Laboratory and Field Evaluation of Granular Ant Baits and The Attractiveness of Liquid Ant Bait, 1996

Abstract

Efficacy tests were conducted on two sets of three colonies each of S. invicta and M. pharaonis. An additional colony of each species was held as an untreated control. Each test was replicated three times. Two g of either Ascend PT-370 (modified granular ant bait [.011% Abamectin]) or Maxforce granular ant bait (Hydramethylnon 1 %) were given to each of three colonies in each set, respectively, at the start of the test. Prior to starting the test, all colonies were deprived of food for 48h, to ensure the ants would be hungry. Control colonies were fed the regular laboratory diet . . . live yellow meal-worms for S. invicta and frozen field crickets for M. pharaonois. At the end of 48h bait exposure, bait dishes were removed and reweighed. The amount of bait removed determined the relative attractiveness of the baits. Mortality counts were made beginning 1 wk posttreatment, then weekly for 8 wk. Field tests to determine the attractancy of the experimental ant bait TC-93 to colonies of P. longicornis were conducted on three busy foraging trails. Three active S. invicta mounds were used to test the attractancy of TC-93 to red imported fire ants. These tests were conducted by placing lg of TC-93 liquid ant bait in the center of 4 X 5 inch note cards, and placing a baited card on each of 3 busy P. longicornis forging trails. At TC-93 baited card was also placed at the bases of 3 active S. invicta mounds. Counts of ants visiting these stations were made over a 2-min period at 10, 30, and 60 min. following bait placement. The number of ants responding determined the relative attractiveness to the ants. Tests were conducted at Moody Gardens, Galveston, TX to determine the relative attractiveness of the TC-93 ant bait to Ghost ants, and to compare the measured response to that stimulated by the granular ant baits Maxforce and Ascend PT-370 modified bait. These tests utilized 24 bait stations: 8 stations contained 1 g each TC-93; 8 contained 1 g each Maxforce; 8 contained 1 g each Ascend PT-370 (modified) ant bait. These stations were clear, covered plastic petri dishes (35mm X 10mm) with lids removed to accommodate ant entry. These stations were alternately placed about lm apart in areas where ants were seen. Ghost ants (and other species) were counted at the bait stations 30 min after placement. A final count was made 2h post-treatment. Bait stations were then picked up and returned to the lab and reweighed to determine the amount of bait removed to assess and compare the relative attractiveness of each bait.