20th International Congress of Arachnology

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they are in, and various characteristics of their poten-
tial mate. In the wolf spider, Rabidosa punctulata,
males commonly adopt one of two mating tactics when
encountering a female, multimodal courtship or the
more aggressive direct mount that often incorporates
grappling with females for copulation. While females
of closely related species mate only once and become
unreceptive and aggressive, a recent study showed that
female R. punctulata mates multiply in a short time
period. Here we explored how female mating status
affects male mating behaviors. We exposed males to
females that had or had not mated in previous trial and
observed the mating tactics expressed. Previously mated
females re-mated in 34% of second trials. The mating
status of females affected the mating tactic that males
used. Males paired with already mated females were
significantly more likely to use grappling during the trial
when compared to males that were paired with unmated
females. Grappling was the most successful tactic at
acquiring copulations with already mated females. This
could be due to reduced receptivity by mated females not
approaching males that simply adopt courtship.
Keywords: mating tactics, context dependent, multiple
mating, Lycosidae
Oral presentation
Chemical and mechanical warfare: the
defenses of armored harvestmen against
spiders and flatworms
Rodrigo H Willemart, Marcos Silva, Fernando Carbayo
Escola de Artes Ciências e Humanidades, Universidade
de São Paulo. Rua Arlindo Bettio 1000. 03828-000,
São Paulo, Brazil
Most spectacular adaptations exist in nature when it comes
to predator-prey interactions but few studies report how
the same prey react against different predators. Here we
summarize studies we have been carrying out in the last
five years on how Neotropical armored harvestmen defend
themselves against sympatric and also nocturnal spiders
and flatworms. We used two harvestmen species, one spit-
ting spider, two large ctenids, one recluse spider and one
flatworm. We paired predator and prey, described their
behaviors and tested hypotheses on the role of chemical
defenses and the survival value of the thick harvestmen
cuticle. Against spiders, the armor proved to be an excel-
lent defense except against recluse spiders. These spiders
have a remarkable strategy that involves searching for the
soft parts like leg articulations and the distal parts of the
legs and were able to kill harvestmen in most cases. The
armor was also useless against flatworms, which hamper
prey’s movement with mucus, kill and ingest the internal
organs of harvestmen. Against spiders, harvestmen seldom
used their defensive secretions but these proved to effi-
ciently repel flatworms. Against both predators, pinching
with spines on legs IV repelled the predator, in some cases
almost cutting the flatworm body in two pieces. While the
classical literature emphasized the importance of chemical
defense for harvestmen, we are showing that the relative
importance of each defense is predator dependent.
Keywords: animal behavior, predator-prey interaction,
defensive behavior
Student - oral presentation
Investigating the influence and regulation
of catecholamines on circadian rhyth-
micity of anti-predator behavior in the
orb-weaving spiders
*Rebecca J. Wilson, Jennifer B. Price, Thomas C. Jones
Department of Biological Sciences, East Tennessee State
University, PO Box 70300 Johnson City, TN 37614, USA
While it is widely assumed that circadian rhythms benefit
organisms by allowing them to anticipate changing
conditions, only a few studies have directly tested this.
Being both predator and prey, orb-weaving spiders offer
a novel, tractable model system to test whether circadian
rhythms are adaptive due to their variety of temporal
foraging strategies across species. Previous work sug-
gests that spiders modulate their aggression/wariness
over the 24-cycle and that aggression and wariness are
modulated by biogenic amines (neurohormones). In this
study, we analyzed temporal changes in catecholamine
levels and transcriptional regulation in the orb-weaving
200 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing