Hibernating vesper bats are a weak source for biomonitoring of coronaviruses

Background

Our study explores the role of bats as reservoirs of coronaviruses.

Methods

We conducted virological screening of bats hibernating in military bunkers at the Natura 2000 site "Nietoperek" in Western Poland collecting oral and anal swab samples from 138 bats across six species to apply a combination of pan-coronavirus and SARS-CoV-2 specific PCR assays.

Results

Only one anal swab tested positive for coronavirus. No SARS-CoV-2 was detected in any of the samples. The low prevalence of coronavirus in the studied colony contrasts with higher rates found in other regions and may be influenced by hibernation.

Conclusions

Hibernating bats may show a low prevalence of coronavirus, potentially due to the hibernation process itself. This finding indicates that hibernating bats may not be the most optimal subjects for screening zoonotic pathogens. However, biomonitoring of bats for emerging and reemerging diseases is recommended for comprehensive epidemiological insights.

Absence of lunar phobia in European swarming vespertilionid bats

"Lunar phobia" in bats has been widely discussed since its description in tropical bats in 1978. The phenomenon has been frequently contested and supported and was first reported in European bats in 2020. Our study seeks to clarify the debate by describing the relationship between the activity of selected swarming vespertilionid bats (Family: Vespertilionidae) and moonlight levels. To verify a potential connection to the latter, a swarming dataset was analysed in respect of estimated moonlight illumination. Moonlight estimates were based on geographical location and several lunar parameters, to accurately characterise the non-linear relationship between moon phase and illumination (lux). The swarming data consisted of 32 netting and 14 echolocation recording sessions collected between August and October 2014 and 2015. Our data included 3,265 netted bats from 13 species and 15,919 bat calls from 10 confirmed species. Data was collected at the large Central European hibernation/swarming site - Natura 2000 PLH080003 "Nietoperek" in western Poland (N 52.394400, E 15.480600). Generalised linear mixed models (GLMMs) determined insignificant relationships between bats and moonlight illumination. Our analysis confirms an absence of impact of moonlight intensity on swarming bats and thereby rejects the lunar phobia phenomena in at least six insectivorous bat species (Myotis myotis, M. daubentonii, M. nattereri, M. bechsteinii, Barbastella barbastellus, Plecotus auritus) swarming in the autumn.

Trophic relationship between Salix flowers, Orthosia moths and the western barbastelle

We present the results of a study which describes the relationship between the western barbastelle Barbastella barbastellus a highly specialised moth predator, and its prey-moths of the genus Orthosia, another selective animal known to converge around a dominant producer of pollen and nectar in early spring-willow trees Salix sp. In order to describe this trophic relationship, we conducted acoustic recordings at five paired sites (willow/control tree) in proximity to known barbastelle hibernation sites (Natura 2000: PLH080003 and PLH200014) beginning in mid-March 2022 after the first willow blossom sighting. Our study confirms a relationship between willow trees and barbastelles during early spring, as their activity around them was significantly higher than control sites. We also explore the activity of barbastelles over time, finding that activity levels around willows significantly decrease from the night of the first recorded bat, while the abundance of non-moth specialist bats remains consistent. Short-time importance (directly after hibernation) of willows for a moth specialist bat is probably due to other species blossom, attracting alternative prey, and in consequence-the bat. This newly described relationship should influence current conservation measures aimed at barbastelles.

First record of polydactyly for a European bat, Myotis daubentonii (Chiroptera, Vespertilionidae)

Despite being one of the most common congenital hand abnormalities in humans, polydactyly remains extremely rare in bats. To date, it has been observed only in two insectivorous families in North America (Molossidae and Vespertilionidae) and a single case for the New World fruit bats (Phyllostomidae). We report the first case of polydactyly in a European bat – a Myotis daubentonii (Vespertilionidae), with eight toes. The bat was found alive, hibernating in the Natura 2000 site (PLH080003 “Nietoperek”) in Poland.

Active surveillance for antibodies confirms circulation of lyssaviruses in Palearctic bats

BACKGROUND

Palearctic bats host a diversity of lyssaviruses, though not the classical rabies virus (RABV). As surveillance for bat rabies over the Palearctic area covering Central and Eastern Europe and Siberian regions of Russia has been irregular, we lack data on geographic and seasonal patterns of the infection.

RESULTS

To address this, we undertook serological testing, using non-lethally sampled blood, on 1027 bats of 25 species in Bulgaria, the Czech Republic, Poland, Russia and Slovenia between 2014 and 2018. The indirect enzyme-linked immunosorbent assay (ELISA) detected rabies virus anti-glycoprotein antibodies in 33 bats, giving an overall seroprevalence of 3.2%. Bat species exceeding the seroconversion threshold included Myotis blythii, Myotis gracilis, Myotis petax, Myotis myotis, Murina hilgendorfi, Rhinolophus ferrumequinum and Vespertilio murinus. While Myotis species (84.8%) and adult females (48.5%) dominated in seropositive bats, juveniles of both sexes showed no difference in seroprevalence. Higher numbers tested positive when sampled during the active season (10.5%), as compared with the hibernation period (0.9%). Bat rabies seroprevalence was significantly higher in natural habitats (4.0%) compared with synanthropic roosts (1.2%). Importantly, in 2018, we recorded 73.1% seroprevalence in a cave containing a M. blythii maternity colony in the Altai Krai of Russia.

CONCLUSIONS

Identification of such "hotspots" of non-RABV lyssavirus circulation not only provides important information for public health protection, it can also guide research activities aimed at more in-depth bat rabies studies.

A Culture-Based ID of Micromycetes on the Wing Membranes of Greater Mouse-Eared Bats (Myotis myotis) from the "Nietoperek" Site (Poland)

Bats play important functions in ecosystems and many of them are threatened with extinction. Thus, the monitoring of the health status and prevention of diseases seem to be important aspects of welfare and conservation of these mammals. The main goal of the study was the identification of culturable fungal species colonizing the wing membranes of female greater mouse-eared bat (Myotis myotis) during spring emergence from the "Nietoperek" underground hibernation site by the use of genetic and phenotypic analyses. The study site is situated in Western Poland (52°25' N, 15°32' E) and is ranked within the top 10 largest hibernation sites in the European Union. The number of hibernating bats in the winter exceeds 39,000 individuals of 12 species, with M. myotis being the most common one. The wing membranes of M. myotis were sampled using sterile swabs wetted in physiological saline (0.85% NaCl). Potato dextrose agar (PDA) plates were incubated in the dark at 8, 24 and 36 ± 1 °C for 3 up to 42 days. All fungi isolated from the surface of wing membranes were assigned to 17 distinct fungal isolates belonging to 17 fungal species. Penicillium chrysogenum was the most frequently isolated species. Some of these fungal species might have a pathogenic potential for bats and other mammals. However, taking into account habitat preferences and the life cycle of bats, it can be assumed that some fungi were accidentally obtained from the surface of vegetation during early spring activity. Moreover, Pseudogymnoascus destructans (Pd)-the causative agent of the White Nose Syndrome (WNS)-was not found during testing, despite it was found very often in M. myotis during previous studies in this same location.