The 26th European Congress of Arachnology [Preface]

The 26th European Congress of Arachnology (4-8 September 2011) was held for the first time in Israel, and for the first time outside the European continent. The meeting was hosted by the Blaustein Institutes for Desert Research, at the Sede Boqer Campus of Ben-Gurion University of the Negev

Ground spider communities in experimentally disturbed Mediterranean woodland habitats

The protected Mediterranean woodland habitats in Israel are undergoing tree encroachment, resulting in loss of open patches with herbaceous vegetation. We suggested that this process results in a ground spider community dominated by shade-loving species. At three Mediterranean woodland sites located along a rainfall gradient, we examined the effects on the ground-spider community of experimental removal of the woody vegetation in 1000 m2 plots by cutting and overall plant biomass reduction by grazing and browsing by livestock. Pitfall traps were placed in replicated plots of four treatments (control, cutting, grazing/browsing, and cutting together with grazing/browsing) and in two different habitat patch types (open, woody). ANOVA and multivariate analyses were performed on family abundance by treatment and habitat patch type. Tree-cutting reduced the number of families in plots at two of the three sites. Grazing did not have a significant effect on the number of families or on the ground spider community composition. The spider community of cut-woody patches was more similar to that of open patches than to that of uncut woody patches. Most spider families separated along an axis of open versus woody patches, with woody habitat families predominating at all sites. Families typical of open habitats were positively associated with cut-woody patches as well. The overall effect on ground spider diversity of such manipulations may depend on the scale of habitat changes

Technologies bringing young Zebrafish from a niche field to the limelight

Fundamental life science and pharmaceutical research are continually striving to provide physiologically relevant context for their biological studies. Zebrafish present an opportunity for high-content screening (HCS) to bring a true in vivo model system to screening studies. Zebrafish embryos and young larvae are an economical, human-relevant model organism that are amenable to both genetic engineering and modification, and direct inspection via microscopy. The use of these organisms entails unique challenges that new technologies are overcoming, including artificial intelligence (AI). In this perspective article, we describe the state-of-the-art in terms of automated sample handling, imaging, and data analysis with zebrafish during early developmental stages. We highlight advances in orienting the embryos, including the use of robots, microfluidics, and creative multi-well plate solutions. Analyzing the micrographs in a fast, reliable fashion that maintains the anatomical context of the fluorescently labeled cells is a crucial step. Existing software solutions range from AI-driven commercial solutions to bespoke analysis algorithms. Deep learning appears to be a critical tool that researchers are only beginning to apply, but already facilitates many automated steps in the experimental workflow. Currently, such work has permitted the cellular quantification of multiple cell types in vivo, including stem cell responses to stress and drugs, neuronal myelination and macrophage behavior during inflammation and infection. We evaluate pro and cons of proprietary versus open-source methodologies for combining technologies into fully automated workflows of zebrafish studies. Zebrafish are poised to charge into HCS with ever-greater presence, bringing a new level of physiological context

Exploring the Interplay Between Local and Regional Drivers of Distribution of a Subterranean Organism

Caves are excellent model systems to study the effects of abiotic factors on species distributions due to their selective conditions. Different ecological factors have been shown to affect species distribution depending on the scale of analysis, whether regional or local. The interplay between local and regional factors in explaining the spatial distribution of cave-dwelling organisms is poorly understood. Using the troglophilic subterranean spider Artema nephilit (Araneae: Pholcidae) as a model organism, we investigated whether similar environmental predictors drive the species distribution at these two spatial scales. At the local scale, we monitored the abundance of the spiders and measured relevant environmental features in 33 caves along the Jordan Rift Valley. We then extended the analysis to a regional scale, investigating the drivers of the distribution using species distribution models. We found that similar ecological factors determined the distribution at both local and regional scales for A. nephilit. At a local scale, the species was found to preferentially occupy the outermost, illuminated, and warmer sectors of caves. Similarly, mean annual temperature, annual temperature range, and solar radiation were the most important drivers of its regional distribution. By investigating these two spatial scales simultaneously, we showed that it was possible to achieve an in-depth understanding of the environmental conditions that governs subterranean species distribution.Peer reviewe

Seed Predation on Oil-Polluted and Unpolluted Vachellia (Acacia) Trees in a Hyper-Arid Desert Ecosystem

