Photoreceptors and neural circuitry underlying phototaxis in insects

Visual behavior of insects has long been studied, but it is only recently that a wide variety of genetic tools have become available for its analysis. Perhaps the most basic visual behavior is phototaxis, locomotion towards a source of light. It is known in many insects and has been studied for over a century but the neural network underlying it is little understood. We recently described in the fruit fly Drosophila how different photoreceptor types contribute to phototaxis. By blocking subsets of them we showed that at least four of the five types are involved. In this short review, we compare phototactic behavior in fruit flies and other insects (especially honeybees), and discuss what is known about the underlying neural circuitry.