Study of the reproductive system and ovarian development of Dioryctria rubella Hampson

[Objectives] To investigate and describe the morphology of the reproductive system and ovarian development in Dioryctria rubella, and deduce the parts of the male and female genitals involved copulation based on their structural characteristics, with the goal of providing a basis for further study of the reproductive biology and sex pheromones of this insect. [Methods] The characteristics of the internal and external reproductive organs, and female ovarian development, were investigated by dissection and scanning electron microscopy. [Results] Compared with the reproductive systems of other Phycitinae species, distinctive structural characteristics of the reproductive system of D. rubella were as follows:(1) the corpus bursae possessed a well-developed signum, the seminal duct arises from the ventral surface of the corpus bursae, and no bulla seminalis was found.(2) The female sex pheromone gland was ring-like and situated in the intersegmental membrane between the 8th and 9th abdominal segments. Adult males possess well-developed scale brushes, which consist of six pairs of overlapped accessories.(3) The spines on the inner surface of the ductus bursae and the cervix bursa were complementary in position and direction, and a close match, to those of the cornuti on the outer surface of vesica. Furthermore, ovarian development could be divided into 5 stages; the ovaries of 2 day old females were well-developed but began to degenerate after females reached 4 days of age. [Conclusion](1) The well-developed male scale brushes and highly matched genitals are indicative of complex courtship and mating behavior. The lifetime of adults is so short that they may only mate once.(2) Ovarian development is almost complete after female emergence, which indicates that post-emergence nutrition may not be a decisive factor in ovarian development.