Walking While Parasitized: Effects of a Nematode Parasite on Locomotor Activity of Horned Passalus Beetles

Christopher Brandon, Andy Davis, Odum School of Ecology at the University of Georgia 140 E Green St, Athens, GA 30602

Parasites are typically thought to negatively affect their host by draining host resources and energy, thereby leading to reduction in overall activity. One little-studied nematode parasite, Chondronema passali, of the horned passalus beetle, Odontotaenius disjunctus may have the reverse effect; prior experiments have revealed that parasitized beetles actually consume more food than unparasitized individuals. This led us to question if parasitized beetles are also more physically active, and specifically, if their locomotor activity is heightened. We constructed a tabletop arena with individual grid squares to observe beetle locomotor activity. Using wild-caught beetles, we allowed individual beetles to traverse the arena for 5 minutes and recorded the number of grid squares crossed. Beetles were subsequently dissected to determine parasite presence and level of infection on a categorical scale. A total of 140 beetles were examined across three collection stages. Statistical analyses of locomotor activity revealed that the severity of parasite infection predicted locomotor activity, with lightly infected beetles twice as active as those without this parasite. Activity declined with increasing nematode burdens thereafter, but even the group with the most severe burdens did not move less than the group with no parasites.  From these results, we conclude that this parasite does not result in overall reduction in activity, but rather it appears to come with heightened locomotion, which is consistent with prior findings on host food consumption. Alternatively, this result could stem from the fact that more active beetles are simply more likely to contract the parasite. Regardless of the explanation, these results add to our understanding of how host behavior is impacted by parasites.  


Additional Abstract Information

Presenter: Christopher Brandon

Institution: University of Georgia

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4109