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

Fig 7.10 Post-oviposition provisioning in cockroaches. Oviposition refers to the release of eggs from
the ovaries, while extrusion is the permanent expulsion of eggs from the body. Deposition is the disassociation
of the egg case from the body. Independence is the ability of neonates to live apart from
the parent(s). Modified from Nalepa and Bell (1997), with the permission of Cambridge University
Press.
Perisphaerus sp. and Thorax porcellana both exhibit a reduction
in the number of offspring per clutch as compared
to other ovoviviparous species (Roth, 1981b).
PARENTAL INVESTMENT
In the majority of oviparous type A cockroaches females
make their principal direct investment prior to fertilization,
by supplying eggs with yolk nutrients. They then envelope
the eggs in a protective covering and deposit them
in a safe place for incubation. With the exception of Cryptocercus,
there is no additional parental involvement. In
species with external retention, like Blattella, embryos are
dependent on yolk to fuel development but are also progressively
supplied with water and some non-yolk nutrients
during gestation (Fig. 7.10). This is likewise true of
ovoviviparous cockroaches, but in several species neonates
continue their dependence on maternally supplied
nutrients for a period of time after hatch. These take the
form of digestive fluids and glandular secretions; at least
six types are known (Chapter 8). Cockroaches tend to
have a very glandular integument, allowing for the repeated
evolution of nutritive secretions from cuticular
surfaces. Williford et al. (2004) recently demonstrated
that proteins in the milk secreted by the brood sac of
Diploptera are coded by genes from the same family
(lipocalin) as those that code for a protein in the tergal
gland secretion of R. maderae (Korchi et al., 1999).
REPRODUCTION 129