Host social organization and mating system shape parasite transmission opportunities in three European bat species

The effect of group size on sleep in a neotropical bat, Artibeus jamaicensis

Sleep is associated with many costs, but is also important to survival, with a lack of sleep impairing cognitive function and increasing mortality. Sleeping in groups could alleviate sleep-associated costs, or could introduce new costs if social sleeping disrupts sleep. Working with the Jamaican fruit bat (Artibeus jamaicensis), we aimed to: (1) describe sleep architecture, (2) assess how sleeping in groups affects sleep, and (3) quantify total sleep time and identify rapid eye movement (REM) sleep using behavioral indicators that complement physiological evidence of sleep. Twenty-five adult bats were captured in Panama and recorded sleeping in an artificial roost enclosure. Three bats were fitted with an electromyograph and accelerometer and video recorded sleeping alone in controlled laboratory settings. The remaining 22 bats were assigned to differing social configurations (alone, dyad, triad, and tetrad) and video recorded sleeping in an outdoor flight cage. We found that sleep was highly variable among individuals (ranging from 2 h 53 min to 9 h 39 min over a 12-h period). Although we did not detect statistically significant effects and our sample size was limited, preliminary trends suggest that male bats may sleep longer than females, and individuals sleeping in groups may sleep longer than individuals sleeping alone. We also found a high correspondence between total sleep time quantified visually and quantified using actigraphy (with a 2-min immobility threshold) and identified physiological correlates of behaviorally-defined REM. These results serve as a starting point for future work on the ecology and evolution of sleep in bats and other wild mammals.

Season and host-community composition inside roosts may affect host-specificity of bat flies

Bat flies are one of the most abundant ectoparasites of bats, showing remarkable morphological adaptations to the parasitic habit, while the relationship with their hosts is characterized by a high level of specificity. By collecting bat flies from live hosts, our intention was to elucidate the seasonal differences in bat fly occurrence and to describe factors regulating the level of incipient host specificity. Our results indicate that the prevalence and the intensity of infestation is increasing from spring to autumn for most host species, with significant differences among different fly species. Males showed higher infestation levels than females in autumn, suggesting a non-random host choice by flies, targeting the most active host sex. Bat-bat fly host specificity shows seasonal changes and host choice of bat flies are affected by the seasonal differences in hosts' behavior and ecology, the intensity of infestation and the species composition of the local host community. Nycteribiid bat flies showed lower host specificity in the swarming (boreal autumn) period, with higher prevalence recorded on non-primary hosts. Choosing a non-primary bat host may be an adaptive choice for bat flies in the host's mating period, thus increasing their dispersive ability in a high activity phase of their hosts.

Sex-biased, but not plumage color-based, prevalence of haemosporidian parasites in free-range chickens

Previous studies found a relationship between blood parasite infection and bird gender, with higher prevalence in males. Some studies also found a relationship between host plumage color and parasitic infection, while others did not. Here, we investigated the blood parasite prevalence in correlation with sex and plumage color in free-range chickens (Gallus gallus domesticus) in China. We analyzed a total of 297 blood samples, out of which 234 chickens tested positive for haemosporidian parasites, with 78.5% parasite prevalence. Out of 139 males, 118 tested positive with 84.8% parasite prevalence while 116 of 158 female samples tested positive (73.4%). Leucocytotozoon was the most frequent genus isolated (193 infected individuals /234 birds), followed by Plasmodium (41 infected individuals/234 birds), with no Haemoproteus parasites being detected. There were no significant differences in the body parameters and chicken color plumages with regards to the infection status. Our study indicated that blood parasite infection was significantly different between male and female chickens, with infection prevalent in males.

Ectoparasitic flies of bats (Mammalia: Chiroptera) in urban green areas of northeastern Brazil

In urban and degraded areas, ectoparasite abundance can be affected by increasing human population density and habitat fragmentation. This study aimed to characterize the ectoparasitic fly community associated with bats in the urban green areas of Sergipe, Brazil. Campaigns were conducted monthly, for two consecutive nights, between September 2019 and February 2021. To capture the bats, ten mist nets were set up inside and at the edge of the habitat fragments. All ectoparasites found were removed from the bats and stored in 70% alcohol. The specificity index, parasitological rates, and level of parasite aggregation were calculated, and the influence of host sex and seasonality on parasitological rates were verified for the most parasitized bats. The collected ectoparasites corresponded to the families Nycteribiidae (S = 1; n = 26) and Streblidae (S = 13; n = 849), with Trichobius costalimai and Medistopoda aranea being the most abundant species. For some interactions, there was an influence of host sex on the prevalence rates, with the highest number of parasites being found on females, which can be explained by their greater susceptibility to parasitism owing to their long stay in roosts. The seasonality influenced the parasitological rates, and opposing patterns (from what was expected) were observed for some interactions; this influence may be due to the biological differences between parasite species. This study provides relevant data on this interaction, especially for urban areas in northeastern Brazil, expanding the number of studies in the State of Sergipe and promoting future studies.

