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

Table 7.1. Modes of reproduction in cockroaches. After Roth (1989a, 2003c).
Characters Oviparity A Oviparity B Ovoviviparity A 1 Ovoviviparity B 2 Viviparity 3
Handling of ootheca Dropped shortly after Carried externally After it is formed, No ootheca; eggs After it is formed,
formation throughout gestation retracted into the pass directly into retracted into
brood sac brood sac the brood sac
Physical properties Hard and dark, Proximal end is In most, variably — Incomplete
of egg case completely enclosing permeable reduced and membrane
eggs
incomplete
Water handling Sufficient water in Obtains water from Obtains water from Obtains water from Obtains water
eggs, or additional the female during the female during the female during from the female
water absorbed from embryogenesis embryogenesis embryogenesis during embryosubstrate
genesis
Pre-partition non- No Water-soluble Probably water- Probably water- Proteinaceous
yolk nutrients from material soluble material soluble material secretion from
mother?
walls of brood
sac
Taxa All but Blaberidae A few Blattellidae A few Blattellidae, One tribe of Bla- One known speand
some Blattel- most Blaberidae beridae (Geosca- cies of Blaberilidae
pheini) dae
Examples Periplaneta, Blattella, Blaberus, Macropanesthia, Diploptera
Eurycotis Lophoblatta Nauphoeta Geoscapheus punctata
1
”False” ovoviviparity of earlier studies.
2
”True” ovoviviparity.
3
”False” viviparity.
crest, the keel, runs along the mid-dorsal line of the egg
case, and at hatch, the nymphs swallow air, forcing open
this line of weakness (as in the opening of a handbag).
The hatchlings generally exit en masse, and the keel snaps
shut behind them (Fig. 7.1). If some eggs are lost due to
unviability, parasitism, or disease, the entire brood may
fail to hatch, because opening the keel typically requires a
group effort. The ootheca is structurally sophisticated
(Lawson, 1951; D.E. Mullins and J. Mullins, pers. comm.
to CAN), and functions in gas exchange, water balance,
and mechanical protection.
The oothecae of oviparous type A cockroaches vary in
their ability to prevent water loss from the eggs (Roth and
Willis, 1955c). In some species the ootheca and eggs at
oviposition do not contain sufficient moisture for embryogenesis;
in these the ootheca must be deposited in a
humid or moist environment where the eggs absorb water
(e.g., Ectobius pallidus, Parcoblatta virginica). Alternatively,
if the ootheca and eggs contain sufficient moisture
for the needs of the embryos at the time of oviposition,
the ootheca possesses a protective layer that retards water
loss (e.g., Blatta orientalis, Periplaneta americana, Supella
longipalpa). The eggs of Blatta orientalis hatch even if
oothecae are kept at 0% relative humidity during development.
When physically abraded, however, the oothecae
lose 60% or more of their water within 10 days, while controls
lose only 5% (Roth and Willis, 1955c, 1958a).
Oothecal Deposition and Concealment
Fig. 7.1 Unidentified neonate cockroaches freshly hatched
from an ootheca attached to a leaf, Bukit Timah, Malaysia. Note
that the keel has snapped shut behind them. Photo courtesy of
Edward S. Ross.
The majority of oviparous type A cockroaches select and
prepare a site for egg case deposition with some care
(Chapter 9; Roth and Willis, 1960; Roth, 1991a), and the
stereotyped behavioral sequences involved have been
used as taxonomic characters (McKittrick, 1964). Therea
petiveriana simply deposits oothecae randomly in dry
leaves (Ananthasubramanian and Ananthakrishnan, 1959).
Other species attach them to the substrate (with saliva or
genital secretions), and many find or construct a crevice,
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