Hydrogel feeding – laboratory and field assays using the Argentine ant

In the recent article “Laboratory and field insights into the dynamics and behavior of Argentine ants, Linepithema humile, feeding from hydrogels” published in Pest Management Science, Emilia Cabrera, Ignacio Rivas Fontan, Benjamin D Hoffmann, and Roxana Josens investigated the abilities of L. humile workers to imbibe liquid from hydrogels, a hydrophilic polymer that does not dissolve in water but is highly absorbent. They quantified feeding behaviours from hydrogel varying in sucrose concentration, exposure time, etc. They revealed that hydrogels with a sucrose concentration no greater than 30% yielded the highest liquid uptake. In a field assay, Argentine ants discovered only hydrogels that were not in direct sunlight. In those cases, they dominated and monopolized the resource. Here, Roxana, Emilia, and Ignacio share some pictures.

A Photoblog contribution by Emilia Cabrera, Roxana Josens, and Ignacio Rivas Fontan

All pictures are © Emilia Cabrera

A station used in the study, which consisted of a flat white plastic in which center was located a half bead of hydrogel soaked in sugar solution. Ants that visited the station and fed on the hydrogel, either the Argentine ant or other ants (identified down to genus or species) were recorded for two hours.

Argentine ants, L. humile, feeding on half a bead of hydrogel soaked in a sugary solution. Hydrogels not exposed to direct sunlight had a higher presence of L. humile, which dominated these stations quickly after being discovered.

Brachymyrmex sp. ants feeding on sugar solution contained in a half bead of hydrogel offered on a white plate.

Solenopsis sp. ants at the station near the hydrogel bead.

Photo 6: Crematogaster sp. ants feeding on a sugary drop that fell on the grass while preparing the station for the study.

One of the study areas within the campus of the University of Buenos Aires.

Linepithema humile ant under the magnifying glass, feeding on a small piece of hydrogel soaked in sucrose solution.