2985 St. Rd 29 N. Immokalee FL 34142. Red imported fire ant (RIFA) Solenopsis invicta Buren. The trial was conducted at the Southwest Florida Research and ...
Arthropod Management Tests 2010, Vol. 35
doi: 10.4182/amt.2010.D12
D12 ORANGE: Citrus sinensis (L.) Osbeck, ‘Valencia’ CONTROL OF RED IMPORTED FIRE ANT ON CITRUS BEDS IN SOUTHWEST FLORIDA WITH TOXIC BAITS. P.A. Stansly & G. L. Fulcher University of Florida/IFAS Southwest Florida Res. & Ed. Ctr. 2985 St. Rd 29 N Immokalee FL 34142 Red imported fire ant (RIFA) Solenopsis invicta Buren The trial was conducted at the Southwest Florida Research and Education Center in Immokalee on 24 unplanted citrus beds, 28 ft wide separated by 16 ft swales with 3ft between bed tops and swale bottoms according to standard local practices. Beds were newly made and that most, if not all RIFA colonies were of recent origin, including new mounds appearing toward the end of the trial. Treatment plots consisted of 3 adjacent sections of bed 200 ft length with only the middle bed section used for sampling. Experimental design was replicated complete block with 4 replications and 4 treatments applied at 1 lb/acre: Ascend (0.011% abamectin), Logic (1% fenoxycarb), Amdro (0.73% hydromethylnon), AC303-630 (0.005%), a 5th treatment, Bushwacker (18% boric acid) applied at 3 lb/ac, and an untreated control. Ant baits were spread over a 30 ft swath from the center of the beds with a Herd GT-77A seeder spreader mounted on a Ford tractor on 3 July 1996 at 5:00-8:30 p.m. Pre-counts taken on 2 Jul consisted of a complete census of active mounds and a count of ant captured with a peanut butter bait. Mounds were counted and baits were placed within the central 100 ft of the central bed along an 8 ft herbicided band centered 3 ft from on the edge of the bed. Mounds were considered active if ants could be observed following a gentle disturbance. Large (500mm) petri plates were used as bait stations, filled with 10 g of peanut butter and placed out into the sampling area in the evening to be collected the next morning and placed into the freezer for a minimum two hours. Fire ants caught in the petri dishes were then counted and for the last 4 post-treatment counts ants were also weighed as was the remaining peanut butter so that consumption could be estimated. A total of 5 post-treatment samples were taken on 24 Jul, 14 Aug, 4 Sep, 16 Oct and 13 Nov. Significant differences in numbers of active mounds were seen on 14 Aug and in subsequent observations. Lowest counts on 14 Aug were seen in plots treated with Amdro I, although not significantly different from ASCEND (Table 1). There were fewer mounds in all treatments compared to the control except for Bushwacker. On 4 Sep, all treatments except Bushwacker had fewer mounds than the control, and there were no significant differences among remaining treatments. On 16 Oct there were fewest active mounds in plots treated with Logic, but not significantly different from ASCEND or Amdro I. AC303-630 and Bushwacker were not significantly different from the control. On 13 Nov, plots treated with ASCEND, Logic and Amdro I had fewer mounds than plots treated with AC303630, Bushwacker or untreated. Significant differences in ant numbers on peanut butter baits were observed on 24 July, 16 Oct. and 13 Nov. On 24 Jul, plots treated with Amdro I and ASCEND had fewer ants than the remaining treatments and the control (Table 2). On 13 Oct, only Bushwacker was not significantly different from the control and there were no significant differences between remaining treatments. Results were similar on 13 Nov except that neither Amdro treatment was different from the control. Significant treatment effects with regards to ant weight were seen only on 16 Nov when Bushwacker and AC303-630 were not different from the control and there were no significant differences between remaining treatments (Table 3). Significant differences in bait loss were seen the last 3 sample dates. On 4 Sep, less peanut butter was lost from dishes in Bushwacker-treated plots compared to all other treatments including the control. On 16 Oct, no measurable amount of bait was left in dishes on Logic-treated plots, although this was not significantly different from other treatments except for Bushwacker and the control. On 13 Nov, least bait loss occurred in plots treated with Logic and ASCEND but not less than Amdro I, and there were no differences between the other two treatments and the control. This parameter appeared to be the most dependable for evaluating fire ant activity although all 5 parameters evaluated were generally in agreement and allowed for some clear distinctions to be drawn regarding the activity of the products tested. Amdro clearly worked most rapidly but also had somewhat less residual than Logic and ASCEND which tended to act longer. The Amdro I formulation was clearly better than AC303-630. Little if any activity was seen from Bushwacker.
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Arthropod Management Tests 2010, Vol. 35
doi: 10.4182/amt.2010.D12
Table 1. Mean number of RIFA mounds per 100 ft of bed. 24JUL96 Ascend Logic Amdro_I Ac606-330 Bushwacker Untreated
12.00 11.50 6.75 10.75 11.25 15.00
14AUG96 1.50dc 3.50abc 0.25d 2.75bc 4.75ab 5.25a
04SEP96
16OCT96
1.00b 1.00b 0.50b 0.25b 4.50a 3.25a
1.75c 0.25c 2.50bc 5.25ab 8.50a 7.25a
13NOV96 7.25b 5.25b 7.25b 10.50a 10.75a 11.25a
Table 2. Mean number of RIFA per 500 mm petri dish bait station (N = 5 per plot). 24JUL96 Ascend Logic Amdro_I Ac606-330 Bushwacker Untreated
22.75b 101.00a 9.35b 143.80a 119.60a 120.15a
14AUG96
04SEP96
16OCT96
101.25 110.35 48.00 8.80 3.85 46.40
57.55 0.85 55.40 44.65 120.80 37.45
4.30b 0.05b 38.00b 40.55b 240.55a 183.65a
13NOV96 69.50a 59.95a 96.95ab 152.55ab 188.40b 180.95b
Table 3. Mean weight in grams of ants per 500 mm petri dish bait station. 4AUG96 Ascend Logic Amdro_I Ac606-330 Bushwacker Untreated
0.315 0.411 0.214 0.026 0.018 0.158
04SEP96 0.368 0.008 0.237 0.103 0.126 0.182
16OCT96
13NOV96
0.069 0.000 0.468 0.296 0.577 0.514
0.192b 0.215b 0.230b 0.323ab 0.397a 0.376a
Table 4. Mean overnight loss (g) from 10 g peanut butter bait due to ant feeding. 14AUG96 Ascend Logic Amdro_I Ac606-330 Bushwacker Untreated
2.074 1.137 1.939 0.504 0.196 0.836
04SEP96
16OCT96
13NOV96
0.773b 0.204b 0.263b 1.188b 2.612a 0.595b
0.069c 0.000c 0.328bc 0.921bc 2.262a 1.534ab
0.743c 0.527c 1.550bc 2.513ab 3.309a 3.346a
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