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35 result(s) for "Bartonička, Tomáš"
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Bat aggregational response to pest caterpillar emergence
Moths (Lepidoptera) are major agricultural and forest pests in many parts of the world, including Europe, with many causing great economic damage to crops, horticultural plants, stored items, and wool products. Here, we focus on two ecologically similar inchworms, Operophtera brumata and Erannis defoliaria , known for their high foliage consumption during the spring emergence of caterpillars. We hypothesise that bats could play a role in reducing pests such as caterpillars by switching to this abundant emerging prey. At two infested and one control forest sites, caterpillars were sampled during spring to determine levels of infestation. At the same time, bat flight activity was monitored during the peak in caterpillar abundance. During the spring caterpillar outbreak, we collected faecal samples of forest-dwelling bats capable of using gleaning. The majority of samples were positive for our focus species, being 51.85% for O. brumata and 29.63% for E. defoliaria faecal samples. The foraging activity of two gleaning bats, Myotis nattereri and Myotis bechsteinii , increased at both infested sites, but not at the control site, during caterpillar emergence, as did foraging of Plecotus auritus/austriacus , which used both gleaning and aerial hawking. We conclude that both specialists and occasional gleaners, which prefer different prey but are able to switch their foraging strategies, aggregate at sites during pest emergence and, as such, our results confirm the high potential of bats to reduce numbers of pest species such as caterpillars.
Ungulate-vehicle crashes peak a month earlier than 38 years ago due to global warming
Global change has manifested itself as climate warming in Central Europe in recent decades. Average daily air temperatures increased by an average of 2 °C between 1982 and 2018. Air temperature changes have affected the timing of the vegetation periods (phenophases) and have also influenced the behaviour of animals. We worked with data on wildlife-vehicle crashes (WVC) recorded by the Czech Police in the period 1982–2019. Three peaks can usually be observed (spring, summer, and autumn) in the WVC time series. Eighty percent of these records involved roe deer (Capreolus capreolus). Such a high ratio allowed us to assume that any significant changes detected in WVC will be predominantly related to roe deer. We discovered that roe deer mortality on roads occurs earlier at present in the spring than in the past. The spring peak has shifted almost a month to the beginning of the year compared to the situation 38 years ago. The changes in the respective summer and autumn peaks were not statistically significant. The results suggest the effect of climate change on roe deer behaviour through increasing air temperatures and shifting vegetation phenophases. Thus, an earlier onset of deer activity associated with territory delineation and expected higher movement activity can be indirectly determined by the analysis of the WVC time series. The observed shift in the spring WVC peak in the roe deer model reveals a shift in ungulate behavioural patterns that is not evident from other biological data and thus surprisingly offers a suitable study framework for determining the impacts of environmental change on animals.
Identification of Local Factors Causing Clustering of Animal-Vehicle Collisions
Effective measures reducing risk of animal-vehicle collisions (AVC) require defining high-risk locations on roads where AVCs occur. Previous studies examined factors explaining locations of individual AVCs; however, some AVCs can form hotspots (i.e., clusters of AVCs) that can be explained by local factors. We therefore applied a novel kernel density estimation (KDE) method to AVCs for the Czech Republic from October 2006 to December 2011 to identify AVCs hotspots along roads. Our main goal was to identify local factors and their effect on the non-random (clustered) occurrence of AVCs. The remaining solitary AVCs occurred randomly and are likely induced by other human factors on the global scale. The hotspot identification method followed by the selected data mining methods (KDE+ methods) identified factors causing local clustering of AVCs. Distance from forest (<350 m) or linear vegetation were important factors for estimating presence of clusters of AVCs; in open areas, AVC clusters were absent. Further research on effectiveness of measures reducing risk of AVC should focus on clusters of AVCs, not on the individual AVC. We recommend that state transportation agencies focus mitigation actions in forested areas.
