• Journal of Ecology and Environment
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• v.48 no.3
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• pp.207-213
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• 2024

Spiders play a vital role in agricultural ecosystems by capturing and preying on small insects, thereby controlling the pests around crops. However, without directly collecting the specimen, it is challenging to accurately determine the species of the spider that formed the web and its diet. Spiders dissolve their prey with digestive fluids while consuming; thus, leaving very little residue in their digestive system. This study aimed to identify the spider that formed the web and the prey caught in the web using environmental DNA (eDNA) present in the spider web. For this purpose, eDNA using the mitochondrial cytochrome C oxidase subunit I (COI) gene was extracted from five adjacent spider webs collected from residences near agricultural environments. Based on the genes extracted from spider webs, it was confirmed that the most commonly found gene in all five spider webs was COI of Parasteatoda tepidariorum, and no other spider genes were detected. Among the five spider webs, prey was found in only one web, and in that web, genes of arthropods other than spiders were detected. The genes of the prey found in the spider web were identified to be those of Orthocladius tamarutilus, Tanytarsus tamagotoi, and Yemma exilis. Thus, without directly collecting arthropod specimens from the spider web, it was possible to identify the spider and its prey. This provides crucial information that can help in clearly understanding the predatory activities of spiders in agricultural ecosystems in the future.

• Journal of Ecology and Environment
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• v.38 no.2
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• pp.157-162
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• 2015

The physical factors of Argiope bruennichi (Araneae, Araneidae) that influence the stabilimentum decoration on the web, a conspicuous white silk structure reflecting much more ultraviolet light than other spider silks in the web, have been poorly understood. In this study, individual variables involved in decorating the webs with stabilimenta by A. bruennichi were examined. The results revealed that the physical condition of the female A. bruennichi affected the behaviors of the stabilimentum decoration on the web. Among the 82 female spiders building their webs, the 49 female spiders adding upper and lower stabilimenta on their web weighed less, and had a narrower cephalothorax and shorter abdomen than the 33 female spiders that did not use stabilimentum. The heavier females decorated their webs with stabilimentum of greater widths. There were also significant positive relationships between the stabilimentum area and the female spider's cephalothorax width, and between the stabilimentum area and female spider's abdomen length. Taken together, this study suggests that spiders allocate their resources in stabilimentum decoration as a functional response to the spider's physical conditions, and also supports the "prey-attraction hypothesis," which states that the use of stabilimentum increases the foraging success by attracting more prey to the web.

• Animal cells and systems
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• v.3 no.2
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• pp.161-165
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• 1999

Nephila clavata, a golden orb-web spider, was studied at two different field sites with respect to web size, height, and orientation. A majority of spiders at Site 1 (a band of shrub bush) built their webs parallel or nearly parallel to the edge of the bush. Similarly, at Site 2 (near a pond), most webs were aligned with the shoreline of the pond. Among the possible determining factors for the observed patterns of web orientation, wind and light did not appear important. Instead, the movement direction of insect prey appeared largely responsible. Disproportionately more webs faced outside the bush and toward the pond than inside the bush and away from the pond at Site 1 and 2, respectively. Such trend was more apparent for larger spiders with larger webs.

• Animal cells and systems
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• v.3 no.2
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• pp.167-172
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• 1999

We report for the first time the life history of a 'social' spider, Philoponella prominens, living in a temperate region. Philoponella prominens hibernated as immatures or subadults for 7-8 months in 1995 and 1996 from September-October to April-May in central Korea. When they emerged from their winter hibernation, a majority began their lives as commensals in the webs of other species. As the mating season approached, however, commensal spiders switched to become colonial or solitary. The mating season began in early June and lasted until early August. Newly-hatched spiderlings began to appear in the field in late June. They formed a colony by building their webs connected to the mother's by using pan of the mother's web as supporting substrates. As the season progressed, however, some of the colonial spiderlings became commensal or solitary individuals. Our field observations suggest that Philoponella prominens form colonies or commensal associations to reduce the web-building cost.

• Journal of Species Research
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• v.11 no.2
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• pp.94-97
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• 2022

Linyphiidae Blackwall, 1859 is one of the most diverse and largest families within the order Araneae Clerck, 1757. Of the currently 60 valid species of the genus Neriene Blackwall, 1833 worldwide, 10 species are distributed in Korea. The males of the new sheet-web spider Neriene bovista sp. nov. were recently collected with a sweep net between the shrubs of mixed forests from the hilly valley with well conserved nature in Uljin-gun, Gyeongsangbuk-do (the middle east coast region) during a seasonal survey of the spider fauna in hilly terrains in 2017-2018. The present study describes a new sheet-web spider, Neriene bovista sp. nov. with a diagnosis, detailed description, morphological illustrations, and a distribution map from Korea. The new species has a characteristic mushroom-like tip of the terminal apophysis, the truncated tip of anterior projection, and the bifurcated lateral projection of the lamella compared to the congeners of the genus Neriene Blackwall, 1833.

