20th International Congress of Arachnology

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88 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing
Student - Oral presentation
Decoration-building behavior in an orb-
weaving spider, Cyclosa octotuberculata
Wenjin Gan1 , Daiqin Li2
1College of Plant Sciences & Technology of Huazhong
Agricultural University, Wuhan, 430070, China;
2Department of Biological Sciences, National University
of Singapore, 117543, Singapore
Many orb-weaving spiders add silk bands, silk tufts, egg
sacs, prey remains or plant detritus so called ‘web decora-
tions’ to their webs. Much attention has been paid to the
functional significance of decorations and to silk decora-
tions built mostly by a single genus, Argiope. By contrast,
few studies have been conducted to investigate other types
of web decorations spun by other groups of orb-weaving
spiders and the materials and behavior used for decorating
webs. Here, using Cyclosa octotuberculata, an orb-weaving
spider that often decorates its web with prey remains, plant
detritus or egg sacs called detritus decorations, as a model
system, we investigated what cues Cyclosa spiders use to
choose decoration materials with different color, texture,
odor, size or weight. We also examined perception of differ-
ent decoration materials (different colors, texture and size
or weights) in eyes of predators. We found that the cues
used by Cylcosa for choosing decorating materials were
their capability and limits of webs other than visual cues,
sensation experienced through touch and odor when vision
is limited. Results also showed that predators preferred
webs decorated with white and mix color detritus to webs
decorated by the other detritus made up of different colors.
We concluded that materials chosen by Cyclosa spiders to
decorate their webs may attract or deter predators.
Keywords: web decorations, detritus, spider, Cyclosa
octotuberculata, orb web
Student - oral presentation
Ultrastructure of chemosensory sensilla in
Argiope bruennichi (Araneae, Araneidae)
*Anne-Sarah Ganske, Carsten H.G. Müller, Gabriele Uhl
University of Greifswald, Zoological Institute and
Museum, Department of General and Systematic
Zoology, Anklamerstr. 20, 17489 Greifswald, Germany
Chemical communication through volatile or contact
pheromones is an important means of spiders, e.g., to
attract and find mating partners and to assess their
reproductive status. Assumed receptors for olfaction are
s-shaped and blunt tipped sensilla with characteristi-
cally striated surfaces and terminal pores. As yet, only
one electrophysiological analysis demonstrated that
these sensilla perceive contact pheromones. The percep-
tion of volatile pheromones has not been tested yet and
it remains to be analyzed if sensilla on different body
parts differ in structure and function. To this aim we
mapped the distribution of the chemosensory sensilla
on legs and pedipalps of Argiope bruennichi males
and females. It is known that male A. bruennichi are
attracted by a volatile sex pheromone only emitted by
virgin females. We explored the fine structure of tip-
pore sensilla on tarsi of legs of A. bruennichi males
by means of Transmission Electron Microscopy. Our
results show that the sensilla possess a thick hair shaft
and a double-lumen divided in three canals. More than
ten dendrites are surrounded by a dendritic sheath.
The cuticular hair shaft shows breakthroughs on the
innermost cuticular sheath which may indicate that
molecules can be transported from the outside to the
innermost canal and not only through the tip-pore. The
next step is to compare ultrastructural traits of these
sensilla from different body regions.
Keywords: chemical communication, TEM, ultrastructure,
tip-pore sensilla, Araneidae
Student - Poster presentation
Structure and distribution of different
sensilla types in Argiope bruennichi
(Araneae, Araneidae)
Anne-Sarah Ganske, Gabriele Uhl
University of Greifswald Zoological Institute and
Museum Department of General and Systematic
Zoology, Anklamerstr. 20, 17489 Greifswald, Germany