Navigation system of the ant Myrmica rubra (Hymenoptera: Formicidae)

Cammaerts, M.-C.

Abstract: Foragers of Myrmica rubra were differentially conditioned to two olfactory and two visual cues. Their response to the visual cues was slight under light conditions at 110 lux. Conditioned workers negotiated mazes that were adequately provided with either olfactory or visual, or two kinds of cues. Under low light intensity, they performed better in presence of olfactory elements than in presence of visual cues and their performance was perfect when tested in presence of both two kinds of cues. They thus used similarly learned visual and olfactory cues; however, under low light intensity, they see poorly, thus rely less on visual cues than on olfactory cues. Indeed, in mazes provided with correct visual and incorrect olfactory cues, M. rubra workers were unable to find their way at 330 lux. At 110 lux, they incorrectly negotiated the mazes, since they could only slightly perceive the correct cues while perception of the incorrect cues was strong. In mazes provided with incorrect visual and correct olfactory cues, M. rubra workers again failed to find their way at 330 lux, since they perceived both correct and wrong cues simultaneously. At 110 lux, they correctly negotiated the mazes, since they slightly perceived the incorrect cues and strongly perceived the correct cues. In a final experiment, performed under very low light intensity and using mazes differently provided with cues, the previous results were confirmed. To summarize the navigation system of M. rubra foragers, it can be stated that these ants rely equally, as best as they can, on visual and olfactory cues. This conclusion is in agreement with the species' eye morphology, visual perception and usual biotope. The present work closes a series of studies on the visual and navigation system, as well as the biotope and eye morphology of M. sabuleti, M. ruginodis and M. rubra workers.

Myrmecol. News 16: 111-121; printable