Morphology of the male reproductive tract and spermatozoa of Lasioderma serricorne (Coleoptera: Ptinidae)

Abstract

Xylophagous beetles (Ptinidae) are pests fed on dried and manufactured products from plants or animals. The tobacco weevil, Lasioderma serricorne (Fabricius) (Coleoptera: Ptinidae: Xyletininae) is cosmopolitan, polyphagous and damages stored products, including flour, tobacco and spices. This study describes the morphology of the male reproductive tract and spermatozoa of L. serricorne. The male reproductive tract has a pair of testes with two follicles each, a pair of vasa deferentia and seminal vesicles, five pairs of accessory glands and a single ejaculatory duct opening in the aedeagus. The testis follicles are filled with cysts containing 28 germ cells each. The spermatozoa are spiral and long (1378.6 ± 13.4 μm total length, including 9.2 ± 0.06 μm nucleus) and a tiny acrosome is present. The axoneme microtubular pattern is 9 + 9 + 2, with two symmetrical mitochondrial derivatives and two accessory bodies. The morphologies of the male reproductive tract and spermatozoa of L. serricorne indicate possible adaptations to increase the reproductive success of this beetle, such as mating competition and high population density. This is the first preliminary description of spermatozoa in Xyletininae beetles, which will allow future comparisons with other Coleoptera.