Ants

I examined the impact of the exotic, invasive plant Old World climbing fern, Lygodium microphyllum (Cav.) R. Brown, on tree island plant and ant communities in the northern Everglades. I selected 15 tree islands representing four groups: non-Lygodium islands, islands with low levels of Lygodium, islands with high levels of Lygodium, and disturbed islands impacted by people. I used a variety of diversity indices to compare plant and ant data among habitats. The ant communities studied included native and exotic species typical of south Florida. Tree island plant communities were consistent with descriptions from previous studies. Plant species richness decreased with the level of L. microphyllum in the ground and midstory layers. Abundance of native plants decreased with level of L. microphyllum in the ground, midstory, and overstory layers. Lygodium microphyllum did not affect ant communities suggesting that although it negatively impacts plant communities it can provide habitat for ants.

Invasive ant species often show unicoloniality, forming networks of connected colonies (i.e. supercolonies), which may extend hundreds or even thousands of kilometers. These "supercolonies" lack intraspecific aggression, thus fighting between colonies is absent. Unicoloniality may be an adaptive mechanism that allows for invasive ant species to reach higher population density and achieve ecological dominance. We used aggression assays to study unicoloniality within and between colonies of the invasive brown rover ant, Brachymyrmex obscurior on the Florida Atlantic University campus in Jupiter, FL. We found that the four B. obscurior colonies could be behaviorally divided into two areas: workers from both colonies in either region never showed intraspecific aggression while workers from colonies in opposing areas always showed intraspecific aggression, often fighting to the death. Thus, B. obscurior appears to show very localized unicoloniality, with neighboring colonies forming small supercolonies.

Ants are ubiquitous and ecologically important, yet little is known of ants within Pakistan. I studied ants collected from houses and apartments in Karachi, Pakistan to determine which ants are common indoor ants. Ants were attracted by spilling syrups and sodas on the floor which were left overnight. The following morning the ants were collected using an aspirator. A total of eleven species were found. Of these eight were well-known pest ants with worldwide distributions: Paratrechina longicornis, Tetramorium simillimum, Monomorium pharaonis, Monomorium subopacum, Monomorium destructor, Tapinoma melanocephalum, Pheidole megacephala, and Tetramorium bicarinatum. Three others, Camponotus sp., Pheidole sp., and Solenopsis sp., not identified to species were probably native species. Paratrechina longicornis and M. subopacum were the two most dominant species that were found in the highest abundance.

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.

One mechanism allowing ant species to successfully invade new areas at a rapid pace is unicoloniality, the formation of large networks connecting colonies over hundreds or even thousands of kilometers. These large networks of colonies, or "supercolonies" lack any form of intraspecific aggression, thus fighting between them is absent. I used aggression assays to study unicoloniality between colonies of the invasive difficult ant, Technomyrmex difficilis on the Florida Atlantic University Wilkes Honors College campus and a household located ~32 km northwest from the college. I found that for all trial combinations, no aggression took place among the ants. From these results, I conclude that T. difficilis does display unicoloniality in South Florida.

Bioprospecting, the search for useful compounds in nature, has led to the discovery of many important pharmaceuticals. Most current bioprospecting efforts work with chemicals derived from marine invertebrates and terrestrial plants. I looked for useful compounds in a relatively unstudied source, the venom of Crematogaster ants, using Gas Chromatography-Mass Spectroscopy (GC-MS). Further studies can more accurately identify these chemicals using High Pressure Liquid Chromatography (HPLC) and Nuclear Magnetic Resonance (NMR).