Although the Argentine ant has invaded most all the worlds regions with mediterranean and subtropical climates, several important aspects of its ecology are unpredictable: 1, its impact on seed dispersing ants, 2, its impact on nectar resources, and 3, the mechanisms that govern its spread through a landscape. I explored these aspects of the ant's ecology on the coast of central Chile and found 1. Argentine ants eliminate all native ants within fields and fragments of native forest except Solenopsis latastei. 2. While Solenopsis gayi and Pogonomyrmex ants remove seeds of 9/11 native plants from seed arenas, Argentine ants removed zero. 3. Flowers of the hummingbird pollinated Lobelia excelsa were strongly depleted of nectar by Argentine ants, but not by native ants. 4. Argentine ants are able to remove more nectar from L. excelsa chiefly because they persist at a much higher density than the native ants, and possibly because the most common native ants are too big to enter the nectar chamber of the flower. 5. Argentine ants invaded both hot dry fields and cool riparian sites. 6. Argentine ants invade the agro-ecological landscape by spreading through hedgerows and small clumps of native vegetation, and later invade overgrazed fields. 7. Until invaded, the dominant ant in these overgrazed fields (Solenopsis gayi) consumed seeds, and thus may have a trophic advantage over invading Argentine ants. 8. Argentine ants did not invade larger remnant forests (> 45m wide) that were often in ravines. I predict that Argentine ants will spread to most of the agro-ecosystems of the central coast of Chile. I propose that the spread of Argentine ants is limited by food availability, and that the hedgerows and patchy environments foster the ants invasion by fostering a variability in populations of insect prey, which the Argentine ant is adept at exploiting.
|School:||University of Washington|
|School Location:||United States -- Washington|
|Source:||DAI-B 73/02, Dissertation Abstracts International|
|Subjects:||Wildlife Conservation, Ecology, Entomology, Conservation|
|Keywords:||Argentine ant, Chile, Fragmentation, Invasive species, Linepithema humile, Pollination web, Sclerophyllous forests, Trophic interactions|
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