Host-parasite relationships

Pleurogonius malaclemys is a digenean trematode with a life cycle that begins in Ilyanassa obsoleta as a first and second intermediate host and Malaclemys terrapin as a definitive host. The fluke matures and reproduces within terrapins and, therefore, relies on terrapins for dispersal. Thus, we hypothesized that the genetic structure of flukes would reflect contemporary changes in the connectivity of terrapin populations. Flukes were sampled by dissecting mudsnails collected from eight sites along the eastern United States. Following amplification of the COI mitochondrial marker, 21 haplotypes were identified and a high degree of structure was detected. We propose that this suggests the parasite could serve as a tool for monitoring terrapin populations. This study sets a foundation for the genetic diversity of the fluke, and provides a first step towards developing the species as a proxy for studying terrapin population size, connectivity, and health, which may help conserve both species.

This study was designed to determine the sensory basis
of host location by the pearlfish, Carapus bermudensis
(Jones). Forty-eight hour aquaria observations and
examination of stomach contents revealed that pearlfish
emerge, probably nightly, shortly after dark and feed
on small crustaceans. Experiments in a two-way choice
apparatus demonstrate that pearlfish locate the host
holothurian, Actinopyga agassizi (Selenka), by olfaction.
Vision and rheotaxis are not used as alternative methods
of' host location or in conjunction with olfaction. These
findings are analyzed in terms of the present knowledge
of sensory competence in fish.

The pyramid ant, Dorymyrmex bureni, is one of the most common and conspicuous ants of open, sandy habitats in the southeastern US. To examine the architecture of D. bureni nests in different habitats, I made wax casts of the subterranean tunnels and chambers of nests in a disturbed college campus site (n=3) and a relatively undisturbed greenway preserve site (n=5). Nests of pyramid ant, Dorymyrmex bureni, consist of two basic units : horizontal chambers and descending shafts connecting them. Chambers near the surface are tunnel-like with branches arranged in a nexus, while deeper chambers were more compact in outline. Chamber height is more or less constant, but chamber shape becomes more complex and lobed in characteristic ways as chambers enlarge. Nests have a top-heavy distribution of chamber area at all sizes because chambers are larger and closer together in the upper nest regions.