Aggression and social experience: genetic analysis of visual circuit activity in the control of aggressiveness in Drosophila

BACKGROUND: Animal aggressiveness is controlled by genetic and environmental factors. Among environmental factors, social experience plays an important role in modulating aggression in vertebrates and invertebrates. In Drosophila, pheromonal activation of olfactory neurons contributes to social suppression of aggression. While it was reported that impairment in vision decreases the level of aggression in Drosophila, it remains unknown if visual perception also contributes to the modulation of aggression by social experience. RESULTS: In this study, we investigate the role of visual perception in the control of aggression in Drosophila. We took several genetic approaches to examine the effects of blocking visual circuit activity on fly aggressive behaviors. In wild type, group housing greatly suppresses aggressiveness. Loss of vision by mutating the ninaB gene does not affect social suppression of fly aggression. Similar suppression of aggressiveness by group housing is observed in fly mutants carrying a mutation in the eya gene leading to complete loss of eye. Chronic visual loss does not affect the level of aggressiveness of single-housed flies that lack social experience prior to behavioral tests. When visual circuit activity is acutely blocked during behavioral test, however, single-housed flies display higher levels of aggressiveness than that of control flies. CONCLUSION: Visual perception does not play a major role in social suppression of aggression in Drosophila. For single-housed individuals lacking social experience prior to behavioral tests, visual perception decreases the level of aggressiveness.