The effect of water contamination and host-related factors on ectoparasite load in an insectivorous bat

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.

Increased bat hunting at polluted streams suggests chemical exposure rather than prey shortage

Streams and their riparian areas are important habitats and foraging sites for bats feeding on emergent aquatic insects. Chemical pollutants entering freshwater streams from agricultural and wastewater sources have been shown to alter aquatic insect emergence, yet little is known about how this impacts insectivorous bats in riparian areas. In this study, we investigate the relationships between the presence of wastewater effluent, in-stream pesticide toxicity, the number of emergent and flying aquatic insects, and the activity and hunting behaviour of bats at 14 streams in southwestern Germany. Stream sites were located in riparian forests, sheltered from direct exposure to pollutants from agricultural and urban areas. We focused on three bat species associated with riparian areas: Myotis daubentonii, M. cf. brandtii, and Pipistrellus pipistrellus. We found that streams with higher pesticide toxicity and more frequent detection of wastewater also tended to be warmer and have higher nutrient and lower oxygen concentrations. We did not observe a reduction of insect emergence, bat activity or hunting rates in association with pesticide toxicity and wastewater detections. Instead, the activity and hunting rates of Myotis spp. were higher at more polluted sites. The observed increase in bat hunting at more polluted streams suggests that instead of reduced prey availability, chemical pollution at the levels measured in the present study could expose bats to pollutants transported from the stream by emergent aquatic insects.

Modularity in host-parasite mixed networks: interaction configuration shifts based on human perturbation and parasitism form

Parasitism is an association based on host individual traits and environmental factors. The complexity of this type of interaction is often lost when studying species-by-species interaction networks. Here we analyze changes in modularity - a metric describing groups of nodes interacting much more frequently among themselves than they do with nodes of other modules, considering the host individual variation and the different forms of parasitism: ecto- and endo-parasitism. For this, we studied mixed networks: bipartite networks comprising host individuals and parasite species as two sets of nodes interacting with each other. We used a fish-parasite mixed network from a highly perturbed coastal river to understand how an anthropogenic perturbation gradient influences the modular structure of host-parasite networks. In addition, we tested how host individual traits drove module configuration within host-parasite mixed networks. Our results showed that different forms of parasitism respond differently to the environment: modularity in fish-ectoparasite networks increased with human perturbation, but modularity was not related to human perturbation in fish-endoparasite networks. In addition, mixed network modules were intrinsically related to individual variation, with host intensity of infection being the most important trait, regardless of the parasite's life form. The effect of total abundance over network structure indicates signs of changes in community equilibrium, with an increase in species with opportunistic behaviors. Module composition was also related to host fitness and body size, which were most predictive in more preserved and diverse river sections. Overall, our results indicate that host-parasite networks are sensitive to ecological gradients marked by human perturbation and that host individual fitness helps to determine network structure.

Helminth fauna of mouse-like rodents in the territory of Moscow City

Conditions of the urban environment have a significant impact on the ecology of animals, including helminth communities. The response of the helminth community to ecological imbalance and their adaptation to life in the urban environment remain an urgent problem in parasitology. In this study, we aimed to compare the species diversity and distribution of helminths in urban forest parks with varying degrees of anthropogenic pressure. In urbanized territories of 5 locations of the city of Moscow, the infestation parameters of model rodent species were assessed in comparison with a natural, slightly disturbed territory (the scientific and experimental base “Chernogolovka”). In the four most common rodent species (n = 158), Apodemus agrarius, Sylvaemus uralensis, Microtus arvalis, and Clethrionomys glareolus, caught by Hero's traps, the gastrointestinal tract was removed, the number and species of parasites were determined, and the infestation was assessed by 3 parameters. The species composition of helminths and the presence of three parasite classes in the composition of the helminth fauna of the studied species expectedly corresponded to the characteristics of disturbed areas. In addition, a change in the dominant helminth species (H. polygyrus to H. Spumosa) was noted, which indicated a significant influence of the helminth fauna of synanthropic species on the composition of the parasite communities of wild species living in the city. Our study contributes to the accumulation of information on the species composition of endoparasite communities of murine rodents in the city of Moscow, which is important for compiling an up-to-date epidemiological picture of the city.

Ectoparasites and Pathogens of Kuhl's Pipistrelle Pipistrellus kuhlii (Kuhl, 1817) (Chiroptera: Vespertilionidae): Our Own and Published Data Review

Here we report the results of our own survey and literary published data on the ectoparasite fauna and pathogens of the alien bat species, the Kuhl's pipistrelle Pipistrellus kuhlii (Kuhl, 1817) (Chiroptera: Vespertilionidae). This bat is a host of 36 species of parasitic mites, ticks and insects (including accidental findings) and 13 species of pathogens (protozoa, bacteria, viruses). The flea Ischnopsyllus variabilis is re-corded on this host for the first time. We have found that outside of the host ancestral range, the core of the bat parasite fauna is significantly different due to the loss of host species-specific ectoparasites. Particularly, in Russia, only 6 species of parasitic arthropods have been recorded for Kuhl's pipistrelle and all of them are host genus-specific. At the same time, the features of ecology and occasional finds of extrinsic parasites allow to suggest that P. kuhlii has wide contacts with animals which are the reservoirs of zoonotic infec-tions, that in combination with the fact of isolation of several pathogens from this species (including two coronaviruses) points to a possible medical importance of Kuhl's pipistrelle.