Ocelli in walking insects: insights from day and night active bull ants

A project undertaken at the Department of Biological Sciences, Macquarie University and supervised by Dr Ajay Narendra and Dr Yuri Ogawa

In addition to the compound eye, most flying insects have simple eyes known as ocelli. These are placed in a triangular formation on the dorsal surface of the head and assist insects in in flight stabilisation, horizon detection and orientation. Among ants, typically the flying alates have ocelli while the pedestrian workers lack this structure. The Australian ant genus Myrmecia is one of the few ant genera in which the walking workers have three ocellar lenses. In addition, sympatric species of Myrmecia operate at discrete times of the day, allowing us to identify how the structure and function of ocelli has evolved for a bright and dimly lit world.

The objective of our project is to identify the functional significance of ocelli in walking insects such as ants. We aim to address this as follows:

  1. Behavioural function of the ocelli. To rigorously test behaviourally the function of the ocelli in day- and night-active ants.
  2. Structure and neural architecture of ocelli. To identify the structure and neural pathway of ocelli in workers active at different times of the day.
  3. Developing the Ant Ocelli Database. To bring together ecological, behavioural, morphological and physiological data to identify for the first time why the simple eye is present in some ant species across the ant phylogeny.
References

Narendra A & Ribi WA. 2017. Ocellar structure is driven by the mode of locomotion and activity time in Myrmecia ants. Journal of Experimental Biology 220: 4383-4390.


Figure 1. Night-active ants have larger ocelli in Myrmecia ants. Top: day-active ant, Myrmecia croslandi. Bottom: night-active ant, Myrmecia pyriformis.