What makes the
cockroach a good lab animal?
Criteria for a good laboratory animal:
Is the organism easy to rear?
Cockroaches are easy to raise in the lab. The only problem
is containing their growth. A large number of species can be maintained
in laboratory cultures. Three pest species have been raised routinely
in synchronous culture: Blattella germanica,
and Blatta orientalis. Of 32
species which have been raised
by this worker in laboratory cultures, 18 species were able to be cultured
synchronously, Table I (Kunkel, unpublished).
Can the organism be stored at any stage?
Cockroaches can be stored at 15°C for extended periods of time (months
with some additional care) in a state
of suspended animation.
When they are needed for experimental use they can be placed in a warmer
incubator and given food and water.
Is its size convenient?
Cockroaches of several convenient sizes are available. For
a small cockroach, Blattella germanica is a preferred species (60
mg unfed adult female) with substantial historical interest in its biology,
physiology, development and control. For a mid-sized cockroach, The
Cockroach, Periplaneta americana is a good choice (850 mg unfed
adult female) with unequaled historical interest in its biology and physiology.
For a large sized cockroach either Gromphadorhina portentosa or
Blaberus giganteus will each provide several grams of adult tissue
from each adult female.
Is it inexpensive to rear?
The cost of rearing of cockroaches can vary tremendously depending on what
species, quality and quantity of animals are required and how much effort
is able to be devoted to the rearing process. For minimal cost, mass
cultures are possible which are started in large containers (i.e. garbage
containers) and the only interaction with the colony involves providing food
and water and preventing escapees. Colonies of this type grow and mature and
accumulate wastes which eventually limit space.
of the above mass cultures can be formed by sorting individuals
into size classes. Some synchrony can be obtained in these cultures by
controling food availability.
The added cost of this approach includes space
for the subcultures and personnel time in sorting and separate rearing.
The most expensive in time and effort involves maintaining strictly
synchronous cultures. These are the highest quality lab animals used for
demanding research objectives
). With modest resources [7 hours per week animal
care; one refrigerated incubator (15°C) and one heated incubator
a house or water aspirator or rotary vane suction pump] a high quality
research animal facility can provide up to 2000 synchronous adult females
per month. Additional efficiencies can be obtained by scaling up the operation
to larger numbers and sustained use of the facility. A sustained production
of approximately 2000 synchronous adult female Blattella germanica
per month was maintained over a 5 year period at a unit cost of about $0.66
per adult female including personnel, equipment and facility costs. This also
included a wastage of all the males which were not used in the study.
Does it have a short life cycle?
The turn around time for the smallest laboratory
cockroach, B. germanica, is 3 months
(~93 days egg-hatch to egg-hatch)
allowing 4 generations
per year. Larger cockroaches have similarly longer life cycles.
Is it genetically manipulable?
The German cockroach B. germanica has been studied extensively as
a genetic organism (Ross,
1966-1993). Twelve linkage groups have
been identified and many linkage groups have been linked with chromosomes
via translocation mutants.
Is it economically important?
Cockroaches form a group which are only rivaled by the mosquito
in economic and health consequences in the western world. As a pest
the cockroach is unrivaled as an urban pest. There is a zero tolerance
of cockroaches in the minds of most housekeepers and restaurateurs.
As a threat to health, its prior importance was minimized due to its low
vagility (ability for individuals to travel during their lifetime) but
recently its importance as a contributor of allergens promoting childhood asthma
has boosted interest in its control.
Dose it have an audience of interested people?
Interest in the cockroach has been shown by the pesticide industry,
the medical community, neurobiologists, developmental biologists and a
fascinated public. It seems for many prominent newspapers (including the NY
Times) an article on cockroaches is obligatory at least once a year either as a newsworthy item
or as a human interest story.
Interactions between criteria?
The ability of several laboratory species to be cultured synchronously
provides a lab animal perfect for studies where the developmental age is
critical. It can also provide a more uniform test organism for development
of targeted pesticides which function by attacking a particularly vulnerable
stage of life.
last updated by JG Kunkel 6/1/97.