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

lattellids, from his 0.65 ha of rainforest in Kuranda,
Queensland (elev. 335 m asl). In one light trap study in
Panama, 42% of 164 species captured were new to science
(Wolda et al., 1983).
NEGATIVE IMPACT OF COCKROACHES
Fig. 10.5 Li Li, Chinese Academy of Science, Kunming, and
Wang De-Ming, Forest Bureau, Diqing Prefecture, opening a
rotted log containing Cryptocercus primarius in a young regrowth
spruce and fir forest at Napa Hai, Zhongdian Co., Yunnan
Province, China. The cockroaches were found in large logs
left on the forest floor after the forest was harvested; maximum
regrowth was 10 cm in diameter. This site was immediately adjacent
to a mature coniferous forest with logs also harboring
the cockroach. Photo by C.A. Nalepa.
The insects showed no significant response to habitat
fragmentation and livestock activity, but were most diverse
where forest litter was thickest. The authors explain
their results in terms of the fire ecology of the area. In seasonally
dry habitats cockroaches appear to have a high degree
of tolerance to recurrent disturbances and may aestivate
in burrows or under bark during harsh conditions
(Abenserg-Traun et al., 1996b; Abbott et al., 2003). There
is a distinction, however, between cockroaches adapted to
these habitats and those residing where the ecological
equilibrium is much more precarious. Tropical rainforests,
where the vast majority of cockroaches live, are
under heavy assault (Wilson, 2003), and large numbers of
described and undescribed species are being lost along
with the natural greenhouses in which they dwell. Grandcolas,
for example, estimated 181 cockroach species in a
lowland tropical forest in French Guiana, with 67 species
active in the understory during night surveys in one site
(Grandcolas, 1991, 1994b). David Rentz (pers. comm. to
CAN) has recorded 62 species of cockroaches, mostly
The negative impact of cockroaches introduced into
non-native habitats is well documented. The handful of
species that have invaded the man-made environment
have had enormous economic significance as pests, as
sources of allergens, as potential vectors of disease to humans
and their animals, and as intermediate hosts for
some parasites, such as chicken eye-worms. Exotic cockroaches
have also been introduced into natural non-native
ecosystems like caves (Samways, 1994) and islands,
such as the Galapagos (Hebard, 1920b). In a survey of La
Réunion and Mayotte in the Comoro Islands, 21 cockroach
species were found, with introduced species more
common than endemic species that use the same habitats.
The abundant leaf litter and loose substrate typical of
cultivated land was favorable habitat for the adventive
species, particularly in irrigated plots (Boyer and Rivault,
2003). The Hawaiian Islands have no native cockroaches,
but 19 introduced species (Nishida, 1992). Periplaneta
americana has invaded a number of Hawaiian caves, and
is thought to have contributed to the decline of the Kauai
cave wolf spider (Adelocosa anops) by affecting its chief
food source, cave amphipods. The cockroach opportunistically
preys on immature stages of the amphipods,
and competes with older stages at food sources (Clark,
1999). In Florida, laboratory studies indicate that the
Asian cockroach Blattella asahinai may disrupt efforts to
control pest aphids with parasitic wasps by feeding on
parasitized aphid “mummies” (Persad and Hoy, 2004).
Although this problem occurred primarily when the
cockroaches were deprived of food for 24 hr, the high
populations of Asian cockroaches that can occur in citrus
orchards (up to 100,000/ha) (Brenner et al., 1988) guarantee
that some are usually hungry.
OUTLOOK
The meager information we currently have on cockroach
activities in natural habitats suggests that they may be key
agents of nutrient recycling in at least some desert, cave,
and forest habitats. They comprise the core diet for a variety
of invertebrate and vertebrate taxa, and may play
some role in pollination ecology, particularly in tropical
canopies. Before we can begin to document and quantify
their ecosystem services, however, more time, energy, and
financial resources must be devoted to two specific areas
of cockroach research.
174 COCKROACHES