Other organisms also appeared to be influenced
by the invasion of these ants. Observations
indicated that crab populations
were reduced, but not significantly so, in forested
areas invaded by A. gracilipes. Crab
densities can be reduced as a result of direct
predation (Green et al. 1999), although there
is some evidence that competition between
crabs and ants for food can also occur (Morrison
2002b). Elsewhere, isopod populations
have been observed to increase as a result
of the presence of A. gracilipes (Haines and
Haines 1978, Rao et al. 1989). Total insect
abundance was not significantly different
between sites, although there were very few
insects other than ants found in the pitfall
traps after only 24 hr. Elsewhere invasions
of A. gracilipes have been associated with reduced
densities of spiders and insects (Rao
et al. 1989, Gillespie and Reimer 1993), to the
point where these ants have been utilized for
biological control programs (Baker 1976).
In our Tokelau study, the lack of significant
effects for some of the groups could have