed in relation to host sex, sampling site, and physiological status. Species identification was confirmed via BLASTN searches, and species delimitation was conducted using the ASAP algorithm under three substitution models. Phylogenetic relationships were inferred using Maximum Likelihood methods, while genetic variation was assessed through TCS haplotype network analysis. Tripartite network analysis was employed to examine site-host-parasite associations.

RESULTS

A total of 1,042 bats, representing 28 species, were captured during the study, of which 298 individuals (28.59%) were infested with bat flies. In total, 773 bat flies were collected, comprising 737 from the family Streblidae and 36 from Nycteribiidae. Morphological and molecular analyses identified three genera-Raymondia, Brachytarsina, and Nycteribia-along with seven hypothetical species. Phylogenetic reconstruction using mitochondrial (Cox1) and nuclear (28S rRNA) gene markers revealed distinct clades within each genus, underscoring substantial genetic diversity. Haplotype analyses identified 18 haplotypes in Raymondia, six in Brachytarsina, and two in Nycteribia, with evidence of site-specific host-parasite associations. Infestation rates varied by host species, sex, and location, with larger bat populations demonstrating higher infestation intensities. Raymondia sp. 1 is the most frequently encountred species an predominantly infested Hipposideros gentilis.

CONCLUSIONS

This study provides the first molecular characterization of bat fly diversity in Thailand, revealing their genetic complexity, taxonomy, host specificity, and ecological interactions. The findings establish a crucial foundation for further research concerning the biodiversity, host-parasite dynamics, and zoonotic risks associated with bat flies.

Contrasting effects of body condition on ectoparasite abundance in a social bat: different roles of season and host sex

Understanding the interplay between host species ecology and parasite dynamics is crucial for comprehending disease transmission patterns, population structures, and ecosystem health. In most host-parasite systems, host body condition is of primary importance in ectoparasite host choice. Bats were considered an exception, as previously several studies suggested that bat ectoparasites showed no or minimal dependence on host body condition. We investigated the relationships between host condition and ectoparasite abundance in multiple populations of European bent-winged bats (Miniopterus schreibersii) and their arthropod ectoparasites (mites, nycteribiid bat flies and ixodid ticks). We found weak correlations between individual host condition and combined ectoparasite abundance, with seasonal fluctuations in both, and a single seasonal peak in parasite abundance. However, when treated individually, single ectoparasite groups showed contrasting answers to changes in body condition. Body condition had a significant positive effect on wing mite abundance and a significant negative effect on the prevalence and intensity of nycteribiid bat flies, overall with no effect on tick infestation. These responses moreover showed also seasonal differences, highly correlating with the life-stages of the two host's sexes. Our long-term, large-scale study of European bent-winged bats and their arthropod ectoparasites was able to detect major influences exerted by hosts' body condition on ectoparasites' host choice. Here we showed that bat populations undergo dynamic changes in their body condition during the active period of their annual cycle, with ectoparasites evolved to differentially exploit peaks or troughs of these changes.

Bat microfilariae in the cityscape: a transmission tale between bats, mites, and bat flies

Litomosoides includes filarial nematodes capable of infecting various vertebrate species. While Litomosoides has been extensively studied in rodents, research on its association with bats remains limited. The transmission dynamics of this parasite are complex, involving moving between different invertebrate hosts before reaching the final host. Most investigations concerning microfilariae have concentrated on their morphological characteristics, with scant attention paid to ecological aspects, particularly in human-altered landscapes. This study represents the first known documentation of Litomosoides in bats within an urban environment. It investigates their response to urbanization in their interaction with the synanthropic bat Artibeus jamaicensis and its ectoparasites. The objective was to explore the influence of urban landscapes on Litomosoides prevalence in synanthropic hosts. Blood samples were collected along urban-rural gradients, and parasite presence was confirmed through direct observation in blood smears and PCR. Phylogenetic analysis based on the mitochondrial cytochrome c oxidase subunit 1 gene (COX1), which exhibited robust support values, indicates that the microfilaria found in A. jamaicensis is closely related to Litomosoides chandleri. However, it also suggests the possibility of an unidentified, and therefore potentially new, species within the genus Litomosoides. Additionally, Litomosoides DNA was detected in Periglischrus iheringi (Acari: Spinturnicidae) and in the bat fly Trichobius intermedius collected from the bat. The parasite sequences obtained from these three interacting species exhibited a genetic distance as low as 0.002. The highest prevalences were recorded in forested areas (28.6%) compared with urban areas (21.2%). However, within the urban landscape, prevalence varied from 3.8% to 21.2%, being highest in densely built-up areas. Analysis of the urban landscape suggested that the prevalence of Litomosoides in A. jamaicensis is the result of a multifactorial and synergistic process involving ectoparasite load, host abundance, and the extent of impervious surfaces (NDBI).

