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

cockroaches, we do have anatomical data from the taxonomic
literature from which we can make some inferences.
Here we summarize some of the relevant information
in the hope that it may serve as a springboard for
future investigation.
Female Receptivity
Female cockroaches have strong control of the courtship
and mating process; there are several points in the behavioral
sequence when she can terminate the transaction. In
those cockroach species where females produce volatile
pheromones, she may not call; if males produce the
pheromones, she may not respond. Females may refuse to
mount and feed on the tergites of a displaying male, but
if she does, she may not allow genitalic engagement. If she
does allow genitalic engagement, she may terminate copulation
prematurely. A female’s attractiveness to potential
mates and her response to sexual overtures from them
may or may not be congruent (Brousse-Gaury, 1977).
Males of Su. longipalpa, for example, begin courting females
8 or 9 days after the female’s imaginal molt. Females
of this age do not respond to male sexual displays nor do
they mate. Female calling and sexual receptivity are initiated
11 to 15 days after adult emergence. A lack of calling
behavior in mature females, however, does not necessarily
mean that they are unreceptive; 8% will mate if
courted (Hales and Breed, 1983).
Response to Courtship
In most species newly emerged females require a period
of maturation before they will accept mates. Virgin females
of N. cinerea, R. maderae, and Byr. fumigata become
receptive at an average of 4, 9, and 15 days, respectively
(Roth and Barth, 1964). Eublaberus posticus females
mate just after emergence, after their wings have expanded
but before the cuticle has hardened (Roth,
1968c). Jagrehnia madecassa (Sreng, 1993), Neostylopyga
rhombifolia (Roth and Willis, 1956), and D. punctata
(Roth and Willis, 1955a) females are receptive when they
are freshly emerged, pale, and teneral. The latter have a
narrow window of opportunity for copulation; most that
are isolated for several days following emergence do not
mate when they are eventually exposed to males (Stay and
Roth, 1958). In N. cinerea, younger females require longer
periods of courtship prior to copulation than do older
ones (Moore and Moore, 2001).
Females display their lack of receptivity to courting
males in a variety of ways. A Parc. fulvescens female uninterested
in mating decamps immediately upon contacting
the male (Wendelken and Barth, 1971). Unreceptive
blaberid females commonly flatten themselves against the
substratum with their antennae tucked under their body
(e.g., Byr. fumigata—Barth, 1964). Blaberus females will
lower the pronotum or the entire body (Grillou, 1973),
tilt the body down on the side facing the male, or kick at
courting males (Wendelken and Barth, 1987). Some blattid
females can be aggressively unreceptive, and escalate
their belligerent behavior when courted by highly motivated
males. Occasionally persistence pays off; females
sometimes gradually shift to a less aggressive, more receptive
pattern of behavior (Simon and Barth, 1977b).
Aggression by males directed against unreceptive females
is infrequent. Blaberus giganteus males occasionally bite
an unreceptive female’s wings (Wendelken and Barth,
1987), but forced copulation by males cannot occur in
species where mating is dependent on female mounting
and feeding behavior (Roth and Barth, 1964).
Copulation Refusal
Females often mount and feed on the tergal glands of
courting males, but refuse to allow genitalic engagement.
The nature of tergal secretions may be at least in part responsible;
in the German cockroach the secretions smell
like food and thus may lure hungry females regardless of
their interest in mating. After mounting and feeding, a
cooperative female orients her abdomen and opens her
genital atrium to facilitate interaction with male genitalia
(Roth and Willis, 1952a). Alignment of the two abdominal
tips can require considerable female adjustment, particularly
in species where she is larger than the male. Byrsotria
fumigata females flex the abdominal tip forward
ventrally so that genital connection can be made (Barth,
1964) and Blab. craniifer females may partially dismount
in an attempt to improve the orientation of the genitalia
(Wendelken and Barth, 1987). Cooperative females also
open wide to allow full genital access. In Eur. floridana the
gape of a receptive female’s genital atrium is so impressive
that the male can insert the entire tip of his abdomen
(Barth, 1968b). Species in which the sexes back into each
other also require female cooperation to copulate successfully.
Panesthia cribrata females raise the tip of the abdomen
and open the posterior plates (O’Neill et al., 1987).
After the genitalia are engaged, there are three major
points at which a pair may separate: during turning to the
opposed position, a few seconds after turning, and during
the first 15 min of copulation. The signal to assume
the opposed position comes from the male. He moves
slightly forward, and the female responds by rotating off
his back. If the female initiates the turning, it invariably
results in separation of the pair (Simon and Barth,
1977a). After assuming the opposed position, brief genitalic
connections of 4–7 sec are not uncommon in B. germanica
(Roth and Willis, 1952a). Eublaberus posticus
females frequently kick at the point of intersexual juncture
with their metathoracic legs (Wendelken and Barth,
106 COCKROACHES