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EFFICACY OF S-METHOPRENE ANT BAITS TO CONTROL THE LITTLE FIRE ANT, 2011

EFFICACY OF S-METHOPRENE ANT BAITS TO CONTROL THE LITTLE FIRE ANT, 2011 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.L1 (L1) BIOASSAY Arnold H. Hara Plant and Environmental Protection Sciences University of Hawaii at Manoa Komohana Research and Extension Center 875 Komohana St. Hilo, Hawaii 96720 Phone: (808) 981-5199 Fax: (808) 981-5211 e-mail: arnold@hawaii.edu Susan K. Cabral e-mail: susancab@hawaii.edu Kris L. Aoki e-mail: krisaoki@hawaii.edu Little fire ant (LFA): Wasmannia auropunctata The purpose of this experiment was to compare the efficacy of S-methoprene baits to control little fire ant (LFA). The trial was conducted at the University of Hawaii at Hilo, College of Agriculture, Forestry and Natural Resource Management instructional farm near Hilo, Hawaii from Jul 8 through Oct 31, 2011. Baits tested were: Extinguish Professional (0.50% S- methoprene) in soybean oil corn grit, two concentrations of Tango (0.25% and .50% S-methoprene) in a peanut butter mixture, and an untreated peanut butter check. All treatments were replicated five times in a RCB design. Ants were collected from the field 3 to 4 weeks prior to the trial. Two weeks before exposure to baits, LFA workers were transferred to 5.7 liter plastic boxes with internal walls coated with fluon and an insect trapping adhesive applied just inside the container rim to form a 0.5 cm wide barrier; queens were transferred 10 days later. Colonies consisted of approximately 250 workers and one queen. A polystyrene petri dish (60 mm diameter x 15 mm ht) containing a cotton ball moistened with water to maintain humidity was placed at one end of each colony’s box to serve as a nest; the lid was darkened with black spray paint. Ants in all treatments were fed a diet of peanut butter, soybean oil, and sugar water (10% w/v); the feeding station was situated on the opposite end of the box from the nest. The colonies were maintained in a roofed, screen-house with natural sunlight. During the trial, the average temperature was 74.0°F (23.3°C) (range 67.6°F (19.8°C) to 81.5°F (27.5°C)); average relative humidity was 70.6% (range 24.0 to 96.4%). All food was removed three days prior to bait exposure; water was provided throughout this fasting period. Each bait treatment (1.2 ml) was measured onto a plastic vial lid (30 mm diameter x 5 mm ht) and placed at the feeding station end of each colony’s box. Food was returned to the feeding station 24 h after bait introduction and changed weekly; original baits remained unchanged in the feeding station for four weeks; then, replaced with fresh baits and removed at eight weeks. Observations of ant mortality were recorded 1, 2, 3 and 4 h after treatment, at 1, 2, 3, 4, 7, 9, and 11 day after treatment, then at weekly intervals from 2 to 16 weeks after treatment (WAT). Digital photographs of each colony documented live and dead ant counts, which were completed in the lab. Ant mortality for each bait treatment was corrected for mortality among the checks using Abbott’s formula, then arcsine transformed prior to statistical analysis (ANOVA, Tukey’s test to separate difference among treatment means). There were no differences in mortality between treatments and the check until 12 WAT when mean percent mortality in Extinguish Professional and both Tango treatments exceeded 80% (Table 1). However, Tango and Extinguish Professional were not different from each other. By 16 WAT all treatments’ mean percent mortality exceeded 95% with both Tango treatments achieving 99% mortality. Although there was no difference between treatments, a field trial measuring bait attractiveness to LFA, indicated a preference for the untreated check and Tango at both 0.25% and 0.50% S-methoprene while ants displayed almost 100% aversion toward Extinguish Professional. Evidently, the high attractancy of peanut butter in Tango offset repellency to 0.50% S-methoprene unlike Extinguish Professional’s formulation with soybean oil. High 1 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.L1 mortality among checks at 12 WAT and 16 WAT (44.85% and 68.22%, respectively) may be attributed to natural attrition within the colonies and fecundity of the queen because ants were of unknown age when field-collected prior to the start of the trial. Table 1. % Mortality means* Rate 08-July 08-Aug 06-Sept 03-Oct 31-Oct Treatment (% S-methoprene) 0 WAT 4 WAT 8 WAT 12 WAT 16 WAT Check 0.00 0.0 13.8a 27.4a 44.9a 68.2a Extinguish Professional 0.50 0.0 18.1a 40.1a 84.3b 97.9b Tango 0.25 0.0 11.4a 24.6a 88.3b 99.4b Tango 0.50 0.0 25.3a 47.0a 90.3b 99.1b Means within each column followed by the same letter are not significantly different (Tukey’s, P>0.05). http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Arthropod Management Tests Oxford University Press

