title: Laboratory and Field Evaluations of Polyacrylamide Hydrogel Baits Against Argentine Ants (Hymenoptera: Formicidae).
abstract: The development of effective baits to control the Argentine ant, Linepithema humile (Mayr), has been problematic because foragers prefer sweet liquids, while many toxicants are insoluble in water and liquid baits are generally difficult to deliver. The incorporation of thiamethoxam and sucrose solutions into a water-absorbing polyacrylamide hydrogel provides a unique and novel carrier and method of application for liquid baits. Formulations of thiamethoxam affected the size of the hydrogels, and sucrose solutions containing 0.0003% technical thiamethoxam provided hydrogels as large as those made with 25% sucrose solution or deionized water. Concentrations of thiamethoxam as low as 0.000075% in the hydrogels provided 50% kill of workers within 3 d in a laboratory setting. In small colony studies, baiting with 0.00015 and 0.000075% thiamethoxam hydrogels provided 100% mortality of workers and queens within 8 d. An enzyme-linked immunosorbent assay indicated that thiamethoxam was absorbed into the interior of the polyacrylamide matrix. The water loss rates of the hydrogels were dependent upon the relative humidity. Polyacrylamide hydrogels with >50% water loss were less attractive to ants. Field studies in highly infested areas indicated that concentrations of 0.0006 or 0.0018% thiamethoxam were more effective than 0.00015%. Hydrogels may provide a cost-effective alternative to providing aqueous baits to control Argentine ants.
authors.affiliation: Department of Entomology, University of California Riverside, Riverside, CA 92521-0314. michael.rust@ucr.edu.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Rust
authors.affiliation: Department of Entomology, University of California Riverside, Riverside, CA 92521-0314.
authors.forename: Andrew
authors.initials: A
authors.lastname: Soeprono
authors.affiliation: Department of Entomology, University of California Riverside, Riverside, CA 92521-0314.
authors.forename: Sarajean
authors.initials: S
authors.lastname: Wright
authors.affiliation: Department of Entomology, University of California Riverside, Riverside, CA 92521-0314.
authors.forename: Les
authors.initials: L
authors.lastname: Greenberg
authors.affiliation: Department of Entomology, University of California Riverside, Riverside, CA 92521-0314.
authors.forename: Dong-Hwan
authors.initials: DH
authors.lastname: Choe
authors.affiliation: The Nature Conservancy, 532 E. Main St., Ventura, CA 93001.
authors.forename: Christina L
authors.initials: CL
authors.lastname: Boser
authors.affiliation: The Nature Conservancy, 532 E. Main St., Ventura, CA 93001.
authors.forename: Coleen
authors.initials: C
authors.lastname: Cory
authors.affiliation: California State University Channel Islands, Camarillo, CA 93012.
authors.forename: Cause
authors.initials: C
authors.lastname: Hanna
mesh_terms: D000180:Acrylic Resins; D000818:Animals; D001000:Ants / Q000254:growth & development; D003890:Desiccation; D007300:Insect Control; D007814:Larva / Q000254:growth & development; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D013395:Sucrose; D000077922:Thiamethoxam; D013844:Thiazoles
chemical_list: D000180:Acrylic Resins; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D013844:Thiazoles; C016680:polyacrylamide gels; D013395:Sucrose; D000077922:Thiamethoxam
keywords: Linepithema humile; polyacrylamide hydrogel; thiamethoxam