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Association
of Zoological Horticulture Newsletter April 2000
This article
makes recommendations based upon a successful German cockroach control
program implemented by the author in a commercial animal housing facility.
Using an Integrated Pest Management (IPM) approach the situation has been
brought under control and the roach population is being maintained at
acceptable levels.
The problems
in this facility were caused by the excessive use of organophosphate insecticides
for roach control over a period of several decades. As a result the facility
had developed an overwhelming population of an insecticide resistant strain(s)
of German cockroaches. Poor housekeeping had exacerbated the problem.
Because of the author's successful experience with horticultural IPM programs
(Shimonski 1991), a similar approach was taken with the roach control
program. A program that stressed a minimal use of insecticides and limited
as much as possible the exposure of animals, humans, and the environment
to those insecticides was established.
A more common
sense approach to housekeeping (in the animal facility) as well as habitat
reduction for the roach population was also undertaken. The consequences
of the excessive use of insecticides is summed up in a document published
by The Ohio State University Entomology Extension: "To date, only
the German Roach has developed a degree of resistance that presents control
problems. There is a natural evolutionary process accelerated by intense
selection pressure created through the use of insecticides. (The more
insecticide applied the greater the selection for resistance.) Never increase
dosages. For example, by killing off susceptible roaches, there remains
an untouched resistant roach that becomes a larger segment of the remaining
population. As a result, insecticides that at one time controlled a largely
susceptible population are no longer effective against the remaining altered
population and most of its descendants."
Another important
factor in resistance management is the rotation of insecticide classes
(Cochran 1990). The author's IPM program was based upon the use of unrelated
insecticides of different chemical classes and modes of entry into the
insect. It is important to attack insects at different points in their
body in order to overwhelm their defense systems. These chemicals should
be used in a sequential treatment pattern. A typical IPM program might
consist of different chemicals being used on a monthly cycle. For example,
an organophosphate can be used the first month, the second month a carbamate,
the third month boric acid, the forth month insect growth regulators.
Experiments
undertaken in the entomology laboratory at UCLA have shown that the principal
factor affecting the efficacy of an insecticide against roaches is its
repellency (Ebeling date unknown). The greater the repellency of the insecticide,
the greater the chances that a certain percentage of roaches would learn
to avoid treated areas before picking up lethal doses. Some of the organophosphates,
i.e. Dursban and Diazinon, are very repellent. It is prudent to make non-repellent
insecticides, such as boric acid, a major component of an IPM program.
Repellent chemicals such as the Pyrethroids can be used as a "knock-down"
to get the roaches to contact the boric acid.
One of the
major components of an IPM roach control program is sanitation. Good general
housekeeping that prevents roach infestations is as important as any insecticide.
Food and water (and places to hide) must not be available to attract (and
maintain) any of these pests. Ventilation is also an important consideration
from an animal or human point of view.
There are
proteins that have been isolated from roaches that have been proven to
cause human allergies. "A growing body of evidence has implicated
allergens derived from roaches as an important environmental factor that
may aggravate asthma in sensitized persons" (O'Connor and Gold 1999).
The following IPM program was developed by the author to control the roach
infestation in the animal housing facility.
A monitoring
program was put in place to determine the efficacy of the IPM program.
Sticky pheromone traps were placed throughout the buildings where insect
control was to be initiated. The traps were put in place and trapped roaches
were counted once a week before the chemical control began. This allowed
for a baseline of comparison during the program. The traps were to be
monitored on a weekly basis and when full, replaced with new traps. The
use of the monitoring traps enabled "precision targeting" (Weaver
1998).
By indicating
the areas of high insect density where treatment was needed, and low insect
density where little or no treatment was required, the quantity of insecticides
was reduced, the efficiency of the chemicals was increased and the overall
cost of the program was reduced. Housekeeping was improved. Food and water
for the animals was more closely monitored. Dead and dying roaches were
removed each morning and destroyed. This was very important. Often insects
recover after the initial poisoning and will be the precursors to a resistant
strain.
The first
round of insecticide application consisted of a fipronil gel and bait.
An insect growth regulator was also applied. One week after this application
approximately 99% of the roaches had been killed. The low population count
of roaches lasted about five weeks. An increase was noted by workers in
the facility and the monitoring traps confirmed this change.
The second
round was then initiated. A boric acid product was dusted in the areas
where the roaches were noticed. This precision targeting had excellent
results, with roach numbers being reduced once again to the low levels
obtained after the first treatment. After eight months this IPM roach
control program has been very successful. Since the boric acid application,
only a handful of roaches have been found. The ultimate reduction of the
German roaches to a manageable level on a permanent basis appears to be
possible using the precision targeting method and a more holistic approach
to insect control. Obviously some of the other insecticides such as the
organophosphates or the carbamates may be used in the future but their
use should be minimal and only occasional.
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Citations:
Cochran, D.G. 1990, Managing resistance in the German Cockroach.
Pest Control
Technology 18(2):56-57 Lyon, William F.
German Cockroach:
HYG-2099-97, Ohio State University Extension, Entomology Fact Sheet O'Connor,
George T. and Gold, Diane R. 1999,
Cockroach
Allergy and Asthma in a 30-Year-Old Man, Grand Rounds in Environmental
Medicine, Environmental Health Perspectives, 107(3)
March 1999
Shimonski, J. (1991), An Integrated Pest Management Plan for the Control
of Phytophagous Mites (Tetranychidae) on Musoid Plants
(Scitaminae). Heliconia Society Int. Bulletin. Vol. 5, No. 2
Walter Ebeling,
Pests On or Near Food, Urban Entomology Chapter 6,
University
of California, Riverside Entomology website: http://entmuseum9.ucr.edu/ent133/ebeling/ebeling6.html
Weaver, T.
(1998), Curbing Cockroaches and their Allergens.
Agricultural Research Magazine, Vol. 46, No. 6
Jeff Shimonski
Parrot Jungle and Gardens January 13, 2000 |