Changes in body size and fertility due to artificial and natural feeding of laboratory common bed bugs (Heteroptera: Cimicidae)
Rearing common bed bugs (Cimex lectularius L.) and other hematophagous insects is essential for basic, medical, and pest-control research. Logistically, acquiring fresh blood can be a challenge, while biologically, the eventual effects of different rearing and blood preparation protocols on bed bug genotype and phenotype pose a risk of biased research results. Using bed bug populations that are either bat- (BL) or human-related (HL), we tested the short- and long-term effects of rearing bugs on live bats or human volunteers, or artificially on CPDA (citrate phosphate dextrose, adenine)-treated blood, measuring meal size, body size, and fertility. We found that artificial feeding did not affect meal size compared with feeding on natural hosts. Long-term rearing across many generations of HL on CPDA-preserved blood led to reduced body size and fertility compared with populations reared on human volunteers. Blood preservatives increased the proportion of sterile eggs even after a single feed. Finally, our results indicated that laboratory reared bed bugs were smaller, regardless of the blood source, than wild bugs. Similar effects of artificial feeding or laboratory rearing alone should be considered in future studies using bed bug cultures to choose an appropriate rearing protocol. With regard to switching between bat and human hosts, HL took smaller meals and BL had lower fertility when fed on bats than when fed on humans. We attribute these results to methodological constrains, specifically the inconsistency of bat feeding, rather than to host specialization. Nevertheless, BL can be easily reared using human blood and artificial feeding systems.
Morphological size determination of moths in bat faeces opens possibilities to prey quantification
High number of moth species are considered to be agricultural pests in their caterpillar stage. Birds and other arthropods often forage moths, but ecosystem services provided by temperate bats are just coming to light in past few years. Although there is no doubt that insectivorous bats forage upon adult stages of pest moths contributing to the quality and quantity of crops, it remains unclear how many prey items have foraged and therefore it is unclear if the amounts taken are sufficient for biocontrol. Molecular detection of pest moth imagoes in bat diet is a relatively new approach that only delivers present or absent data. Therefore, sorting contains of bat faeces using morphological size determination may lead to better prey quantification. As the number of consumed prey items determines the boundary between consumption and regulatory significance, we focused on (i) if indigestible moth body parts retrieved from faeces reflect the number of moths eaten, (ii) how size of indigestible moth body parts relates to the overall moth body size, and (iii) an accuracy of moth classification into size groups. Our results indicated that base frenulum (hook holding front and hinder wings together) width is the most suitable characteristic to determine body size of the moth, with a discrimination success exceeding 73% when placing the moth into one of four size categories. The size differentiation of prey within a faecal sample together with molecular identification and other semiquantitative methods allows for more precise quantification and could yet help confirm the importance of bats as biological control agents.
Disease alters macroecological patterns of North American bats
AIM: We investigated the effects of disease on the local abundances and distributions of species at continental scales by examining the impacts of white‐nose syndrome, an infectious disease of hibernating bats, which has recently emerged in North America. LOCATION: North America and Europe. METHODS: We used four decades of population counts from 1108 populations to compare the local abundances of bats in North America before and after the emergence of white‐nose syndrome to the situation in Europe, where the disease is endemic. We also examined the probability of local extinction for six species of hibernating bats in eastern North America and assessed the influence of winter colony size prior to the emergence of white‐nose syndrome on the risk of local extinction. RESULTS: White‐nose syndrome has caused a 10‐fold decrease in the abundance of bats at hibernacula in North America, eliminating large differences in species abundance patterns that existed between Europe and North America prior to disease emergence. White‐nose syndrome has also caused extensive local extinctions (up to 69% of sites in a single species). For five out of six species, the risk of local extinction was lower in larger winter populations, as expected from theory, but for the most affected species, the northern long‐eared bat (Myotis septentrionalis), extinction risk was constant across winter colony sizes, demonstrating that disease can sometimes eliminate numerical rarity as the dominant driver of extinction risk by driving both small and large populations extinct. MAIN CONCLUSIONS: Species interactions, including disease, play an underappreciated role in macroecological patterns and influence broad patterns of species abundance, occurrence and extinction.
2020 taxonomic update for phylum Negarnaviricota (Riboviria: Orthornavirae), including the large orders Bunyavirales and Mononegavirales
In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.
