THE ULTRASTRUCTURE OF DIMORPHIC SPERMATOZOA IN THE HYMENOPTERON DAHLBOMIMS FUSCIPE1SNIS (ZETT.) (EULOPHIDAE)

Abstract

The fine structure of spermatozoa of the arrhenotokous wasp, Dahlbominus fuscipennis (Zett.) was examined by light and electron microscopy with particular reference to a unique dimorphism in the spiralization of the head. Evidence is presented to show that although generally of the "classical" flagellate type, mature spermatozoa are of 2 kinds, 1 with heads that are dextrally coiled and the other with heads that are sinistrally coiled. Both kinds are found in the seminal vesicles of all males and in the spermathecae of all females. The 2 mitochondrial filaments of the tail piece are spirally coiled around the axial filament complex but only in the dextral direction. Sinistral sperm, with opposite gyres in the head and tail piece are thought to be unable to penetrate the egg membranes and thus to be responsible for haploid male production by mated females of this species.