Does latitudinal migration represent an advantage in the decrease of ectoparasitic loads in Leptonycteris yerbabuenae (Chiroptera)?

Latitudinal migration increases fitness of migrants by allowing them to exploit favorable conditions in nonadjacent geographic regions. Other consequences also may follow, such as interactions with parasites. Migrants may have lower parasite prevalence and abundance than resident individuals because of their ability to abandon infested areas or due to mortality of highly infested hosts. To further understand whether variation in ectoparasite loads is influenced by migration, we investigated whether prevalence and abundance of two species of obligate ectoparasites, the wing mite Periglischrus paracaligus (Mesostigmata: Spinturnicidae) and the bat fly Nycterophilia coxata (Diptera: Streblidae, Nycterophiliinae), of the lesser long-nosed bat, Leptonycteris yerbabuenae, varied between migratory and resident populations throughout their range in Mexico. We examined the presence or absence of migratory behavior, as well as sex and reproductive status of the host because ectoparasitism differentially affects the sexes. Our results showed that the prevalence of both ectoparasites did not vary between migrant and resident females or males, but abundance of the wing mite P. paracaligus was lower in migrant females compared with resident females, with an important influence from the reproductive status of the host. A partial negative relationship between ectoparasite loads and latitudinal migration therefore was demonstrated.

Reproduction of East-African bats may guide risk mitigation for coronavirus spillover

BACKGROUND

Bats provide important ecosystem services; however, current evidence supports that they host several zoonotic viruses, including species of the Coronaviridae family. If bats in close interaction with humans host and shed coronaviruses with zoonotic potential, such as the Severe Acute Respiratory Syndrome virus, spillover may occur. Therefore, strategies aiming to mitigate potential spillover and disease emergence, while supporting the conservation of bats and their important ecological roles are needed. Past research suggests that coronavirus shedding in bats varies seasonally following their reproductive cycle; however, shedding dynamics have been assessed in only a few species, which does not allow for generalization of findings across bat taxa and geographic regions.

METHODS

To assess the generalizability of coronavirus shedding seasonality, we sampled hundreds of bats belonging to several species with different life history traits across East Africa at different times of the year. We assessed, via Bayesian modeling, the hypothesis that chiropterans, across species and spatial domains, experience seasonal trends in coronavirus shedding as a function of the reproductive cycle.

RESULTS

We found that, beyond spatial, taxonomic, and life history differences, coronavirus shedding is more expected when pups are becoming independent from the dam and that juvenile bats are prone to shed these viruses.

CONCLUSIONS

These findings could guide policy aimed at the prevention of spillover in limited-resource settings, where longitudinal surveillance is not feasible, by identifying high-risk periods for coronavirus shedding. In these periods, contact with bats should be avoided (for example, by impeding or forbidding people access to caves). Our proposed strategy provides an alternative to culling - an ethically questionable practice that may result in higher pathogen levels - and supports the conservation of bats and the delivery of their key ecosystem services.

Between roost contact is essential for maintenance of European bat lyssavirus type-2 in Myotis daubentonii bat reservoir: 'The Swarming Hypothesis'

Many high-consequence human and animal pathogens persist in wildlife reservoirs. An understanding of the dynamics of these pathogens in their reservoir hosts is crucial to inform the risk of spill-over events, yet our understanding of these dynamics is frequently insufficient. Viral persistence in a wild bat population was investigated by combining empirical data and in-silico analyses to test hypotheses on mechanisms for viral persistence. A fatal zoonotic virus, European Bat lyssavirus type 2 (EBLV-2), in Daubenton’s bats (Myotis daubentonii) was used as a model system. A total of 1839 M. daubentonii were sampled for evidence of virus exposure and excretion during a prospective nine year serial cross-sectional survey. Multivariable statistical models demonstrated age-related differences in seroprevalence, with significant variation in seropositivity over time and among roosts. An Approximate Bayesian Computation approach was used to model the infection dynamics incorporating the known host ecology. The results demonstrate that EBLV-2 is endemic in the study population, and suggest that mixing between roosts during seasonal swarming events is necessary to maintain EBLV-2 in the population. These findings contribute to understanding how bat viruses can persist despite low prevalence of infection, and why infection is constrained to certain bat species in multispecies roosts and ecosystems.

