PARENT SESSION
Oral Session # 59: Mutualism - Parasitism II: Animal and Insect.
Presiding: L Cochran-Stafira
Wednesday, August 6. 1:30 PM to 5:00 PM, SITCC Meeting Room 203.
The effect of a trematode parasite on the response of a snail to light and gravity.
Levri, Edward*,1, Itle, Carolyn1, Lunnen, Shane1, Winters, Justin1, Platt, Robert 1, 1 Division of Mathematics and Natural Science, Altoona, PA, USA
ABSTRACT- Parasites often influence the behavior of their hosts in ways that increase the transmission rate of the parasite. The New Zealand snail, Potamopyrgus antipodarum, is commonly infected with the trematode Microphallus sp. Infected snails must be eaten by waterfowl for transmission of the parasite to occur. Previous studies from Lake Alexandrina, South Island, New Zealand, have demonstrated that infected snails are more exposed to predators on top of rocks in the early morning, when waterfowl are feeding, than uninfected snails. Infected snails then move to safer locations beneath rocks when non-host predators (fish) begin to feed later in the day. The mechanism by which the parasite alters behavior is not clear. These experiments, conducted in the field and in the lab, were designed to determine the effect of the parasite on specific behaviors. Here we examine the geotactic and phototactic behaviors of infected and uninfected snails. Snails were placed in behavioral arenas. In the geotactic experiments the arenas were moved into a vertical position, and snails were collected after four minutes and separated by whether they moved up or down. In the phototactic experiments, snails responded to a directional light source and were separated after four minutes by their angle of orientation. All snails were measured and dissected to determine gender, brooding condition, and parasitism. All groups of snails were found to be positively geotactic, however, infected snails responded significantly less than any other snail group. Snails were also found to be weakly positively phototactic, however, there were not enough infected snails to determine if the parasite influenced this behavior. These results may help to explain how the parasites influences the behavior or the snail in a time-specific manner.
Key words: behavior, parasite , snail, Potamopyrgus antipodarum