Germán H. Cheli

Efficient sampling of ground-dwelling arthropods using pitfall traps in arid steppes

Pitfall trapping is probably the most frequently used method for sampling ground-dwelling arthropods. While the capture of specimens in pitfall traps largely depends on the number of individuals in the sampled area, trap design and trapping effort for a given environment, can also affect sampling success. The aim of this study was to determine the best pitfall trapping design for collecting ground-dwelling arthropods in the wind-blown and cold arid steppe areas of Patagonia. We tested four designs of traps, six types of preservative and different times of activation as well as the quantity of traps. Both preservation attributes and sampling efficiency differed between different trap designs and fluids compared. We conclude that in order to obtain reliable data on the structure of a community of ground-dwelling arthropods in Patagonia, at least three pitfall traps per experimental unit are required. In addition, traps should be opened for a minimum of 10 days filled with 300 ml of 30% ethylene glycol. We also suggested the use of a simple trap design (i. e. without funnel or roof). We believe these findings will contribute to more appropriate sampling of the ground dwelling fauna of Patagonia as well as other arid areas, leading to more reliable diversity studies.

The ground-dwelling arthropod community of Península Valdés in Patagonia, Argentina

Abstract This is the first study based on a planned and intensive sampling effort that describes the community composition and structure of the ground-dwelling arthropod assemblage of Península Valdés (Patagonia). It was carried out using pitfall traps, opened for two weeks during the summers of 2005, 2006 and 2007. A total of 28, 111 individuals were caught. Ants (Hymenoptera: Formicidae) dominated this community, followed by beetles (Coleoptera) and spiders (Araneae). The most abundant species were Pheidole bergi Mayr (Hymenoptera: Formicidae) and Blapstinus punctulatus Solier (Coleoptera: Tenebrionidae). Two new species were very recently described as new based on specimens collected during this study: Valdesiana curiosa Carpintero, Dellapé & Cheli (Hemiptera, Miridae) and Anomaloptera patagonica Dellapé & Cheli (Hemiptera, Oxycarenidae). The order Coleoptera was the most diverse taxa. The distribution of abundance data was best described by the logarithmic series model both at the family and species levels, suggesting that ecological relationships in this community could be controlled by a few factors. The community was dominated by predators from a trophic perspective. This suggests that predation acts as an important factor driving the distribution and abundances of surface-dwelling arthropods in this habitat and as such serves as a key element in understanding desert, above-ground community structure. These findings may also be useful for management and conservation purposes in arid Patagonia.

Leaf traits, water stress, and insect herbivory: Is food selection a hierarchical process?

Abstract Plant water stress can affect selectivity by insect herbivores. Numerous studies have shown greater insect preference for water-stressed plants, but others have reported the opposite response. We evaluated leaf consumption by adults of Nyctelia circumundata (a chewing insect) in leaves of Larrea divaricata and Prosopis alpataco. Three bioassays (two-way choice tests) were performed: two intra-specific comparisons between well-watered (+W) and water-stressed (−W) leaves of each species and one inter-specific comparison between leaves of the two species. Leaf biomass was reduced by water stress in both species. Nitrogen concentration in leaves (N) was reduced by drought in P. alpataco. In contrast, total phenolics and specific leaf area (SLA) did not differ between treatments within species. Nyctelia circumundata did not show preference by any water supply regimes in intra-specific comparisons. In contrast, in inter-specific choice tests, it showed a marked preference for P. alpataco, which is the species with the highest nitrogen concentration and lowest total phenolics concentration. In intra-specific comparisons, maximum leaf consumption was inversely related to SLA in both species. Furthermore, in P. alpataco, N concentration was positively related to maximum leaf consumption and negatively related to leaf water content (LWC). In contrast, in inter-specific comparisons, total phenolics was negatively related to maximum leaf consumption, while N concentration exhibited the opposite trend. These results suggest that food selection is a hierarchical process where chemical attributes (i.e., total phenolics and N) are taken into account for species selection, and physical attributes (i.e., SLA and LWC) for choosing individuals inside species.

Disentangling the Effect of Climate and Human Influence on Distribution Patterns of the Darkling Beetle Scotobius pilularius Germar, 1823 (Coleoptera: Tenebrionidae)

Abstract. Scotobius pilularius Germar 1823 (Tenebrioninae: Scotobiini) is mainly distributed in natural temperate and mesic grasslands of the Pampean biogeographic province. However, it is also found in climatically extreme environments such as cold and dry grasslands within the Patagonian biogeographic province. In these extreme environments, S. pilularius is found outside of natural habitats, in areas associated with human settlements. In the present paper, the role of climatic conditions and human settlements as determinants of the observed spatial distribution of S. pilularius in its natural distribution and outside that area is assessed. Three following hypotheses are tested: species occurrence is determined by i) climate; or ii) human settlements; or iii) both climate and human settlements. The results suggest that, while the climate and human settlements hypothesis is consistent with the data acquired within the S. pilularius natural distribution area, only the human influence hypothesis significantly explains its distribution outside of its natural area. This outcome suggests that S. pilularius moved from living in a complete disassociation to human settlements or asynanthropy before human settlements in its natural area, to living in close association with human settlements or synanthropy outside of its natural area.

