Pest control in the urban environment
Strategies focus on biological methods
By Joanne Littlefield
Pest management usually brings to mind cans of chemical sprays or striped tents draped over buildings. Yet, by understanding more about an insects life cycle; where it lives, what it eats, when and how it reproduces, entomologists can also understand the best ways to manage it when it gets out of control.
This can lead to more environmentally friendly ways of controlling pests, but both the public and pest control professionals need to be taught how to use these new methods.
Teaching certified pest control operators different ways to reduce
pesticide sprays while keeping bug populations in check is one of Dawn
Gouges main goals. As a research entomologist with the University
of Arizonas Department of Entomology in the College of Agricultural
and Life Sciences (CALS), she is focusing on Integrated Pest Management
(IPM), a pest management strategy that provides long-term management
of pest problems with minimum impact on human health, the environment
and non-target organisms. Her studies in mosquito, termite and cockroach
control are yielding results that are changing the way people fight
According to Gouge, the management of urban mosquito populations using
novel organic acids could lead to alternatives to costly chemical sprays.
Her mosquito research is an applied project using organic acids to reduce
turf compaction on school grounds, increasing drainage and eliminating
mosquito breeding reservoirs (see sidebar for pest management program
I consider the mosquito research we are conducting to be of most
importance, Gouge says. Optimizing management of bugs that
compromise human health is our highest priority.
Arizona termite species thrive in dry, hot weather. When they become
established in an area the damage they do often poses serious structural
problems that can halt construction and delay home sales. Current control
methods might include wrapping the entire home in a circus-like tent
and inundating the home with a pesticidal fumigant, or a pre-treatment
consisting of digging narrow trenches along walls and drilling through
horizontal surfaces and into voids, applying materials where they will
kill termites within the home and block the colonys re-entry.
Entomologists based at the UAs Maricopa Agricultural Center in
central Arizona are studying alternative methods of eliminating termite
colonies. Gouge is investigating the use of biological pest control
agents, in this case, worms from the nematode genera Steinernema and
Heterorhabditis. These tiny worms, called entomopathogenic nematodes,
are placed in the soil of a termite colony. When eaten by the termite,
they go to work breaking down the termites body using digestive
enzymes and toxins.
It is not known for sure if nematodes are able to penetrate directly
through the cuticle (hard outer coating) of termites or ants,
Gouge says. The insects do definitely ingest them, but it is likely
that nematodes in the genus Heterorhabditis are also capable of entering
the insects body directly, since they have a terminal tooth and
have been photographed entering other insect species directly through
A possible disadvantage is that Gouge says termites have been documented
conducting certain behavioral activities which could minimize nematode/termite
contact. Termites can detect an individual which has become infected
and will remove it from the nest, or wall that termite up in a remote
part of the colony. Both ants and termites groom themselves furiously
when the nematodes crawl over them, Gouge says.
This research is just one of the projects Gouge is conducting. By assessing
the potential use of various microbial species as bioinsecticidal agents,
she says there can often be a decrease in the use of pesticides sprayed
throughout the environment.
Compared to other parts of the country, urban areas in the Sonoran
Desert may have a different spectrum of insect pests. But once these
non-native populations become established they can cause economic as
well as health concerns to humans. An insect pest new to Arizona is
the Turkestan cockroach (Blatta lateralis). The Turkestan cockroach
was first found in the United States at a military supply center on
the West coast, and has migrated to arid regions of Texas, New Mexico
This medium-sized cockroach was discovered in Phoenix during inspections
for a school IPM program, in sticky traps placed in the school buildings.
Because it was believed to live primarily outdoors, its discovery led
researchers on a hunt to see how and why they were coming indoors. Cockroaches
will eat almost anything but are especially fond of starchy materials
such as cereals, sweetened or sugary substances, and meat products.
Many areas in schools offer the perfect habitat for pest insects.
Not much research has been done on the Turkestan cockroach in the urban areas of the Sonoran Desert, so Gouge and her colleagues have captured live specimens to observe in the lab. Once trained to look for them, school maintenance personnel have been able to take the necessary steps in pest proofing the buildings. Taking a close look at reducing the cockroachs habitat allows for an alternative to monthly spray regimes, according to Gouge.
Education Makes The Difference
Gouge says while IPM is fairly well understood by agricultural producers, making it work in the urban environment sometimes requires re-education in pest management strategies for homeowners, pest control operators, and other people who routinely deal with pest control. IPM programs are educationally basedthey focus on knowing pest biology, habits and habitats, Gouge says. A quick check of the yellow pages in any community will show listings for many pest control operators. Educating them in new management methods could make the difference in helping them stay in business while offering safer alternatives to potentially harmful chemical residue.