LAUSR

BACKGROUND Hydrogels that have absorbed a liquid containing a toxicant are a novel bait-delivery form for ant control. Here, we study the abilities of Argentine ant (L. humile) workers to imbibe liquid from hydrogels. We quantified feeding behavior with 1) hydrogels containing different sucrose concentrations (20, 30, 40, and 50%w/w), 2) hydrogels versus liquid droplets and 3) hydrogel age (time of air exposure). We also performed a field assay to assess visits of L. humile and other ant species to hydrogels. RESULTS Ingested volume and feeding time decreased with increasing sucrose concentrations, but the number and duration of pauses were similar. Feeding from hydrogels was slower than from a liquid droplet and ants imbibed less liquid and fed for shorter times from hydrogels. Feeding time increased with hydrogel age, whereas ingested volume decreased and approached zero after 120 min under laboratory conditions. In the field, ants attended the hydrogels during the full 120-min period. When L. humile workers found a hydrogel, they monopolized it to the exclusion of other ant species. L. humile occupied and dominated hydrogels predominantly in shaded locations. CONCLUSION Hydrogels with sucrose concentrations no greater than 30% appear best for liquid uptake for L. humile. Hydrogels not in direct sunlight will have greater attendance by L. humile and, therefore, less attendance by non-target ant species. Shady and humid places may prolong the longevity of hydrogels, which would imply higher intakes. This article is protected by copyright. All rights reserved.