Modulation of Drosophila male behavioral choice

Abstract

The reproductive and defensive behaviors that are initiated in response to specific sensory cues can provide insight into how choices are made between different social behaviors. We manipulated both the activity and sex of a subset of neurons and found significant changes in male social behavior. Results from aggression assays indicate that the neuromodulator octopamine (OCT) is necessary for Drosophila males to coordinate sensory cue information presented by a second male and respond with the appropriate behavior: aggression rather than courtship. In competitive male courtship assays, males with no OCT or with low OCT levels do not adapt to changing sensory cues and court both males and females. We identified a small subset of neurons in the suboesophageal ganglion region of the adult male brain that coexpress OCT and male forms of the neural sex determination factor, Fruitless (Fru M ). A single Fru M -positive OCT neuron sends extensive bilateral arborizations to the suboesophageal ganglion, the lateral accessory lobe, and possibly the posterior antennal lobe, suggesting a mechanism for integrating multiple sensory modalities. Furthermore, eliminating the expression of Fru M by transformer expression in OCT/tyramine neurons changes the aggression versus courtship response behavior. These results provide insight into how complex social behaviors are coordinated in the nervous system and suggest a role for neuromodulators in the functioning of male-specific circuitry relating to behavioral choice.aggression ͉ courtship ͉ fruitless ͉ octopamine ͉ sex-specific

Dispensable, Redundant, Complementary, and Cooperative Roles of Dopamine, Octopamine, and Serotonin inDrosophila melanogaster

“…Although neither TH-Gal4 nor Tdc2-Gal4 fully restores courtship to wild-type levels, these data suggest that both DA and OA contribute to important aspects of male sexual behavior. DA has been previously suggested to instigate samesex courtship (Liu et al 2009), female receptivity (Neckameyer 1998b;Wicker-Thomas and Hamann 2008), and male to female courtship behavior (Alekseyenko et al 2010) and OA may modulate the male's choice between courtship and aggression (Certel et al 2007). Similarly, since DA and OA can both rescue male fertility and courtship in the dVMAT mutants, we suggest that they serve complementary or perhaps redundant roles in male sexual behavior (see Discussion.…”

“…Mechanistically, it is possible that DA and OA inputs converge upon a similar common pathway or stimulate courtship via distinct pathways. Although both DA and OA have been implicated in male courtship (Neckameyer 1998b;Certel et al 2007;Alekseyenko et al 2010), the notion that they might serve redundant roles would have been less obvious in previous studies in which only one of these system was disrupted at any one time.…”

“…Overexpression or elimination of one aminergic system at a time has also demonstrated possible dopaminergic effects on courtship conditioning, a learned behavior (Neckameyer 1998a), and on aberrant male-male courtship (Liu et al 2008). One recent report has demonstrated that standard male-female courtship is decreased when DA cells are silenced (Alekseyenko et al 2010) and OA has been shown to modulate the male's choice between courtship and aggressive behaviors (Certel et al 2007). Using genetic rescue of individual aminergic systems in the dVMAT mutant, we demonstrate a role for both DA and OA in normal male sexual activity.…”

A common genetic target for environmental and heritable influences on aggressiveness in Drosophila

“…Recent studies have implicated serotonin, octopamine, and neuropeptide F in the control of aggressiveness in Drosophila. Genes related to these neuromodulatory pathways were not among those identified in our screen (18,(32)(33)(34).…”

A map of octopaminergic neurons in the Drosophila brain

“…are few studies on the architecture and behavioral function of individual octopaminergic neurons in the CNS (e.g., Certel et al, 2007;Zhou and Rao, 2008). A notable exception is VUMmx1, one of the ventral unpaired median (VUM) neurons, in the honeybee.…”