Acacia trees are keystone species in many arid environments, supporting high levels of plant and animal diversity. In Israel, the populations of Vachellia (formerly Acacia) tortilis (Forssk.) and V. raddiana (Savi) are declining at an alarming rate. Severe infestations by bruchid beetles (Coleoptera, Chrysomelidae) are among the major causes of seed mortality, but additional environmental stressors can reduce the defence level of the seeds, exacerbating their susceptibility to predators. In a hyper-arid desert ecosystem affected by two major oil spills (in 1975 and 2014), we quantified seed predation rates caused by insect granivores before and after the pods dropped to the ground. We recorded predation rates of up to 84% for both tree species, and higher predation rates at the ground level than in the canopy, suggesting that repeated infestations occur. These results reinforce the call to protect the populations of large ungulates such as gazelles, which kill the bruchids by feeding upon the pods, and promote seed germination and dispersion. We found no clear evidence of a negative effect of the oil spill on seed predation, indicating that oil pollution did not increase the vulnerability of the seeds to granivores even in trees affected by the recent oil spill.Jacob Blaustein Center for Scientific Cooperationinfo:eu-repo/semantics/publishedVersio

Trunk Refugia : A Simple, Inexpensive Method for Sampling Tree Trunk Arthropods

Trees host a large share of the global arthropod diversity. Several methodologies have been described to sample arthropods from trees, ranging from active sampling techniques (e.g., visual searching, beating, or shaking the branches) to passive sampling devices. The majority of these collection techniques are destructive, and do not specifically target the tree trunk arthropod fauna. Here, we describe an alternative sampling method called trunk refugia (TR). TR are cylindrical shelters made of corrugated cardboard that can be secured to trees using string, and can remain exposed for varying time periods. These refugia are inexpensive, easy to use, and suitable to monitor a diverse array of insects and arachnids. Moreover, TR are nonlethal sampling tools, and allow collecting live individuals for behavioral studies or for rearing.RESUMEN: Los árboles albergan una gran parte de la diversidad global de artrópodos. Varias metodologías han sido descritas para muestrear artrópodos de árboles, desde técnicas activas (e.g., búsqueda visual, red de golpeo) hasta dispositivos de muestreo pasivo. La mayoría de estas técnicas son letales, y no están dirigidas específicamente a los artrópodos de troncos de árboles. Describimos aquí un método alternativo llamado trampas refugio (TR). Las TR son refugios hechos de cartón corrugado que se colocan en los troncos usando cuerda, y pueden permanecer expuestos por períodos variables. Estas trampas son económicas, fáciles de usar, y apropiadas para monitorear una gran variedad de insectos y arácnidos. Además, las TR son no-letales, por lo que permiten la colección de individuos vivos para estudios de comportamiento o crianza.Jacob Blaustein Center for Scientific Cooperation; Israel Nature and Parks Authorities (INPA); Israel's National Nature Assessment Program (HAMAARAG); Israel Ministry of Agriculture (131-1793-14)info:eu-repo/semantics/publishedVersio

Effects of Natural Habitat and Season on Cursorial Spider Assemblages in Mediterranean Vineyards

ABSTRACT: Spiders are potential natural enemies of insect pests in many crops, and their species composition in the crop may be influenced by nearby natural habitats. Here, we examined the effects of the habitat type (different sampling positions within the vineyard and in the nearby natural habitat) on spider assemblages in vineyards. Spider species richness, assemblage composition, and diversity were evaluated by means of pitfall traps in early and late summer, in three commercial vineyards and their adjacent natural habitats in a Mediterranean landscape in northern Israel. We collected 688 spiders, belonging to 25 families and 61 species and morphospecies. Spider richness differed in the two seasons; more species were documented in early summer (47) than in late summer (33). The natural habitat had the highest species richness, with 34 species, while three vineyard positions were inhabited by only 27–31 species each. The natural habitat assemblage differed from the vineyard assemblages, with 15 species that were found only in the natural habitat, yet 11 species were shared by both the natural habitat and all vineyard positions. Both season (early vs. late in the cropping season) and the habitat (vineyard vs. natural) affected the spider assemblage composition. The study documents the large diversity of spiders in a Mediterranean vineyard agroecosystem. The information that we provide here is critical in assessing the potential for conservation biocontrol, where natural habitats may be a source of natural enemies for nearby vineyards.info:eu-repo/semantics/publishedVersio

The global spread of misinformation on spiders

Non peer reviewe