Czech Arachnological Society

Macroecologists seek to identify drivers of community turnover (β-diversity) through broad spatial scales. However, the influence of local habitat features in driving broad-scale β-diversity patterns remains largely untested, owing to the objective challenges of associating local-scale variables to continental-framed datasets. We examined the relative contribution of local- versus broad-scale drivers of continental β-diversity patterns, using a uniquely suited dataset of cave-dwelling spider communities across Europe (35–70° latitude). Generalized dissimilarity modelling showed that geographical distance, mean annual temperature and size of the karst area in which caves occurred drove most of β-diversity, with differential contributions of each factor according to the level of subterranean specialization. Highly specialized communities were mostly influenced by geographical distance, while less specialized communities were mostly driven by mean annual temperature. Conversely, local-scale habitat features turned out to be meaningless predictors of community change, which emphasizes the idea of caves as the human accessible fraction of the extended network of fissures that more properly represents the elective habitat of the subterranean fauna. To the extent that the effect of local features turned to be inconspicuous, caves emerge as experimental model systems in which to study broad biological patterns without the confounding effect of local habitat features.

Background

Spiders (Arachnida: Araneae) are widespread in subterranean ecosystems worldwide and represent an important component of subterranean trophic webs. Yet, global-scale diversity patterns of subterranean spiders are still mostly unknown. In the frame of the CAWEB project, a European joint network of cave arachnologists, we collected data on cave-dwelling spider communities across Europe in order to explore their continental diversity patterns. Two main datasets were compiled: one listing all subterranean spider species recorded in numerous subterranean localities across Europe and another with high resolution data about the subterranean habitat in which they were collected. From these two datasets, we further generated a third dataset with individual geo-referenced occurrence records for all these species.

New information

Data from 475 geo-referenced subterranean localities (caves, mines and other artificial subterranean sites, interstitial habitats) are herein made available. For each subterranean locality, information about the composition of the spider community is provided, along with local geomorphological and habitat features. Altogether, these communities account for > 300 unique taxonomic entities and 2,091 unique geo-referenced occurrence records, that are made available via the Global Biodiversity Information Facility (GBIF) (Mammola and Cardoso 2019). This dataset is unique in that it covers both a large geographic extent (from 35° south to 67° north) and contains high-resolution local data on geomorphological and habitat features. Given that this kind of high-resolution data are rarely associated with broad-scale datasets used in macroecology, this  dataset has high potential for helping researchers in tackling a range of biogeographical and macroecological questions, not necessarily uniquely related to arachnology or subterranean biology.

Species-specific patterns of courtship behaviour are often used in wolf spider species delimitation. However, differences in courtship patterns are rarely assessed in an evolutionary context. The wolf spider genus Alopecosa comprises 150 species, for which the distribution and mating periods commonly overlap. We analysed the courtship and copulatory behaviour of 14 European Alopecosa species that are traditionally classified into four sibling species complexes (groups) and sequenced one mitochondrial (COI) and two nuclear genes (28S, H3) to reconstruct their phylogenetic relationships. The courtship behaviour of Alopecosa wolf spiders includes 17 elements, involving palpal, pedal, opisthosomal and whole-body movements. The observed courtship and copulation behaviours exhibit both conserved elements and species-specific combinations of traits. The results of the phylogenetic analyses were largely incongruent with the traditional, morphology-based grouping. Species from the ‘pulverulenta’ group formed a monophylum, although members of the ‘striatipes’ and ‘fabrilis’ groups were recovered as para- or polyphyletic. Furthermore, monophyly of Alopecosa was not recovered. We provide a checklist of species-specific traits presented during courtship and copulation that can be used to identify sibling species complexes.

A few specimens (both adults and larvae) of the arachnophilous stilt bug Metacanthus annulosus Fieber, 1859 were found in a web of the giant house spider Eratigena atrica (C. L. Koch, 1843) in Brno (Czech Republic). This is the first host record, and confirmation of the species’ arachnophily, in Central Europe.

Metacanthus (Cardopostethus) annulosus Fieber, 1859 is a rarely collected species of stilt bug (Hemiptera: Heteroptera: Berytidae), distributed in the Mediterranean region and the Pannonian Basin (Péricart 2001,  Morkel 2007, Vašíček et al. 2018). It is an arachnophilous species living in spider webs, where it feeds on trapped arthropods (Štys et al. 2003, Morkel 2007). So far, these stilt bugs have been found in the funnel-webs of spiders of the genus Agelena (Araneae: Agelenidae). In eastern parts of the Mediterranean area (Anatolia, the Cyclades) the host spider was identified as Agelena orientalis (Štys et al. 2003, Morkel 2007). Agelena orientalis does not occur in Croatia (Nentwig et al. 2018), where M. annulosus was found in the webs of another, still unidentified, species of Agelena s. lat. (Vašíček et al. 2018). In Central Europe, M. annulosus has so far only been collected very rarely, and details of its ecology have been largely unknown (Rabitsch 2004, 2009, Vašíček et al. 2018).

Varroa destructor is the major cause of honey bee (Apis mellifera) colony losses. Mite control is limited to several miticides. The overuse of tau-fluvalinate has resulted in resistance via a knockdown resistance (kdr) mutation in the sodium channel gene Na V Chs (L925V/I/M). In this study, we used the discriminating concentration of tau-fluvalinate (0.25 μg/mL) to detect the resistance of mites in a bioassay. Further, we verified the presence of the kdr mutation in mites from the bioassay via PCR amplification of a fragment of the voltage-gated sodium channel gene (Na V Ch), restriction fragment length polymorphisms (RFLPs), and ensitometry analyses in pools of surviving or dead mites. Resistance values corresponding to the densitometry of the resistant allele were related to mite survival. In the vial test, the survival of the control group was significantly higher (70.4%) than that of the tau-fluvalinate-treated group (34.3%). Mite survival in the vial test was significantly correlated with the mean proportion of resistance values. Individuals that died after tau-fluvalinate application exhibited an average resistance value of 0.0783, whereas individuals that survived exhibited an average resistance of 0.400. The concentration of tau-fluvalinate in the vials was checked using high performance liquid chromatography under different temperatures and exposure times, and indicates that the stability of tau-fluvalinate stored in the refrigerator (4 ± 1 °C) is at least 14 days. PCR–RFLP of the Na V Ch gene fragment verified that the vial test is a suitable, rapid, and cost-effective method for the identification of tau-fluvalinate resistance based on kdr mutation in V. destructor in apiaries.