El género Argiope (Araneae: Araneidae) en la Provincia de Chiriquí, Panamá

En este estudio se presentan las especies del género Argiope Audouin, 1827 (Araneae: Araneidae), encontradas en áreas agrícolas y urbanas de la Provincia de Chiriquí, Panamá. Para ello, entre los meses de agosto y noviembre de 2020, se visitaron las localidades de David, Alanje, Bugaba, Paso Ancho y Cerro Punta. Se realizaron muestreos aleatorios tanto en cultivos como en vegetación aledaña, en búsqueda de especímenes de Argiope, llevándose además un registro fotográfico y la georreferenciación. Los arácnidos fueron revisados en laboratorio para su identificación, apoyándose con literatura especializada. De acuerdo con los resultados, la especie Argiope argentata (Fabricius, 1775), estuvo presente en las cinco localidades visitadas; mientras que Argiope trifasciata (Forskal, 1775) sólo se ubicó en Paso Ancho, Distrito de Tierras Altas. Si bien el género es referido como cosmopolita y de amplia distribución en América, la predominancia de A. argentata sugiere que la misma podría poseer una mayor capacidad de adaptación que A. trifasciata. En conclusión, se confirman dos especies del género Argiope para la Provincia de Chiriquí.

Scalable Spider Silk Inspired Materials with High Extensibility and Super Toughness

Spiders silks have extraordinary strength and toughness simultaneously, thus has become dreamed materials by scientists and industries. Although there have been tremendous attempts to prepare fibers from genetically manufacture spider silk proteins, however, it has been still a huge challenge because of tedious procedure and high cost. Here, a facile spider-silk-mimicking strategy is reported for preparing highly scratchable polymers and supertough fibers from chemical synthesis route. Polymer films with high extensibility (>1200%) and supertough fibers (~387 MJ m-3) are achieved by introducing polypeptides with β-sheet and α-helical structure in polyureathane/urea polymers. Notabley,the toughness of the fiber is more than twice the reported value of a normal spider dragline silk, and comparable with the toughest spider silk, aciniform silk of Argiope trifasciata.

Phylogeography of the ‘cosmopolitan’ orb-weaver Argiope trifasciata (Araneae: Araneidae)

Few spider species show truly cosmopolitan distributions. Among them is the banded garden spider Argiope trifasciata, which is reported from six continents across major climatic gradients and geographical boundaries. In orb-weaver spiders, such global distributions might be a result of lively dispersal via ballooning. However, wide distributions might also be artefactual, owing to our limited understanding of species taxonomy. To test the hypothesis that A. trifasciata might be a complex of cryptic species with more limited geographical ranges, we investigated the biogeographical structure and evolutionary history of A. trifasciata through a combination of time-calibrated phylogenetic analyses (57 terminals and three genes), ancestral range reconstruction and species delimitation methods. Our results strongly suggest that A. trifasciata as currently defined is not a single species. Its populations fall into five reciprocally monophyletic clades that are genetically distinct and have evolutionary origins in the Plio-Pleistocene. These clades are confined to East Asia, temperate Australia, Hawaii, the New World and the Old World (Africa and most of the Palaearctic). Our results provide the basis for future investigation of morphological and/or ecological disparity between the populations that are likely to represent species, in addition to examinations of the attributes and dispersal modes of these species.

Properties of orb weaving spider glycoprotein glue change during Argiope trifasciata web construction

An orb web’s prey capture thread relies on its glue droplets to retain insects until a spider can subdue them. Each droplet’s viscoelastic glycoprotein adhesive core extends to dissipate the forces of prey struggle as it transfers force to stiffer, support line flagelliform fibers. In large orb webs, switchback capture thread turns are placed at the bottom of the web before a continuous capture spiral progresses from the web’s periphery to its interior. To determine if the properties of capture thread droplets change during web spinning, we characterized droplet and glycoprotein volumes and material properties from the bottom, top, middle, and inner regions of webs. Both droplet and glycoprotein volume decreased during web construction, but there was a progressive increase in the glycoprotein’s Young’s modulus and toughness. Increases in the percentage of droplet aqueous material indicated that these increases in material properties are not due to reduced glycoprotein viscosity resulting from lower droplet hygroscopicity. Instead, they may result from changes in aqueous layer compounds that condition the glycoprotein. A 6-fold difference in glycoprotein toughness and a 70-fold difference in Young’s modulus across a web documents the phenotypic plasticity of this natural adhesive and its potential to inspire new materials.

Towards Spider Glue: Long-read scaffolding for extreme length and repetitious silk family genes AgSp1 and AgSp2 with insights into functional adaptation

The aggregate gland glycoprotein glue coating the prey-capture threads of orb weaving and cobweb weaving spider webs is comprised of silk protein spidroins (spider fibroins) encoded by two members of the silk gene family. It functions to retain prey that make contact with the web, but differs from solid silk fibers as it is a viscoelastic, amorphic, wet adhesive that is responsive to environmental conditions. Most spidroins are extremely large, highly repetitive genes that are impossible to sequence using only short-read technology. We sequenced for the first time the complete genomic Aggregate Spidroin 1 (AgSp1) and Aggregate Spidroin 2 (AgSp2) glue genes of Argiope trifasciata by using error-prone long reads to scaffold for high accuracy short reads. The massive coding sequences are 42,270 bp (AgSp1) and 20,526 bp (AgSp2) in length, the largest silk genes currently described. The majority of the predicted amino acid sequence of AgSp1 consists of two similar but distinct motifs that are repeated ~40 times each, while AgSp2 contains ~48 repetitions of an AgSp1-similar motif, interspersed by regions high in glutamine. Comparisons of AgSp repetitive motifs from orb web and cobweb spiders show regions of strict conservation followed by striking diversification. Glues from these two spider families have evolved contrasting material properties in adhesion, extensibility, and elasticity, which we link to mechanisms established for related silk genes in the same family. Full-length aggregate spidroin sequences from diverse species with differing material characteristics will provide insights for designing tunable bio-inspired adhesives for a variety of unique purposes.