20th International Congress of Arachnology

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DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
20th International Congress of Arachnology
Student - oral presentation
Sexual behavior and mating plugs as a
tool of mating choice in the Colombian
orb-web spider Leucauge acuminata
(Araneae, Tetragnathidae)
*Linda Hernández Duran1, Jorge Molina1 , Anita
Aisenberg2
1Centro de Investigaciones en Microbiología y Para-
sitología tropical–CIMPAT. Universidad de los Andes,
Bogotá, Colombia; 2Laboratorio de Etología, Ecología
y Evolución, Instituto de Investigaciones Biológicas
Clemente Estable, Uruguay
Females of some species of spiders can bias male
paternity through different mating strategies such as
rejecting a mating, flushing out the sperm or selecting
the sperm of one male over the other. In Leucauge
orb web spiders, females produce a copulatory plug
during or after mating that could be a useful tool to
bias paternity. Leucauge acuminata is a very fre-
quent spider in Cundinamarca, Colombia; however,
the sexual behavior of this species is completely
unknown. Our aim was to describe courtship and
mating behavior of L. acuminata, record plug forma-
tion and test its correlation with male sexual behavior.
We recorded individually the courtship and copulation
of 20 virgin females. In 11 cases, the copulatory plug
was present, even though all females mated. Male
courtship behaviors during mating such as tapping
the female—touching synchronically the female
with forelegs (z=2.048; p=0.04), palpal insertions
(z=2.232; p=0.02) and mating duration (z=2.465;
p=0.0137) were positively related with plug formation.
We observed six female cannibalism attempts during
mating, which could be related to female choice based
on male copulatory performance. We will discuss and
compare our results with data available for other
species of the genus and the cryptic female choice
hypotheses.
Keywords: copulatory plugs, Leucauge acuminata,
cryptic female choice, male performance.
Student - poster presentation
Effects of Wolbachiainfection on aggression
in a socially polymorphic spider, Anelosi-
mus studiosus(Araneae: Theridiidae)
*Ashley Herrig, Thomas C. Jones
Department of Biological Sciences, D.M. Brown Hall,
PO Box 70703, East Tennessee State University, USA
The endosymbiont bacterium Wolbachia is well known for a
variety of effects it can have on its host through cellular and
reproductive processes, such as cytoplasmic incompatibility,
parthenogenesis, feminization and male killing. It has also
recently come to light that Wolbachia can have effects on
the nervous system as well, including effects on olfaction
and the mediation of octopamine levels. This project aims
to investigate a potential proximate cause of social behavior
in the socially polymorphic spider, Anelosimus studiosus.
While most A. studiosus express an aggressive phenotype
and tend to live in solitary colonies, a rarer docile pheno-
type is much more tolerant of conspecifics and is often
found in multi-female colonies characterized by cooperative
brood care and foraging. Recent work has shown that lower
levels of octopamine in the docile phenotype are related
this social behavior, but the proximate causes of lower
octopamine levels remain poorly understood. In this study
we investigate a potential causal link between lower levels
of aggression in A. studiosus and Wolbachia infection. In
Drosophila, Wolbachia infection have been linked to lower
levels of octopamine and a corresponding decrease in
aggression. Moreover, Wolbachia may be inherited through
ingestion when hosts are in larval or early developmental
states. Juveniles of docile A. studiosus can be fed by multiple
females via regurgitation during development, which could
a potential vector for horizontal transmission of Wolbachia
infection. We will present results of quantitative genetic
screening of aggressive and docile females for Wolbachia
infection. Research which focuses on the effects of endog-
enous microorganisms on social behavior is novel and our
results could potentially transform current understandings
of key mechanisms in biogenic amine production.
Keywords: social behavior, endosymbionts, biogenic
amines, Wolbachia