Technical Report #173.
Krushelnycky, P.D., W. Haines, L. Loope and E. Van Gelder. 2011. The
Haleakala Argentine ant project: a synthesis of past research and
prospects for the future
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1. The Haleakala Argentine Ant Project is an ongoing effort to study the
ecology of the invasive Argentine ant in the park, and if possible to
develop a strategy to control this destructive species.
2. Past research has demonstrated that the
Argentine ant causes very significant impacts on native arthropods where
it invades, threatening a large portion of the park's biodiversity in
subalpine shrubland and alpine aeolian ecosystems.
3. Patterns of spread over the past 30+
years indicate that the invasion process is influenced to a substantial
degree by abiotic factors such as elevation, rainfall and temperature,
and that the ant has not reached its potential range. Predictions of
total range in the park suggest that it has only invaded a small
fraction of available suitable habitat, confirming that this species is
one of most serious threats to the park's natural resources.
4. Numerous experiments have been conducted
since 1994 in an attempt to develop a method for eradicating the
Argentine ant at Haleakala using pesticidal ant baits. Thirty baits have
been screened for attractiveness to ants in the park, and ten of these
were tested for effectiveness of control in field plots. While some of
these baits have been very effective in reducing numbers of ants, none
has been able to eliminate all nests in experimental plots.
5. Research into a secondary management goal
of ant population containment was initiated in 1996. By treating only
expanding margins of the park's two ant populations with an ant
pesticide, rates of outward spread were substantially reduced in some
areas. While this strategy was implemented from 1997 to 2004, it was
ultimately discontinued after 2004 because of the difficulty and
insufficient effectiveness of the technique.
6. In order to achieve the types of
results necessary for eradication, the project would probably need to
explore the possibility of developing a specialized bait, rather than
relying on a commercially produced bait. An alternative would be to
pursue approval to use Xstinguish bait, a commercial bait manufactured
in New Zealand and not registered for use in the US, which has yielded
good results against Argentine ants. Either route
would involve significant regulatory hurdles. Because the baits
ultimately used would likely be liquid or paste in form, there would
also be major logistical challenges in devising methods to successfully
apply the baits across the two large ant populations at Haleakala.