Jia-Wei Tay1, Mark S Hoddle1, Ashok Mulchandani2,3, Dong-Hwan Choe1. 1. Department of Entomology, University of California, Riverside, CA, USA. 2. Department of Chemical Engineering, University of California, Riverside, CA, USA. 3. Materials Science and Engineering Program, University of California, Riverside, CA, USA.
Abstract
BACKGROUND: Insecticide sprays used for ant control cause environmental contamination. Liquid bait is a safe and effective alternative, but it requires bait stations to dispense the toxicant. We developed a biodegradable hydrogel to deliver liquid bait obviating the need for bait stations. RESULTS: Alginate hydrogel beads with preferred rigidity and maximum hydration in 25% sucrose solution were engineered by optimizing a crosslinking process. The moisture content of the substrate on which the beads were placed and the relative atmospheric humidity significantly influenced water loss dynamics of the hydrated hydrogel beads. Laboratory choice studies indicated that hydrated hydrogel beads had reduced palatability to foraging ants when they lost ≥50% water. An enzyme-linked immunosorbent assay (ELISA) indicated that the insecticide thiamethoxam added to sucrose solution was absorbed into the hydrogel beads. Hydrogel beads conditioned in sucrose solution with 1 mg L-1 thiamethoxam provided complete control of all castes of Argentine ant Linepithema humile (Mayr) colony by 14 days post treatment in the laboratory trial and provided a 79% reduction in ant activity after 8 weeks in the field trial. CONCLUSION: Alginate hydrogel beads provided an effective delivery system for liquid baits laced with low concentrations of insecticide to control Argentine ants.
BACKGROUND: Insecticide sprays used for ant control cause environmental contamination. Liquid bait is a safe and effective alternative, but it requires bait stations to dispense the toxicant. We developed a biodegradable hydrogel to deliver liquid bait obviating the need for bait stations. RESULTS:Alginate hydrogel beads with preferred rigidity and maximum hydration in 25% sucrose solution were engineered by optimizing a crosslinking process. The moisture content of the substrate on which the beads were placed and the relative atmospheric humidity significantly influenced water loss dynamics of the hydrated hydrogel beads. Laboratory choice studies indicated that hydrated hydrogel beads had reduced palatability to foraging ants when they lost ≥50% water. An enzyme-linked immunosorbent assay (ELISA) indicated that the insecticide thiamethoxam added to sucrose solution was absorbed into the hydrogel beads. Hydrogel beads conditioned in sucrose solution with 1 mg L-1 thiamethoxam provided complete control of all castes of Argentine antLinepithema humile (Mayr) colony by 14 days post treatment in the laboratory trial and provided a 79% reduction in ant activity after 8 weeks in the field trial. CONCLUSION:Alginate hydrogel beads provided an effective delivery system for liquid baits laced with low concentrations of insecticide to control Argentine ants.