Animal Diversity, Distribution and Conservation

In this chapter, we summarize the ecological information available on the species of arthropods, reptiles, terrestrial birds and mammals known to occur at Peninsula Valdes, within the context of the Monte and Patagonia eco-regions. Two hundred species of insects and spiders, 12 species of reptiles, 139 species of birds and 23 species of native mammals inhabit today the island-like peninsula. We describe the community structure, distribution and abundance of the different taxa according to current knowledge. As the Peninsula Valdes region is a World Natural Heritage Site and a provincial protected area of high importance for the conservation of biodiversity and the regional economy, we found relevant to summarize knowledge on the effects of human activities on different components of biodiversity. Habitat degradation, grazing by domestic sheep and poaching are major threats to wildlife, although Peninsula Valdes still harbours some of the most abundant populations of wild species in Patagonia. It is a priority to implement the management plan available for Peninsula Valdes, taking into account the interactions between biodiversity, the different human activities and the physical environment. At the same time, it is necessary to identify and implement actions to conserve wild species and habitats, and also to develop programmes for the coexistence of responsible human activities and healthy wildlife populations.

Two new species of Nyctelia Latreille (Coleoptera: Tenebrionidae) from Argentinean Patagonia with zoogeographical and ecological remarks

Two new species of the genus Nyctelia Latreille (Pimeliinae: Nycteliini) from Argentinean Patagonia, N. sulcogranata sp. nov. and N. recteplicata sp. nov., are described. Distributional maps, habitus, photographs and illustrations of genitalic features for these two new species are included, with comparisons to other known species of the genus. A discussion is presented on distributional habitat records and biogeography.

A Tenebrionid beetle’s dataset (Coleoptera, Tenebrionidae) from Peninsula Valdés (Chubut, Argentina)

Abstract The Natural Protected Area Peninsula Valdés, located in Northeastern Patagonia, is one of the largest conservation units of arid lands in Argentina. Although this area has been in the UNESCO World Heritage List since 1999, it has been continually exposed to sheep grazing and cattle farming for more than a century which have had a negative impact on the local environment. Our aim is to describe the first dataset of tenebrionid beetle species living in Peninsula Valdés and their relationship to sheep grazing. The dataset contains 118 records on 11 species and 198 adult individuals collected. Beetles were collected using pitfall traps in the two major environmental units of Peninsula Valdés, taking into account grazing intensities over a three year time frame from 2005–2007. The Data quality was enhanced following the best practices suggested in the literature during the digitalization and geo-referencing processes. Moreover, identification of specimens and current accurate spelling of scientific names were reviewed. Finally, post-validation processes using DarwinTest software were applied. Specimens have been deposited at Entomological Collection of the Centro Nacional Patagónico (CENPAT-CONICET). The dataset is part of the database of this collection and has been published on the internet through GBIF Integrated Publishing Toolkit (IPT) (http://data.gbif.org/datasets/resource/14669/). Furthermore, it is the first dataset for tenebrionid beetles of arid Patagonia available in GBIF database, and it is the first one based on a previously designed and standardized sampling to assess the interaction between these beetles and grazing in the area. The main purposes of this dataset are to ensure accessibility to data associated with Tenebrionidae specimens from Peninsula Valdés (Chubut, Argentina), also to contribute to GBIF with primary data about Patagonian tenebrionids and finally, to promote the Entomological Collection of Centro Nacional Patagónico (CENPAT-CONICET) and its associated biodiversity data. For these reasons, we believe that this information will certainly be useful for future faunistic, ecological, conservational and biogeographical studies.

The Patagonian Steppe biogeographic province: Andean region or South American transition zone?

