20th International Congress of Arachnology

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crop, we performed a laboratory experiment exposing
an important pest species to two spider predator species
at different temperatures. First, we assessed the thermal
tolerance (critical thermal maxima or CTM) of the
cucumber beetle (Diabrotica undecimpunctata) pest,
wolf spider (Hogna helluo) predator, and nursery web
spider (Pisaurina mira) predator. Cucumber beetles and
wolf spiders were equally heat tolerant (CTM > 40 C), but
nursery web spiders had relatively limited heat tolerance
(CTM = 34 C). Inside mesocosms, three beetles fed on
squash plants for seven hours alone or in the presence of
a single spider predator of either species at ambient (22 C)
or warmed (38 C) temperature. Beetle feeding increased
with temperature, and while wolf spiders were always
effective predators, nursery web spiders were relatively less
lethal at high temperature. Compared to the non-predator
control, neither spider species reduced herbivory at
ambient temperature. However, at warm temperature both
species of spiders reduced herbivory with evidence of a
dominant non-consumptive effect. Our experiments high-
light the contingent nature of predator-prey interactions
and suggest that non-consumptive effects should not be
ignored when assessing the impact of temperature change.
Keywords: predator-prey interactions, temperature
stress, cucumber beetle
Student - poster presentation
Non-consumptive effects of a spider
predator on plant penetration behavior of
virus vector leafhoppers
Orsolya Beleznai1, Gergely Tholt1 , Botond Pertics2,
Ferenc Samu1
1Zoology Department, Plant Protection Institute, Centre
for Agricultural Research, Hungarian Academy of
Sciences, 26-30 Nagykovácsi Road, H-1029, Budapest,
Hungary; 2Szent István University, Faculty of Veterinary
Science, 2 István street, H-1078, Budapest, Hungary
To combat plant viruses, a readily available option is to
suppress their insect vectors. Leafhoppers feed on plant sap
by penetrating their mouthparts into the plant while they
can transmit plant pathogens into them. This penetration
process can be monitored by Electrical Penetration Graph
(EPG) method. Predators can reduce population size of prey
by consuming them. However, non-consumptive effects
(NCEs)–like predator presence - may also decrease prey
fitness, e.g., by triggering physiological and behavioral
changes in prey animals, including escape behavior and
lowered feeding duration. NCEs were observed in two series of
experiments, where we used Psammotettix alienus (Cicadel-
lidae) as a leafhopper prey and the spider Tibellus oblongus
(Philodromidae) as a predator. First, we made an EPG setup
to record leafhopper penetration behavior in the presence of
the predator. Second, we made microcoms experiments, where
spiders were unable to catch leafhoppers, but leafhoppers
could sense spider presence. The EPG results showed that leaf-
hoppers responded to predation risk by extending the duration
of the mesophyll penetration phase, and also increasing its
recurrence, while the phloem ingestion phase was postponed,
appearing later in the feeding sequence than in the control
group. In mesocoms experiments we counted the number
of penetrations where salivary sheaths ended up in sieve
elements, and penetrations where salivary sheaths ended up
in mesophyll tissues after 24 hours. In full agreement with
the EPG studies, these results showed that in the presence of
spiders leafhoppers made penetrations to mesophyll tissues
in higher numbers than in the control group. Our novel
method to use EPG for the study of NCEs gave the opportunity
to make detailed, time-explicit observations on the feeding
behaviour of leafhoppers when exposed to predators and
showed that predators, like T. oblongus, can contribute to
biological control of plant pathogen vectors by their NCEs.
Keywords: leafhopper, spider, electrical penetration
graph (EPG) technique, non-consumptive effects
Student - oral presentation
Phylogeny, systematics and natural history
of pirate spiders (Araneae, Mimetidae)
*Ligia Rosario Benavides Silva1,2, Gonzalo Giribet2,
Gustavo Hormiga1
1Department of Biological Sciences, The George
Washington University Washington, D.C. 20052, USA;
2Museum of Comparative Zoology & Department
of Organismic and Evolutionary Biology, Harvard
48 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing