The structure, formation, histochemistry, fate, and functions of the spermatophore of Lytta nuttalli Say (Coleoptera: Meloidae)

Abstract

The spermatophore of Lytta nuttalli consists of a unique tubular structure and a mass of jelly-like material (JLM). The spermatozoa are located in the JLM at its junction with the tube. The tube wall is composed of three layers of "histochemically" different substances produced by the first pair of male accessory glands. The JLM is secreted by the vasa deferentia. During copulation, usually of 8 to 10 h duration, the tube is molded and hardened in the vagina and posterior part of the spermatophoral receptacle duct and the JLM in the anterior part of the duct. The tube of the spermatophore serves as an intromittent "organ" in the absence of an internal penial sac. The sequence of events in spermatophore formation and the roles of the materials from the second and third pairs of male accessory glands are described. After copulation, usually within 2 h, the tube is ejected by the female. Within 24 h after copulation, most of the spermatozoa are transferred to the spermatheca. The secretion of the female accessory gland apparently is involved in this process. The JLM and third male accessory gland materials are retained in the spermatophoral receptacle and apparently are absorbed. The histochemical composition of the male and female secretions and the components of the spermatophore and the cytology and secretory cycles of the glands are described. The spermatophore of L. nuttalli is compared with those of other insects and the probable form of the spermatophore in other Meloidae is considered.