In primitively-eusocial hymenopterans that lack morphological castes, the formation of dominance hierarchy and the determination of reproductive/helper roles are essential to the eusosial colony organization. In the queenless monogynous ant genus Diacamma, the polyethism of monomorphic females accounts for the differentiation of reproductives and helpers. Such polyethism without morphological castes allows us to study molecular basis for the reproductive division of labor.
 In the genus Diacamma, behavioral ontogeny is controlled by an unique process, the social mutilation of Diacamma-specific vestigial wings, called “gemmae”. While the females whose gemmae are mutilated by their colony members immediately become “timid” and differentiate into workers, only one female with intact gemmae mates and becomes a gamergate (Fukumoto Y et.al. 1989, Physiol.Ecol.Japan 26,55-61, Peeters and Higashi 1989, Naturwiss. 76,177-180).    
 As a first step to elucidate the molecular basis of behavioral modulation, the process of behavioral and physiological differentiation was described in detail. For the first few days after eclosion, the future gamergate, i.e. an unmated female with gemmae, showed aggression towards colony members. After a week, the aggression was depressed and her ovaries gradually developed. Considering that an Indian species D. ceylonens also shows similar behavioral change (Cuvillier-Hot et.al. 2002, Proc.R.Lond. 269,1295-1300), the decrease of the aggressiveness is common in the genus Diacamma, but the acquisition of the highest rank is attained in shorter period in the Japanese Diacamma than D. ceylonens that requires 30 days for the depression of aggressiveness.
 To analyze the molecular basis of neuroethological changes accompanied with the reproductive division of labor, we compared the mRNA from the female heads of 4 behavioral categories (1day aggressive future gamergate(FG), 7day aggressiveness-depressed FG, and 1 and 7 day worker), using fluorescent differential-display method. We here report the detailed processes of behavioral ontogeny and current results on the differential-display in Diacamma.