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

Fig. 9.1 Phylogenetic tree of Dictyoptera, after Deitz et al.
(2003). Mantids branched first, Blattaria is paraphyletic with
respect to the examined Isoptera (Mastotermitidae, Kalotermitidae,
Termopsidae), and Cryptocercidae is the sister group
to termites. The study was conducted utilizing the same morphological
and biological data base used by Thorne and Carpenter
(1992), however, polarity assumptions and uninformative
characters were eliminated, characters, character states,
and scorings were revised, and seven additional characters were
added. The tree suggests a single acquisition of both symbiotic
fat body bacteroids (Blattabacterium) and hindgut flagellates
within the Dictyoptera. Bacteroids were subsequently lost in all
termites but Mastotermes; oxymonadid and hypermastigid
flagellates were lost in the “higher” termites (Termitidae—not
included in tree). The sister group relationship of Cryptocercus
and Mastotermes is supported by phylogenetic analysis of fat
body endosymbionts (Fig. 5.7) and the cladistic analysis of
Klass and Meier (Fig. P.1). *Blattaria denotes Blattaria except
Cryptocercidae.
and Noirot, 1959) that Cryptocercidae is sister group to
termites. It is not, however, a basal cockroach group as
proposed by most early workers (e.g., McKittrick 1964,
Fig. 1). Mantids branched first, with Cryptocercus
Isoptera forming a monophyletic group deeply nested
within the paraphyletic cockroach clade (Fig. 9.1; see also
Fig. P.1 in the Preface and Fig. 5.7). These relationships
are supported by morphological analysis (Klass, 1995),
by analysis of morphological and biological characters
(Deitz et al., 2003; Klass and Meier, 2006), by Lo et al.’s
(2000) analysis of three genes, and by Lo et al.’s (2003a)
analysis of four genes in 17 taxa, the most comprehensive
molecular study to date. The fossil record and the clocklike
behavior of 16S rDNA of fat body endosymbionts in
those lineages possessing them indicate that the radiation
of mantids, termites, and modern cockroaches (i.e., without
ovipositors) occurred during the late Jurassic–early
Cretaceous (Vršanský, 2002; Lo et al., 2003a).
This phylogenetic hypothesis provides a parsimonious
explanation for several key characters of Dictyoptera. An
obligate relationship with Oxymonadida and Hypermastigida
flagellates in the hindgut paunch first occurred
in an ancestor common to Cryptocercus and termites, and
was correlated with subsociality and proctodeal trophallaxis
(Nalepa et al., 2001a). These gut flagellates were subsequently
lost in the more derived Isoptera (Termitidae).
Endosymbiotic bacteroids (Blattabacterium) in the fat
body were acquired by a Blattarian ancestor, or acquired
earlier in the dictyopteran lineage and subsequently lost
in mantids. All termites but Mastotermes subsequently
lost their Blattabacterium endosymbionts (Bandi and
Sacchi, 2000, discussed below). The phylogenetic hypothesis
depicted in Fig. 9.1, then, is consistent with a single
acquisition and a single loss of each of the two categories
of symbiotic associations. Eusociality evolved once, from
a subsocial, Cryptocercus-like ancestor.
Lo (2003) offers two reasons for exercising some caution
in the full acceptance of this phylogenetic hypothesis.
First, for two of the genes that support the sister group
relationship of Cryptocercus and termites, sequences are
unavailable in mantids because they possess neither: 16S
rDNA of bacteroids and those coding for endogenous cellulase.
Second, because cockroach classification is in flux
and taxon sampling is still relatively poor, additional data
may alter tree topology. One possibility is that mantids
may be the sister group of another lineage of cockroaches,
which would render modern cockroaches polyphyletic
with respect to both termites and mantids (Lo, 2003).
Based on their examination of fossil evidence, Vršanský
et al. (2002) suggested that contemporary cockroaches
may be paraphyletic with respect to Mantodea as well as
Isoptera.
The ancestor common to all three dictyopteran taxa
was almost certainly cockroach-like (Nalepa and Bandi,
2000). Cockroaches are the most generalized of the orthopteroid
insects (Tillyard, 1919), while Mantodea are
distinguished by apomorphic characters associated with
their specialized predatory existence. Both cockroaches
and termites have predatory elements in them, although
in termites it is probably limited to conspecifics (i.e., cannibalism).
Mantids have short, straight alimentary canals
(Ramsay, 1990), and like other predators (Moir, 1994),
they neither have nor require gut symbionts. Elements of
certain mantid behaviors are evident among extant cockroaches,
such as the ability to grasp food with the forelegs
(Fig. 9.2), and in some species, assumption of the “mantis
posture” during intraspecific fights. A cockroach combatant
may elevate the front portion of the body, raise the
tegmina to 60 degrees or more above its back, fan the
wings, and lash out with the mandibles and prothoracic
legs (WJB, pers. obs.). Mantids, however, tend to lead
open-air lives (Roy, 1999), and although some are known
to guard egg cases, the suborder as a whole is solitary
(Edmunds and Brunner, 1999). All extant termites, on the
other hand, live in eusocial colonies, and have highly derived
characters related to that lifestyle. There is little
TERMITES AS SOCIAL COCKROACHES 151