America comprises three biogeographic regions: Nearctic, Neotropical and Andean. In between them, two transition zones (TZ) have been proposed: Mexican and South American. The biogeographic provinces belonging to a TZ have no predominance of biotic elements pertaining to each of its bordering regions. Regarding the Andean region, one of its provinces, the Patagonian Steppe, presents a mixture of different biogeographic elements, which are typical of transition zones. Because of this, we assessed whether the Patagonian Steppe belongs to the Andean region or whether it forms the southernmost part of the South American TZ. We gathered phylogenetic information from 177 taxa that inhabit the Patagonian Steppe and established to which biogeographic element they belong. We followed the criterion that an area can be considered as part of a region when at least 70% of its biota has the same origin, that is belongs to the same biogeographic element. In contrast, when the biota of an area presents a similar percentage of its different biogeographic elements, it could be considered as belonging to a transition zone. We found that the Patagonian Steppe presents a similar proportion of genera of Andean as well as neotropical origin. Therefore, we propose that this province should be included in the South American transition zone. Moreover, inclusion of the Patagonian Steppe as part of this TZ will make it the largest TZ of America, encompassing most of the arid lands of South America.

Structure of ground-dwelling arthropod assemblages in vegetation units of Área Natural Protegida Península Valdés, Patagonia, Argentina

Knowing the spatial variation of insect and arachnid assemblages and their relationship with habitat variables is critical to understand the structure and dynamics of these communities in arid environments. The aim of this paper was to analyze the variation in ground-dwelling arthropod assemblages across three representative vegetation units of the Área Natural Protegida Península Valdés (Patagonia, Argentina). We asked whether environmental differences among representative vegetation units were associated to distinct arthropod assemblages. We selected three plant communities: grass, dwarf-shrub, and shrub steppes, and established three sampling sites within each of them. We measured variables of vegetation structure and soil characteristics and collected the arthropods using 10 pitfall traps per site. We analyzed the structure of arthropod assemblages at both family and ant species taxonomic levels. Each plant community displayed a distinctive assemblage, with differences in diversity, taxa abundance, trophic structure and functional groups of ants. Vegetation variables explained a higher proportion of the variation in the structure of the ground-dwelling arthropod assemblages than the soil variables. This work highlights the importance of the different vegetation units for the conservation of ground-dwelling arthropod biodiversity in Península Valdés.

Fourth International Tenebrionoidea Symposium

The Fourth International Tenebrionoidea Symposium (ITS) was hosted by the Instituto Argentino de Investigaciones de las Zonas Áridas (IADIZA) and the Centro Científico Tecnológico (CCT-CONICET Mendoza) in Mendoza, Argentina on November 25th and 26th, 2015. Researchers from nine countries participated with a total of 31 attendees (Fig. 1). The history of the three first formal international meetings on Tenebrionoidea can be found in the editorial of the Third International Tenebrionid Symposium (Smith et al. 2014). After the Third International Tenebrionid Symposium in Arizona USA, voting was carried out to decide the host city for the next meeting. After over a month of voting, Mendoza, Argentina was chosen to host that meeting. A steering committee was assembled with representatives from Centro Científico Tecnológico (CCT-CONICET) Mendoza, Centro Nacional Patagónico (CENPAT CONICET) Puerto Madryn, Chubut, and the Universidad de Buenos Aires with the objectives of continuing this successful tradition and encouraging tenebrionoid workers from around the world to meet and share their research. Presentations were given on November 25th and 26th, 2015. During the meeting eighteen 20-minute talks and ten posters were given (see http://wiki.mendozaconicet.gob.ar/images/5/5e/ProgrameMendoza symposium.pdf) ranging, as in previous meetings, from species-level revisions to broad scale Tenebrionidae phylogenies, biogeography, and faunistic inventories. In addition, presentations on research using tenebrionid beetles in innovative ways were presented, including: species of Tenebrionidae associated with decaying carcasses, potential adverse effects of volcanic ash on tenebrionid larvae, a fossil darkling beetles assemblage, the effect of climate and human influence on distribution patterns of species of Tenebrionidae, and ecological remarks on epigean tenebrionids and their relationship with anthropic desertification. Presentations were also given on two families beyond Tenebrionidae: Zopheridae and Meloidae (Tenebrionoidea). For the first time, a translator (Dr. Florencia Fernández Campón, English-Spanish) was also available to help facilitate communication among participants. The presentations were received with interest and stimulated thoughtful discussions throughout the meeting. The Sociedad Entomológica Argentina (who also sponsored the meeting) offered several books for sale during the meeting: “Biodiversity of Argentinean Ar thro pods” vol. 2, 3, and 4, and “Catalog of phyto phag ous insects of Argentina and its associated plants”. Group discussions also took place during the symposium on potential large scale tenebrionid projects, the organization of a Proceedings volume from the Symposium, collecting localities and travel-related activities for the post-meeting trip, and potential localities for the Fifth International Tenebrionoidea Symposium. FOURTH INTERNATIONAL TENEBRIONOIDEA SYMPOSIUM