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

Polyz. pubescens, Zonioploca medilinea (Blattidae), Neotemnopteryx
fulva, Trogloblattella nullarborensis, and Para.
rufa (Blattellidae). Three are considered accidentals,
two are facultative, and one is an obligate cavernicole
(Richards, 1971). Cockroaches in the family Nocticolidae
are consistent inhabitants of caves throughout the Old
World tropics (Stone, 1988; Deharveng and Bedos, 2000).
Of the approximately 20 species in the widely distributed
genus Nocticola, most are cavericolous, a few are epigean
or termitophilous, and a few can be found both inside and
outside of caves (e.g., Alluaudellina himalayensis) (Roth,
1988; Roth and McGavin, 1994). Juberthie (2000a) estimated
that worldwide, 31 cockroaches species are known
to be obligate cavernicoles, but additional species continue
to be described (e.g., Vidlička et al., 2003). Table 3.3
gives examples of cave cockroaches; others are discussed
in Asahina (1974), Izquierdo et al. (1990), Martin and
Oromi (1987), Martin and Izquierdo (1987), Roth and
Willis (1960), Roth (1980, 1988), Roth and McGavin
(1994), and Roth and Naskrecki (2003).
It is often difficult to label a given species as a cave cockroach
for two reasons. First, many of the described species
are based on few collection records. Second, the term cave
usually refers to an underground space large enough to
accommodate a human, but grand expanses such as these
are just a small part of the subterranean environment
(Ruzicka, 1999). The limits of the hypogean realm are
hard to define because cave habitats grade into those of
the edaphic environment via smaller-scale subterranean
spaces such as animal burrows, tree holes, hollow logs, the
area under rocks, and other such dark, humid, organic
living spaces. Cockroaches found in many of these noncave
habitats occasionally or consistently exploit caves.
Those that are considered “accidentals” are only rarely
collected in caves. Polyz. mitchelli, for example, is a large
ground-dwelling epigean Australian species that has also
been taken in caves (Roach and Rentz, 1998). On the
other hand, those species that typically inhabit cave entrances
may venture outside the cave if the humidity is
high enough (e.g., Para. rufa—Richards, 1971). Among
the cockroaches taken in a range of subterranean-type
habitats is the Asian species Polyphaga aegyptiaca, found
in bat caves, under decaying leaves, and in cliffs along
ravines (Roth and Willis, 1960), and X. immaculata, Eub.
distanti, Blaberus giganteus, Blab. atropos, and Blab. craniifer.
The latter are all considered cave cockroaches, but are
also collected from under decaying litter, in epiphytes, inside
rotting logs, and in the rot holes and hollows of trees,
particularly those that house bats (Darlington, 1970; Fisk,
1977). Perry (1986) described dozens of adult Blab. giganteus
in a tree hollow “all sitting, as sea gulls on a beach,
evenly spaced and facing upward.” Blatta orientalis, Blattella
germanica, and P. americana have all been found in
caves, as well as in buildings, wells, sewers, steam tunnels,
and mines 660 m below the surface (Roth and Willis,
1960; Roth, 1985) (Fig. 3.8). In one sense, however, these
human-made, non-cave habitats may be considered vertebrate
burrows. Cockroaches exhibiting morphological
correlates of cave adaptation such as elongated appendages
and the loss of pigment, eyes, and wings are
generally restricted to cave habitats, but even these can be
found elsewhere. A species of Australian Nocticola with
reduced eyes and tegmina and no wings lives beneath rotting
logs (Stone, 1988). The troglomorphic Symploce micropthalmus
lives in the mesocavernous shallow stratum
of the Canary Islands, but is also found under stones in
humid areas (Izquierdo and Medina, 1992).
Individual caves are commonly divided into zones,
Table 3.3. Examples of cave-dwelling cockroaches.
1. Occur in caves sporadically, and sometimes become established there; show no morphological
characters specifically associated with cave dwelling.
Examples: Blattidae: Periplaneta americana, Polyzosteria mitchelli; Blaberidae: Pycnoscelus indicus,
Pyc. surinamensis, Blaberus colosseus
2. Habitually found in caves, but are able to live in or outside of caves; they show no characters
adaptive for cave dwelling.
Examples: Blattidae: Eumethana cavernicola; Blattellidae: Blattella cavernicola; Blaberidae: Blaberus
craniifer, Eublaberus posticus, Aspiduchus cavernicola
3. Cannot live outside of caves and show marked morphological specializations for the cave habitat
(obligate cavernicoles or troglobites).
Examples: Blattidae: Neostylopyga jambusanensis; Blattellidae: Neotrogloblattella chapmani,
Loboptera anagae, L. troglobia, Paratemnopteryx howarthi, Para. stonei, Trogloblattella chapmani;
Nocticolidae: Alluaudellina cavernicola,Typhloblatta caeca, Nocticola simoni, Noc. australiensis, Noc.
bolivari, Noc. flabella, Spelaeoblatta thamfaranga
52 COCKROACHES