Olfactory discrimination between two cryptic species of bats Pipistrellus pipistrellus and P. pygmaeus
Absence of accuracy in species recognition can lead to inter-specific mating and hybridization. Aside from acoustic signals, bats can also use olfactory signals to search for mates. We compared the level of attractiveness of facial glands scents and urinary scents for discrimination in two cryptic bat species. Both sexes of two sympatric bat species Pipistrellus pipistrellus and P. pygmaeus were used as model. Possible sexual preferences using two olfactory signals were studied in a dual choice experiment in a glass Y-maze. Both sexes, without reference to the species, performed lower searching activity in tests with urinary scents than in the case of signals composed of scents of facial glands. Males of both species were able to discriminate and prefer the odour of conspecific females, with small proportion of disassortative choices. Females of both species did not have species-specific preferences. Absence of females' odour preferences and small proportion of males' disassortative choices can provide theoretical background for the existence of inter-species hybridization or point at more important role of acoustic signals in pre-mating behaviour.
White-nose syndrome pathology grading in Nearctic and Palearctic bats
While white-nose syndrome (WNS) has decimated hibernating bat populations in the Nearctic, species from the Palearctic appear to cope better with the fungal skin infection causing WNS. This has encouraged multiple hypotheses on the mechanisms leading to differential survival of species exposed to the same pathogen. To facilitate intercontinental comparisons, we proposed a novel pathogenesis-based grading scheme consistent with WNS diagnosis histopathology criteria. UV light-guided collection was used to obtain single biopsies from Nearctic and Palearctic bat wing membranes non-lethally. The proposed scheme scores eleven grades associated with WNS on histopathology. Given weights reflective of grade severity, the sum of findings from an individual results in weighted cumulative WNS pathology score. The probability of finding fungal skin colonisation and single, multiple or confluent cupping erosions increased with increase in Pseudogymnoascus destructans load. Increasing fungal load mimicked progression of skin infection from epidermal surface colonisation to deep dermal invasion. Similarly, the number of UV-fluorescent lesions increased with increasing weighted cumulative WNS pathology score, demonstrating congruence between WNS-associated tissue damage and extent of UV fluorescence. In a case report, we demonstrated that UV-fluorescence disappears within two weeks of euthermy. Change in fluorescence was coupled with a reduction in weighted cumulative WNS pathology score, whereby both methods lost diagnostic utility. While weighted cumulative WNS pathology scores were greater in the Nearctic than Palearctic, values for Nearctic bats were within the range of those for Palearctic species. Accumulation of wing damage probably influences mortality in affected bats, as demonstrated by a fatal case of Myotis daubentonii with natural WNS infection and healing in Myotis myotis. The proposed semi-quantitative pathology score provided good agreement between experienced raters, showing it to be a powerful and widely applicable tool for defining WNS severity.
Male diet affects female fitness and sperm competition in human- and bat-associated lineages of the common bedbug, Cimex lectularius
Sperm performance can vary in ecologically divergent populations, but it is often not clear whether the environment per se or genomic differences arising from divergent selection cause the difference. One powerful and easily manipulated environmental effect is diet. Populations of bedbugs ( Cimex lectularius ) naturally feed either on bat or human blood. These are diverging genetically into a bat-associated and a human-associated lineage. To measure how male diet affects sperm performance, we kept males of two HL and BL populations each on either their own or the foreign diet. Then we investigated male reproductive success in a single mating and sperm competition context. We found that male diet affected female fecundity and changed the outcome of sperm competition, at least in the human lineage. However, this influence of diet on sperm performance was moulded by an interaction. Bat blood generally had a beneficial effect on sperm competitiveness and seemed to be a better food source in both lineages. Few studies have examined the effects of male diet on sperm performance generally, and sperm competition specifically. Our results reinforce the importance to consider the environment in which sperm are produced. In the absence of gene flow, such differences may increase reproductive isolation. In the presence of gene flow, however, the generally better sperm performance after consuming bat blood suggests that the diet is likely to homogenise rather than isolate populations.