Animal behaviour: At first sight

The visual system of Drosophila larvae can distinguish complex images of other writhing larvae, reports a study in Nature Communications this week. Drosophila - a widely used model for many basic human functions - were previously thought to have limited visual capabilities. However this work suggests that this may not be the case and therefore could lead to Drosophila being used in many more studies including those focussed on the complexities of developing visual systems.

Drosophila larvae have a small number of photoreceptors, which suggests that their capacity for visual processing should be limited. Barry Condron and colleagues develop a simple assay whereby they tether larvae to a surface and observe the behaviour of nearby freely foraging larvae. They find that the foraging larvae are attracted to the writhing tethered larvae, independent of olfactory cues, and that this behaviour could be replicated by playing movies of writhing larvae on a computer screen.

The authors conclude that although the visual system of the larvae is basic, further processing likely takes place in the relatively large central brain, to compensate for the simple input. They suggest that this ability to recognise other moving larvae may be required for cooperative behaviour, or an opportunistic attraction to a source of food.