Color discrimination and preference in the fire ant Solenopsis invicta Buren

Ants generally use chemoreception more than vision to obtain information about their environment. However, available genome sequences suggest that color vision is possibly widespread in ants. In this study, responses of workers of the fire ant Solenopsis invicta Buren in dual choice conditions for differently colored glass bead pairs were tested. Workers from ten colonies were randomly selected and allowed to perform digging behavior in an apparatus filled with colored glass beads in paired choice tests for 1 h. In the experimental group, workers dug in light conditions, while in the control group, workers dug in the dark. Glass beads consisted of five colors: blue, green, yellow, orange, and red. The number of glass beads brought to the surface was recorded and used as indication of preference of workers. Results indicated that workers significantly preferred one or more colors over alternatives and they had a general preference for relatively longer wavelengths compared to shorter wavelengths. Comparison of the estimated absorbed light intensity with the bead choices showed that workers generally preferred beads that transmitted less light. However, although the absorbed intensity was the same for blue and green beads, the workers had a significant preference for green beads, thereby clearly showing color discrimination. It was also observed that workers dug more in the light compared to the dark conditions. Results of this study can be used to improve the attractiveness of fire ant baits by exploiting their color preferences. The possibility of S. invicta using color vision and areas to further explore are discussed.