In all cockroach species the male transfers sperm to the female via a spermatophore; it begins forming in the male as soon as the mating pair is securely connected (Khalifa, 1950; van Wyk, 1952; Roth, 2003a). When it is complete, the spermatophore in Blattella descends the ejaculatory duct and is pressed by the male's endophallus against the female genital sclerites (Khalifa, 1950). In Periplaneta the spermatophore is not discharged until at least an hour from the beginning of copulation (Gupta, 1947). In N. cinerea, where copulation length is typically short, mating pairs detached after 10-12 min can be separated into three groups. In some, only a copious secretion is present; in others a spermatophore has been transferred but is not secured. A third group has a spermatophore firmly inserted (Roth, 1964b).

Three spermatophore layers can be distinguished in Blattella: a clear, transparent section covering the ventral surface, a lamellated portion that forms the dorsal wall, and at its core, suspended in a milky white mass, are two sacs containing the sperm (Khalifa, 1950). Periplaneta's spermatophore has just one sperm sac (Jaiswal and Naidu, 1976). In Blaberus craniifer the spermatophore consists of four heterogeneous layers, and is invested with a variety of enzymes including proteases, esterases, lipases, and phosphatases (Perriere and Goudey-Perriere, 1988). Several mechanisms exist for fixing the spermatophore in the female (Graves, 1969): (1) the soft outer layer hardens against the female genital sclerites (Blatti-nae); (2) a thick, wax-like shell holds it in place (most Blattellidae); (3) a large quantity of glue-like secretion secures it (Blaberinae, one Zetoborinae); (4) a uniquely shaped, elongated spermatophore is enclosed in a large membranous bursa copulatrix in the female (Diplopteri-nae, Oxyhaloinae, Panchlorinae, Pycnoscelinae, one Ze-toborinae).

When transferring the spermatophore, the male orients its tip so that the openings of the sperm sacs are aligned directly with the female spermathecal pores (Khalifa, 1950; Roth and Willis, 1954b; Gupta and Smith, 1969); this is apparently unusual among insects (Gillott, 2003). The sperm do not migrate from the spermato-phore until copulation is terminated. When first transferred, the spermatophore of N. cinerea contains non-motile, twisted sperm; they became active about 2 hr later. Two to three days after mating only a few sperm remain in the spermatophore but the spermathecae are densely filled with them (Roth, 1964b; Vidlicka and Huckova, 1993). If the spermatophore is removed 25 min after the male and female detach in B. germanica, "a thin thread of spermatozoa, hair-like in appearance, may extend from the female's spermathecal opening" (Roth and Willis, 1952a). It takes about 5 hr for sperm to migrate into the spermathecae of D. punctata (Roth and Stay, 1961). The stimulus for sperm activation may be in male accessory gland secretions transferred along with the sperm (Gillott, 2003), produced by the female in the spermathecae or spermathecal glands (Khalifa, 1950; Roth and Willis, 1954b), or both. Little is known regarding the mechanism by which sperm move from the spermatophore to the spermatheca. Among the nonexclusive hypotheses are the active motility of sperm, migration in chemotactic response to spermathecal or spermathecal gland secretions, contractions of visceral muscles associated with the female genital ducts, and aspiration by pumping movements of the musculature of the spermatheca (Gupta and Smith, 1969). Male accessory gland secretions may play a role in stimulating female muscle contraction (Davey, 1960). The activity and morphology of sperm may change once they reach the spermatheca. In Periplaneta, alterations were noted chiefly in the acrosome (Hughes and Davey, 1969).

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