Androconial Scales and the Sex Pheromone of the Danaini Male Wing: Secretory Cells in the Adult Wing

Among lepidopterans whose mating behaviors involve sex pheromones, the female sex pheromone emitted from the gland located at the female abdominal tip has been mainly reported. In some lepidopterans, however, male wings contain sex pheromones, and they have morphologically specialized androconial scales as well as common scales. This chapter addresses the sex pheromone and androconial scale, called the cushion scale, in the male wing of danaine butterflies (Nymphalidae), mainly those of Parantica sita and Amauris ochlea. Their significant features are as follows. (i) The cushion scales are distributed in the small region, called the sex brand or the alar organ, of the hind wing. The cushion and common scales are linearly and alternately arranged in this region. (ii) The danaine male ingests the raw materials for the sex pheromone during its adult stage. The living cells underneath the cushion produce the sex pheromone. (iii) The androconial scale is easily detached from the cushion surface, and small pores are produced in the cushion surface after scale detachment. (iv) Through the contact between the abdominal tip and the sex brand, the sex pheromone stored in the living cells flows out through the cushion pore and is subsequently transferred to the hairpencils of the abdominal tip. (v) The sex pheromones accumulated in hairpencils are emitted to females during mating. Many of these features are fairly different from those of Pieris butterflies (Pieridae), which is addressed in Chap. 3 . The production, storage, and emission of volatile compounds in the male wings of Danaini and Pieris are comparatively discussed.