I'm a bit behind in posting David Holway's latest Argentine ant article, but here it is:

David A. Holway. 2004. Edge effects of an invasive species across a natural ecological boundary. Biological Conservation 121(4 ): 561-567.

Abstract
Natural habitats adjacent to human-modified areas often suffer edge
effects stemming from physical disturbance, elevated predator densities, or
invasive species. Although seldom documented, detrimental edge effects can also
occur at natural ecological boundaries. Here I examine the spatial pattern and
ecological effects of a biological invasion at well-delineated and abrupt edges
between riparian corridors and coastal sage scrub at 10 sites in southwestern
California. The invasive Argentine ant Linepithema humile thrives in moist
riparian corridors but decreases greatly in number with increasing distance into
adjacent dry scrub habitats. As L. humile numbers decrease, both the number of
native ant workers and the number of native ant species captured in pitfall
traps increase. Argentine ants appear to suppress native ants within at least 50
m of riparian corridors, but these effects diminish to undetectable levels by
200 m. At comparable uninvaded sites neither the number of native ant workers
nor the number of native ant species captured in pitfall traps varies
significantly across riparian-scrub edges. Areas subject to this edge effect may
be sinks both for native ants and for organisms that depend on them for food or
services. In general edge effects occurring at natural boundaries should receive
increased attention as they might disrupt ecosystems not greatly altered by
human activity.