Long-term suppression of courtship behavior in Drosophila melanogaster

Male courtship behavior in Drosophila melanogaster can be modified by experience. Courtship conditioning is an aversive learning paradigm in which female pheromonal cues are associated with a negative courtship experience. Following a one hour pairing with a mated female, a male subject will display suppressed levels of courtship towards virgin female targets for 1 - 2 hours (Siegel & Hall, 1979). A previous study has shown that male subjects will exhibit long-term courtship suppression (up to 7 days) following either a continuous 5 hour pairing with a mated female (massed training) or three spaced 1 hour pairings (McBride et al., 1999), but other studies using similar training protocols have yielded inconsistent results (Nigrini, 1999; Sakai et al., 2004; Presente et al., 2004). Although previously mated females have traditionally been used as unreceptive conditioning targets for courtship conditioning studies, recent studies have found that the use of Tai2 males as conditioning targets can also induce significant courtship suppression that lasts for at least one hour (Cross, 2004). Courtship conditioning Long-Term Memory (LTM) that lasts for at least 3 days is induced following a spaced, but not a massed, training protocol with a Tai2 male. Although it is unclear whether this memory is dependent upon protein synthesis, treatment with a glucose solution immediately following spaced training is sufficient to prevent courtship conditioning LTM. Recent studies suggest that dopaminergic activity is necessary for proper acquisition, but not retrieval of olfactory memory. Although the inactivation of dopamine release does not seem to play a role in the mechanisms that mediate STM of courtship conditioning, this signaling interruption does seem to alter the behavior of naive males towards decapitated targets. These results indicate that courtship conditioning memory is not mediated by the same dopamine-dependent mechanism that underlies memory of aversive olfactory paradigms