Bats and ticks: host selection and seasonality of bat-specialist ticks in eastern Europe

Background

Parasites may actively seek for hosts and may use a number of adaptive strategies to promote their reproductive success and host colonization. These strategies will necessarily influence their host specificity and seasonality. Ticks are important ectoparasites of vertebrates, which (in addition to directly affecting their hosts) may transmit a number of pathogens. In Europe, three hard tick species (Ixodidae: Ixodes ariadnae, I. simplex and I. vespertilionis) and at least two soft tick species (Argasidae: Argas transgariepinus and A. vespertilionis) are specialized for bats.

Methods

Here we report data on the host range of these ticks and the seasonality of tick infestation on wild caught bats in south-east Europe. We collected 1803 ticks from 30 species of bats living in underground shelters (caves and mines) from Romania and Bulgaria. On the basis of tick–host associations, we tested several hypotheses on host–parasite evolutionary adaptations regulating host specificity, seasonality and sympatric speciation.

Results

We observed significant differences in host specificity and seasonality of abundance between the morphologically different bat specialist ticks (I. simplex and I. vespertilionis) likely caused by their host choice and their respective host-seeking behavior. The two highly generalist, but morphologically similar tick species (I. ariadnae and I. vespertilionis) showed temporal differences in occurrence and activity, thus exploiting significantly different host communities while occurring in geographical sympatry.

Conclusions

We conclude that bat-specialist ticks show a wide range of adaptations to their hosts, with differences in specificity, seasonality of occurrence, the prevalence and intensity of infestation and all these contribute to a successful division of temporal niches of ticks sharing morphologically similar hosts occurring in geographical sympatry.

Beta diversity of gastrointestinal helminths in two closely related South African rodents: species and site contributions

A fundamental aim of parasite ecology is to understand the mechanisms behind spatial variation in diversity and structure of parasite assemblages. To understand the contribution of individual parasite species and their assemblages to spatial variation in parasite communities, we examined species contributions to beta diversity (SCBD) and local contributions to beta diversity (LCBD) of parasitic gastrointestinal helminths (nematodes and cestodes) in two closely related rodents, Rhabdomys dilectus and Rhabdomys pumilio, from 20 localities across South Africa. Although the two Rhabdomys spp. are morphologically similar, they differ substantially in body size, habitat preference, and sociality. We asked whether the variation in life history traits and infection parameters are associated with SCBD of helminths and whether variation in environmental factors, host population density, and species richness of host communities are associated with LCBD of component assemblages of helminths. We also considered spatial factors to test whether LCBD of helminth assemblages demonstrate geographic structure. We found that the contribution of helminth species parasitic in both hosts to beta diversity significantly increased with characteristic prevalence of these species, whereas mean abundance, type of life cycle, and location in the host's gut had no effect on SCBD. The LCBD of helminth assemblages showed a significant positive correlation with environmental factors in both host species. Our results suggest that predictors of variation in SCBD and LCBD may substantially differ between parasites with different infection parameters and/or parasite communities at different hierarchical scales.

Very low rate of multiple paternity detected in clutches of a wild agamid lizard

Genetic mating systems described for squamate reptiles range from primarily monogamous to completely polygynandrous. The presence of female multiple mating is almost ubiquitous among squamates and even occurs, albeit at a low rate, in socially monogamous species. Here we examine the genetic mating system of the territorial tawny dragon lizard (Ctenophorus decresii). Paternity was assigned to captive-born hatchlings using eight microsatellite loci, revealing a 4% rate of multiple paternity. One-quarter of males sired more than one clutch, although multiple mating by males is likely underestimated. The rate of multiple paternity in C. decresii represents one of the lowest among squamates and may be a result of successful male territoriality. However, the observed low rate of multiple paternity does not eliminate the possibility of widespread female multiple mating due to the potential for sperm storage and sperm competition. We conclude that the tawny dragon lizard employs a predominantly polygynous genetic mating system.