• Applied Microscopy
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• v.51
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• pp.11.1-11.9
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• 2021

Spider capture silk is a natural scaffolding material that outperforms most synthetic materials in terms of its combination of strength and elasticity. Among the various kinds of silk threads, cribellar thread is the most primitive prey-capturing type of spider web material. We analyzed the functional organization of the sieve-like cribellum spigots and specialized calamistral comb bristles for capture thread production by the titanoecid spider Nurscia albofasciata. The outer cribellar surface is covered with thousands of tiny spigots, and the cribellar plate produces non-sticky threads composed of thousands of fine nanofibers. N. albofasciata cribellar spigots are typically about 10 ㎛ long, and each spigot appears as a long individual shaft with a pagoda-like tiered tip. The five distinct segments comprising each spigot is a defining characteristic of this spider. This segmented and flexible structure not only allows for spigots to bend individually and join with adjacent spigots, but it also enables spigots to draw the silk fibrils from their cribella with rows of calamistral leg bristles to form cribellar prey-capture threads.

• Animal cells and systems
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• v.12 no.2
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• pp.109-116
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• 2008

Among the four kinds of silk glands in the funnel-web spider Agelena limbata, the ampullate gland for dragline silk production is the most predominate one in both sexes, and is composed of three functional parts-excretory duct, storage ampulla and convoluted tail regions. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another two pairs of minor ampullate glands supply the middle spinnerets. There are no apparent differences between the major and minor ampullate glands not only the external spigots but also their internal silk glands. However, the microstructure is very unique in this spider, because each gland has spherical shaped storage sac with twig-like branched tails. Nevertheless, the wall of the secretory region is similarly composed of a single layer of epithelial cells. The mature secretory silks in glandular epithelium are closely packed and accumulated as electron-opaque vesicles. Most of the secretory products which originated from the rough endoplasmic reticula(rER) are grown up by fusion with the surrounding small vesicles however, the Golgi complex does not seem to play an important role in this process of secretion.

• Applied Microscopy
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• v.50
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• pp.9.1-9.8
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• 2020

The fine structural characteristics of cardiac muscle cells and its myofibril organization in the orb web spider N. clavata were examined by transmission electron microscopy. Although myofibril striations are not remarkable as those of skeletal muscles, muscle fibers contain multiple myofibrils, abundant mitochondria, extensive sarcoplasmic reticulum and transverse tubules (T-tubules). Myofibrils are divided into distinct sarcomeres defined by Z-lines with average length of 2.0 ㎛, but the distinction between the A-band and the I-bands is not clear due to uniform striations over the length of the sarcomeres. Dyadic junction which consisted of a single T-tubule paired with a terminal cisterna of the sarcoplasmic reticulum is found mainly at the A-I level of sarcomere. Each cell is arranged to form multiple connections with neighboring cells through the intercalated discs. These specialized junctions include three types of intercellular junctions: gap junctions, fascia adherens and desmosomes for heart function. Our transmission electron microscopy (TEM) observations clearly show that spider's cardiac muscle contraction is controlled by neurogenic rather than myogenic mechanism since each cardiac muscle fiber is innervated by a branch of motor neuron through neuromuscular junctions.

• Applied Microscopy
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• v.43 no.2
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• pp.65-74
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• 2013

Although the geometrical difference in body position between web-building and wandering spiders could affect the organization of their central nervous system (CNS), however most of our informations about spider's CNS are dependent on those revealed from the wandering spiders. Therefore, this paper describes microstructural organizations of the CNS in the geometric orb-web spider Araneus ventricosus. Similarly to other wandering spiders, the CNS of A. ventricosus is also consisted of a dorsal supraesophageal ganglion and a ventral subesophageal mass. The supraesophageal ganglia are fused together and made up of a large sized nerve cell clusters, whereas the subesophageal ganglia are made up of the foremost part of the ventral nerve cord. It has been revealed that the only nerve arising from the supraesophageal mass was the optic nerve which connected with four pairs of eyes, whereas a pair of pedipalpal and four pairs of appendage nerves including abdominal nerve pairs were arisen from the subesophageal nerve mass. Fibrous masses are highly organized into longitudinal and transverse tracts, and are only consisted of processes of neurons and the terminal ramnifications of peripheral sensory neurons. In addition, central fibrous mass of both the brain and the subesophageal mass are totally devoid of nerve cell bodies.

• Applied Microscopy
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• v.33 no.4
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• pp.315-323
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• 2003

The fine structural characteristics of the spinnerets and spigots of the silk producing apparatus in the adult funnel-web spider, Agelena limbata, were analysed with the light and scanning electron microscopes. Silk producing apparatus of this spider was composed of three pairs of spinnerets (anterior, median, posterior) and four different types of spigots-ampullates, tubuliforms, pyriforms and aciniforms. By the examination of their ultrastructural characteristics, it has been revealed that each spigot on the spinnerets are connected through the typical silk gland within abdominal cavity. Among the three pairs of spinnerets, the posterior pairs were highly elongated and has most characteristic features. Two pairs of large ampullates were connected to anterior spinneret and another two pairs of small ampullates to median spinnerets. Spigots of the tubuliforms were observed only in female and were connected both of median and posterior spinnerets respectively. While spigots of the pyriforms were connected on the anterior spinnerets but aciniforms on both of median and posterior spinnerets respectively.