• 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 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.

• Journal of Life Science
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• v.21 no.7
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• pp.1009-1015
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• 2011

Web structure of spiders is a foraging strategy as well as an investment to get prey. In order to increase the fitness consequence, spiders change their foraging strategy based on sensory information provided by prey species. We conducted an experiment to demonstrate whether an orb-web building spider, Argiope bruennichi modifies its web-building behavior after experiencing sensory information emitted by a UV recognizing flying insect, Bombus terrestris. To know how the web structure would be modified, we observed web characteristics after providing sensory information of a potential prey species, the bumblebee (experimental group) and compared them to the control group (no information provided). We hypothesized that the spiders of the experimental group would increase investments in their web construction and stabilimentum decoration. The results rejected our hypothesis. Web and stabilimentum constructions decreased in the course of the experiment in both the control group and the experimental group. The individuals did not increase their stabilimentum length and did not extend their web areas, in spite of sensory information given by the nectar collector.

• 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.

• Journal of Wetlands Research
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• v.13 no.1
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• pp.139-148
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• 2011

Web structure of spiders is a foraging strategy as well as an investment to get prey. In order to make a good foraging decision spiders should change its foraging strategy in the basis of sensory information provided by potential prey species. We conducted experiments to demonstrate whether a wasp spider, Argiope bruennichi modifies its web-building behavior after experiencing sensory information emitted by a cricket species, Teleogryllus emma. To know how the web structures would be modified, we quantified web characteristics after providing sensory information of the cricket and compared to the control group. Web construction decreased in the course of the experiment in both, control group(without stimulus) and experimental group(with stimuli). The results did not show remarkable differences between two groups. However, on the first day after providing sensory information of the cricket, the web-building behavior of A. bruennichi decreased only in 3.7% of the experimental group individuals against 11.8% of the control group individuals. The number of the stabilimentum constructions decreased overall in both groups. On the first day the decreasing proportion was doubled in the control group(14.7%), comparing to the experimental group(7.4%). The individuals did not lower its web height and did not extend its web area according to sensory information of the prey.

• Journal of Wetlands Research
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• v.12 no.1
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• pp.41-49
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• 2010

Web building of the spider is an investment behavior for prey foraging with genetic constraint. Individual's decision-making on the web construction depends on diverse environmental variables. This study investigated web structure of the wasp spider, Argiope bruennichi, to compare individual's behaviors in dry field and in wet field. We measured 35 web structures in dry field (Chunma-San, Incheon) showing relatively low humidity (46.4%) and luxuriant herbage, and 13 web structures in the wet rice field (73.9%; Taean-Gun, Chungnam). Comparing to the wet field the individuals in the dry field invested significantly more silk: $32.5{\pm}12.8$ number of silk spirals used in the dry field vs. $16.9{\pm}5.4$ in the wet field. The web area of the dry field was greater than that of the wet field: $976{\pm}643cm^2$ vs. $532{\pm}254cm^2$. The web height, distance between the ground and the center of the web, appeared higher in the dry field than in the wet field: $71.4{\pm}39.6cm$ vs. $49.6{\pm}31.2cm$. Also the web constructed in the dry field showed longer stabilimentum than the web of the wet field: $18.8{\pm}3.4cm$ vs. $3.9{\pm}3.2cm$. The perpendicular inclination and the inclination to East-West of the web showed no difference between the two fields. This study suggests that adult females of A. bruennichi could modulate its construction behavior depending on the micro-habitat factors.

• Journal of Ecology and Environment
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• v.32 no.1
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• pp.19-25
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• 2009

An arthropod community in a rice ecosystem was surveyed to determine the impact of two insecticides frequently used in Korean rice ecosystems: carbofuran 3GR, which targets the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) in the early season and fenobucarb EC, which targets the brown planthopper, Nilaparvata lugens ($St{\aa}l$) (Hemiptera: Delphacidae) in the mid- and late seasons, respectively. Overall, the application of the insecticides reduced density of total arthropods by 48.4% compared to the untreated field, but their impact on each functional group were different. Carbofuran GR treatment on 1 June reduced the L. oryzophilus population significantly until mid-season. The population of filterfeeding chironomids was also reduced by 50%, whereas the spider population was less disturbed. Fenobucarb EC treatment on 16 August significantly reduced N. lugens and detrivorous entomobryid populations until the late season. Both web-building and wandering spiders were also significantly disturbed by fenobucarb EC although the impact differed according to their behavioral differences. While the population of web-building spiders significantly decreased over time, that of wandering spiders recovered from the disturbance a few weeks later.