Higher densities of S. invicta in the United States relative to South America are
explained mainly by the absence of natural enemies and low interspecific competition
(IC). Despite advances in S. invicta management, broadcast insecticide baits remain as
the primary tool for effective control. I studied interspecific interactions of ants and the
use of baits on the management of S. invicta to test the following hypotheses: 1) relative
abundance of native ants increases ~25% for bait treated sites compared to untreated, 2)
behavioral dominance by S. invicta decreases ~10% in bait treated sites compared to
untreated, and, 3) foraging by S. invicta on insecticide baits is higher ~10% in low native
ant densities areas compared to high densities.
Experiments were conducted on three sites with different densities of native ants
(low, medium, high), but with similar densities of S. invicta. An enhanced BACI
(Before/After-Control/Impact) design was used. Experimental units consisted of 0.4 ha
plots. Three treatments were randomly assigned to units and replicated four times; 1)
Slow acting bait, 2) Fast acting bait, 3) Untreated Control. Samples and observations
were collected for several weeks before/after the treatments to account for temporal variation and to determine rates of reinvasion. Ants were monitored using pitfalls and
food lures. Interspecific competition was determined by applying placebo bait. Results
indicate that different management methods did not impact resident ants when they are
at low and medium densities and that S. invicta is greatly affected; at high native ant
density, competition for these baits is observed affecting both natives and S. invicta.
Reinvasion of S. invicta was reduced in areas of low and medium native ant densities
previously treated with baits and native ant abundance increased by ~25%. At high
native ant densities, reinvasion of S. invicta was similar to Control sites. I conclude: 1)
properly used, baits can help in recovery of native ant species that then compete with S.
invicta; however, rote re-treatments may have a negative impact on restored populations.
2) “bait failures” may be due to interspecific competition when initial native ant
densities are high. Preliminary management considerations and recommendations are
presented.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2956 |
| Date | 15 May 2009 |
| Creators | Calixto, Alejandro Antonio |
| Contributors | Harris, Marvin K. |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | electronic, application/pdf, born digital |
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