Cockroache; Ecology, behavior & history - W.J. Bell

stimulation via mechanoreceptors that are abundant
within the brood sac (Brousse-Gaury, 1971a, 1971b;
Roth, 1973b; Greenberg and Stay, 1974). Internal gestation
of eggs, then, leads to potentially large differences
between oviparous and ovoviviparous species in the sexual
availability of females (Wendelken and Barth, 1987).
Live-bearing females are removed from the mating pool
for extended periods of time; gestation lasts 35–50 days
in N. cinerea (Roth, 1964a), 51 days in R. maderae (Roth,
1964b), and 55–65 days in Blab. craniifer (Grillou, 1973).
Blattella germanica, a species that externally carries the
ootheca for about 21 days before the young hatch (Roth
and Stay, 1962c), is intermediate. Oviparous females that
drop their oothecae shortly after their formation lack the
lengthy gestation periods of ovoviviparous cockroaches
(Chapter 7) and so have relatively high rates of “recidivist
receptivity” (Wendelken and Barth, 1987). Potentially,
then, these females mate more frequently and presumably
with a greater number of males.
Secondary Effects of Copulation
The primary role of copulation is egg fertilization, but a
variety of secondary effects also occur. In cockroaches
these include the suppression of female receptivity, but
also diverse processes that facilitate female reproduction,
such as the acceleration of oocyte growth, the prevention
of oocyte degeneration, an increase in the number of
oocytes matured and oviposited, the appropriate construction
of the egg case, and, in ovoviviparous species, its
proper retraction. The degree to which mating influences
these processes as well as the details of their physiological
control vary among studied species (Griffiths and Tauber,
1942a; Wharton and Wharton, 1957; Roth and Stay, 1961,
1962a, 1962c; Engelmann, 1970; Roth, 1970b; Adiyodi
and Adiyodi, 1974; Hales and Breed, 1983; Goudey-Perriere
et al., 1989). These secondary effects clearly promote
female reproductive fitness, but are also considered
beneficial to the male because they increase the likelihood
that his sperm will be used by the female to sire her eggs
(reviewed by Cordero, 1995; Gillott, 2003).
Mating has been shown to stimulate oocyte maturation
in all cockroach species studied to date (Holbrook et
al., 2000b), but the instigating stimuli differ. The physical
presence of the spermatophore, stimulation from male
genitalia, mechanical pressure from a filled spermatheca,
and the chemical presence of the spermatophore all have
varying degrees of influence on female reproductive
processes. The action of these stimuli also may be moderated,
sometimes strongly, by nutritional and social factors.
The mechanical stimulation caused by the firm insertion
of the spermatophore in N. cinerea not only
suppresses female receptivity, but is also responsible for
stimulating oocyte development and for ensuring the
normal formation and retraction of the ootheca during
the first reproductive cycle (Roth, 1964b). The physical
presence of the spermatophore has been similarly
demonstrated to be sufficient stimulus for accelerating
oocyte maturation in oviparous Su. longipalpa; an artificial
spermatophore is a reasonable substitute (Schal et
al., 1997). Diploptera punctata females are dependent on
spermatophore insertion for rapid development of their
oocytes. However, the act of mating alone, without passage
of a spermatophore, may be sufficient for oocyte
maturation in some females. The physical stimulus of the
spermatophore together with the action of the male genitalia
appear to produce maximum reproductive effects
(Roth and Stay, 1961). The acceleration of oocyte growth
that occurs after mating in P. americana can be prevented
by removing the spermatophore prior to the movement
of sperm into the spermatheca, or by mating the female
to males whose spermatophores are of normal size and
shape but lack sperm. Pipa (1985) concluded that the
stimulus for oocyte growth in this species originates from
the deposition of sperm or other seminal products into
the spermatheca. The proper formation and retraction
of the ootheca into the brood sac in N. cinerea (Roth,
1964b) and Pyc. indicus is dependent on the presence of
sperm in the spermatheca. After spermatheca removal,
severance of spermathecal nerves, or mating with castrated
males, females produced abnormal egg cases or
scattered the eggs about (Stay and Gelperin, 1966).
Male accessory glands typically contain a variety of
bioactive molecules that, when transferred to the female
during mating, influence her reproductive processes
(Gillott, 2003). The spermatophore of Blab. craniifer is
richly invested with enzymes whose activities change during
the three days subsequent to mating; the longer the
spermatophore remains in place (from 0–24 hr), the
sooner oviposition occurs. Acetone extracts of the spermatophore
topically applied to the female induce the
same increases in vitellogenesis as do juvenile hormone
mimics. Nonetheless, the physical presence of the spermatophore
is also required for the full expression of reproductive
benefits, and both mechanoreceptors and
chemoreceptors are found in the bursa (Brousse-Gaury
and Goudey-Perriere, 1983; Perriere and Goudey-Perriere,
1988; Goudey-Perriere et al., 1989).
In many cockroach species the female either internally
digests and incorporates, or removes and ingests the spermatophore
sometime after it is transferred to her (Engelmann,
1970). However, there is currently little evidence
that spermatophores are of nutritional value, aside from
the uric acid that covers them in some species. Mullins et
al. (1992) injected 3 H leucine into male B. germanica. The
males transferred it to females during mating, who sub-
110 COCKROACHES