Visually guided homing in an understory-dwelling twig ant
Daniella C. Prince, Daniella C. Prince , Stephen P. Yanoviak
Department of Biology, University of Louisville, Louisville, KY, USA; Department of Biology, University of Louisville, Louisville, KY, USA ; Department of Biology, University of Louisville, Louisville, KY, USA
Sensory systems are essential to resource acquisition, interacting with conspecifics, and avoiding danger. Ants have sophisticated chemical and tactile senses, but the visual apparatus of many species also is engaged in complex behaviors. Tropical rain forest ants experience extreme light regimes from the bright canopy to the dim understory, potentially affecting the utility of visually guided behavior over evolutionary time. We examined the role of visual cues in the homing behavior of Pseudomyrmex boopis, a diurnal, understory twig-nesting ant with a canopy-nesting ancestor. We collected P. boopis workers from ten nests on Barro Colorado Island, Panama throughout the wet season in 2017. We painted over workers’ compound eyes and ocelli (blinded), or only their ocelli (blinkered), and measured their success in returning to their nest after being displaced 35cm. Fewer than 1% of blinded workers successfully returned to their nest entrance, and 28% of blinded workers were predated upon by either Odontomachus bauri or Ectatomma ruidum. Control and blinkered workers did not differ in their success of returning to the nest, and the time taken to return to the nest was the same across treatments. This suggests that P. boopis do not use olfaction for short-range homing, and ocelli are not involved in navigation at this scale. Despite living in the dark understory, the activity and success of P. boopis workers is bound by visual information perceived by their compound eyes. Visual sensing is often overlooked in ants; here we show that vision supersedes other senses in fundamental behaviors of a common tropical species.