EFFICACY OF S-METHOPRENE ANT BAITS TO CONTROL THE LITTLE FIRE ANT, 2011

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10.4182/amt.2013.L1
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Abstract

Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.L1 (L1) BIOASSAY Arnold H. Hara Plant and Environmental Protection Sciences University of Hawaii at Manoa Komohana Research and Extension Center 875 Komohana St. Hilo, Hawaii 96720 Phone: (808) 981-5199 Fax: (808) 981-5211 e-mail: arnold@hawaii.edu Susan K. Cabral e-mail: susancab@hawaii.edu Kris L. Aoki e-mail: krisaoki@hawaii.edu Little fire ant (LFA): Wasmannia auropunctata The purpose of this experiment was to compare the efficacy of S-methoprene baits to control little fire ant (LFA). The trial was conducted at the University of Hawaii at Hilo, College of Agriculture, Forestry and Natural Resource Management instructional farm near Hilo, Hawaii from Jul 8 through Oct 31, 2011. Baits tested were: Extinguish Professional (0.50% S- methoprene) in soybean oil corn grit, two concentrations of Tango (0.25% and .50% S-methoprene) in a peanut butter mixture, and an untreated peanut butter check. All treatments were replicated five times in a RCB design. Ants were collected from the field 3 to 4 weeks prior to the trial. Two weeks before exposure to baits, LFA workers were transferred to 5.7 liter plastic boxes with internal walls coated with fluon and an insect trapping adhesive applied just inside the container rim to form a 0.5 cm wide barrier; queens were transferred 10 days later. Colonies consisted of approximately 250 workers and one queen. A polystyrene petri dish (60 mm diameter x 15 mm ht) containing a cotton ball moistened with water to maintain humidity was placed at one end of each colony’s box to serve as a nest; the lid was darkened with black spray paint. Ants in all treatments were fed a diet of peanut butter, soybean oil, and sugar water (10% w/v); the feeding station was situated on the opposite end of the box from the nest. The colonies were maintained in a roofed, screen-house with natural sunlight. During the trial, the average temperature was 74.0°F (23.3°C) (range 67.6°F (19.8°C) to 81.5°F (27.5°C)); average relative humidity was 70.6% (range 24.0 to 96.4%). All food was removed three days prior to bait exposure; water was provided throughout this fasting period. Each bait treatment (1.2 ml) was measured onto a plastic vial lid (30 mm diameter x 5 mm ht) and placed at the feeding station end of each colony’s box. Food was returned to the feeding station 24 h after bait introduction and changed weekly; original baits remained unchanged in the feeding station for four weeks; then, replaced with fresh baits and removed at eight weeks. Observations of ant mortality were recorded 1, 2, 3 and 4 h after treatment, at 1, 2, 3, 4, 7, 9, and 11 day after treatment, then at weekly intervals from 2 to 16 weeks after treatment (WAT). Digital photographs of each colony documented live and dead ant counts, which were completed in the lab. Ant mortality for each bait treatment was corrected for mortality among the checks using Abbott’s formula, then arcsine transformed prior to statistical analysis (ANOVA, Tukey’s test to separate difference among treatment means). There were no differences in mortality between treatments and the check until 12 WAT when mean percent mortality in Extinguish Professional and both Tango treatments exceeded 80% (Table 1). However, Tango and Extinguish Professional were not different from each other. By 16 WAT all treatments’ mean percent mortality exceeded 95% with both Tango treatments achieving 99% mortality. Although there was no difference between treatments, a field trial measuring bait attractiveness to LFA, indicated a preference for the untreated check and Tango at both 0.25% and 0.50% S-methoprene while ants displayed almost 100% aversion toward Extinguish Professional. Evidently, the high attractancy of peanut butter in Tango offset repellency to 0.50% S-methoprene unlike Extinguish Professional’s formulation with soybean oil. High 1 Arthropod Management Tests 2013, Vol. 38 doi: 10.4182/amt.2013.L1 mortality among checks at 12 WAT and 16 WAT (44.85% and 68.22%, respectively) may be attributed to natural attrition within the colonies and fecundity of the queen because ants were of unknown age when field-collected prior to the start of the trial. Table 1. % Mortality means* Rate 08-July 08-Aug 06-Sept 03-Oct 31-Oct Treatment (% S-methoprene) 0 WAT 4 WAT 8 WAT 12 WAT 16 WAT Check 0.00 0.0 13.8a 27.4a 44.9a 68.2a Extinguish Professional 0.50 0.0 18.1a 40.1a 84.3b 97.9b Tango 0.25 0.0 11.4a 24.6a 88.3b 99.4b Tango 0.50 0.0 25.3a 47.0a 90.3b 99.1b Means within each column followed by the same letter are not significantly different (Tukey’s, P>0.05).

Journal

Arthropod Management TestsOxford University Press

Published: Jan 1, 2013

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