Sperm Transfer and Utilization by the Arrhenotokous WaspDahlbominus fuscipennis(Zett.) (Hymenoptera: Eulophidae)

Abstract

Abstract>The internal reproductive organs of both sexes are described with regard to their functions during mating and the transfer, storage and use of sperm during oviposition. Although generally hymenopteran in structure they differ in some details from species previously described. The sperm storage organ and glands in the oviducts are more precisely defined and an account given of a structure which regulates the number of sperm entering the sperm bundle prior to its transfer to the female.During copulation thread-like sperm with helical heads are deposited in bundles of 300 in a funnel-like extension of the oviducts produced by a single contraction of the ovaries. Sperm move along the duct to the sperm capsule largely by their own motility. Sperm remain active in the capsule with their heads toward the opening where they are prevented from escaping by a U-shaped loop in the duct. The loop straightens when ova pass through the oviducts, allowing sperm to descend one at a time. Although the precise mechanism by which the storage organ releases sperm is not fully understood, it is unlikely that discontinuity in the release of sperm is the regulating mechanism involved in the production of haploid males in this species.