Mating Behaviour and Copulatory Mechanism in the Scorpionfly Neopanorpa longiprocessa (Mecoptera: Panorpidae)

Sexual conflict during copulation may drive morphological and behavioral evolution in insects. Although nuptial feeding behaviour is well studied in Panorpa, whether this behaviour is universal in Panorpidae remains unknown. The scorpionfly Neopanorpa longiprocessa Hua & Chou, 1997 was investigated for its mating behaviour, functional morphology of the notal organ, and external genitalia using light microscopy and scanning electron microscopy. The results show that the mating behaviour is not associated with nuptial feeding in N. longiprocessa. The morphological basis of this non-nuptial copulation is likely related to the developed notal organ of the male. The notal organ serves a function to seize wings of the female during copulation. Only males that succeed in seizing the female with the notal organ are able to establish genital contact and copulate. The male genitalia exhibit distinct species-specific modification. The epandrium (tergum IX) has evolved a pair of ventral bulbs to grasp the subgenital plate of the female. The hypandrium (sternum IX) has a pair of dorsal processes to control the abdominal end of the female. These results indicate that nuptial feeding is not a universal behaviour in Panorpidae. Presumably, these grasping apparatuses compensate the scorpionflies that fail to provide nuptial gifts, as exemplified by N. longiprocessa.