Diversity and seasonality of ectoparasite burden on two species of Madagascar fruit bat, Eidolon dupreanum and Rousettus madagascariensis

Background

Bats are important reservoir hosts for a variety of microparasites, some of which are transmitted by ectoparasite vectors that include mites, fleas, lice, ticks, and bat flies (families Nycteribiidae and Streblidae). All of these ectoparasite taxa are known to parasitize two endemic fruit bats of Madagascar, Eidolon dupreanum and Rousettus madagascariensis. We aimed to describe the diversity of ectoparasite infestation for both bat species through morphological observation and DNA barcoding and elucidate ecological and climatic correlates of seasonal nycteribiid parasitism of these hosts.

Methods

Live E. dupreanum and R. madagascariensis fruit bats were captured monthly in northern and central-eastern Madagascar from 2013-2020. Ectoparasites on all captured bats were counted and identified in the field, then collected into ethanol. Field identification of a subset of samples were confirmed via microscopy and DNA barcoding of the cytochrome C oxidase subunit 1 (COI) and 18S genes. The seasonal abundance of nycteribiid bat flies on both host bats was analyzed using generalized additive models, and the role of climate in driving this seasonality was assessed via cross-correlation analysis combined with generalized linear models. Phylogenetic trees were generated to compare COIand 18S sequences of Madagascar nycteribiid and streblid bat flies with available reference sequences from GenBank.

Results

Ectoparasites corresponding to four broad taxa (mites, ticks, fleas, and bat flies) were recovered from 628 of 873 E. dupreanum and 831 of 862 R. madagascariensis. E. dupreanum were most commonly parasitized by Cyclopodia dubia nycteribiids and R. madagascariensis by Eucampsipoda madagascariensis nycteribiids or Megastrebla wenzeli streblids. We observed significant seasonality in nycteribiid abundance on both bat hosts, which varied by bat sex and was positively correlated with lagged temperature, precipitation, and humidity variables. Barcoding sequences recovered for all three bat fly species grouped with previously reported sequences, confirming morphological species identification. Our study contributes the first DNA barcodes of any kind reported for M. wenzeli and the first 18S barcodes for C. dubia.

Conclusion

This study explores the diversity and abundance of ectoparasite burdens in two Malagasy fruit bat species, highlighting the importance of seasonal ecology and the influence of climate variables on parasitism, which correlates with resource availability.

A Five-Year Study on Infestation and Abundance of Bat Flies (Hippoboscoidea: Streblidae) Under Severe Dry Season Conditions in the Tropical Dry Forest of Yucatan, Mexico

In Mexico, few studies have explored how environmental conditions in tropical dry forests (TDF) influence bat fly load even though, according to climate change scenarios, this ecosystem will experience a drier and warmer climate. Such an extension of the dry season in these ecosystems could have dramatic consequences for biodiversity, particularly in regions with plains where animals do not have elevational climate shifts. The present study therefore evaluates the effect of prevailing environmental conditions during 2015-2019, as well as host body conditions, on the infestation and abundance of bat-specific ectoparasites and the composition and bat fly load in the dry season of a TDF in Yucatan. Since Yucatan has an essentially flat and low-lying topography, organisms cannot escape from the predicted extreme conditions with elevational shifts. This region is therefore an excellent location for assessment of the potential effects of warming. We collected 270 bat flies from 12 species. Three streblid species (Nycterophilia parnelli Wenzel, Trichobius johnsonae Wenzel, and Trichobius sparsus Kessel) are new records for Yucatan. Our overview of the dry season bat ectoparasite loads reveals low values of richness and prevalence, but high aggregation. Our models detected significant differences in ectoparasite infestation and abundance over the years, but the environmental and body host condition variables were unrelated to these. We report that pregnant females are parasitized to a greater extent by bat flies during the dry season, which generally represents the season of most significant nutritional stress.

Context-specific variation and repeatability in behavioral traits of bent-wing bats

Animals may show consistent among-individual behavioral differences over time and in different contexts, and these tendencies may be correlated to one another and emerge as behavioral syndromes. The cross-context variation in these behavioral tendencies, however, is rarely explored with animals in contexts associated with different locomotion modes. This study assessed the variation and repeatability in behavioral traits of bent-wing bats Miniopterus fuliginosus in southern Taiwan, and the effects of contextual settings associated with locomotion mode. The bats were sampled in the dry winter season, and their behaviors were measured in hole-board box (HB) and tunnel box (TB) tests, both suited for quadrupedal movements of the bats, and flight-tent (FT) tests that allowed for flying behaviors. The bats in the FT tests showed more interindividual and between-trial behavioral variation than those in the HB and TB tests. Nearly all of the behaviors in the TB and FT tests, but only half of those in the HB tests, showed medium to high repeatability. These repeatable behaviors were grouped into distinct behavioral traits of boldness, activity, and exploration, which were correlated to one another across contexts. In addition, we observed a consistently higher correlation between behavioral categories across the HB and TB contexts than between either of these contexts and the FT context. The results indicate consistent among-individual behavioral differences across time and contexts in wildly caught bent-wing bats. The findings of behavioral repeatability and cross-context correlations also indicate context-dependent variation and suggest that test devices which allow for flight behaviors, such as flight tents or cages, may provide a more suitable setting for measuring the behaviors and animal personalities of bats, particularly for those species that display less or little quadrupedal movements.