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4
Pest Management
Pests, including insects, rodents, nuisance birds, and certain mammals, are common in zoos because of the
ready availability of shelter, food, and water. Control of pests is a critical aspect of preventive medicine at
zoological parks (AAZV, 1999). Pests are vectors or reservoirs of disease that can adversely affect zoo animals.
Pests can also significantly degrade the aesthetic quality of the park and cause economic loss from damage to stored
foods and to physical facilities. Development of a comprehensive program to address a pest control problem,
including safe and appropriate pesticide application protocols, generally involves determining the scope and
magnitude of the problem(s), identifying appropriate expertise, defining who will do the work, devising a safe and
effective plan, implementing the program, continuously evaluating the program, and making program improvements
where necessary. Licensed animal facilities are required to maintain a pest management program (Animal Welfare
Act; 7 U.S.C. s/s 2131 et seq.).
A successful pest management program combines a thorough knowledge of both the biology of the pests in
question and the effects of any proposed control methods on the pests, and on the zoo's animal collection,
employees, and visitors (AAZV, 1999). The most successful control programs at zoos use integrated pest
management (IPM; Collins and Powell, 1996) as a pest management strategy, wherein natural processes (natural
pest mortality factors, pest-predator relationships, genetic resistance) can be manipulated to maximize their
effectiveness. Commonly, chemical controls are used only when natural processes of control fail (NRC, 1989b,
1996a) and in a way that minimizes economic, health, and environmental risks. The goal of IPM is to reduce pests to
a tolerable level through methods that are least disruptive to the environment.
CONSIDERATIONS FOR INTEGRATED PEST MANAGEMENT AT ZOOS
Key pest management issues at zoos are rat and mice control, insect (primarily cockroach) control,
nontarget concerns, and identification of nonchemical alternatives. A zoo poses unique problems because it is
necessary to control pests without harming exhibit specimens. Both the primary toxicity of the materials used as
well as relay toxicity should be considered (e.g., zoo animals consuming insects and dead rodents contaminated with
pesticide). Because of these risks, trapping is preferred over baiting for removal of vertebrate pests, unless there is
severe rodent overpopulation (Spelman, 1999). Fogging and fumigation should be strictly controlled, and only
certified, experienced applicators should be used. A pest management program should be the responsibility of senior
management personnel (limited to a very few people) who are knowledgeable about pest management principles.
Each aspect of the program should be reviewed prior to implementation, and chemical storage, inventories, safety
procedures, application techniques, and legal aspects (e.g., adherence to Environmental Protection Agency pesticide
and state or local rules and requirements for certified applicators, restricted use pesticides, use concentrations)
should be fully discussed before the pest management department conducts an application.
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56 ANIMAL CARE AND MANAGEMENT AT THE NATIONAL ZOO: INTERIM REPORT
Personnel directly responsible for the pest management program should be knowledgeable in all areas of
pest management operations and should regularly attend continuing education in professional pest management. The
input of management, curator staff, safety department, exhibit personnel, keepers, and the sanitation department is
essential for a successful pest management program.
A successful IPM program at a zoo includes several steps to control, reduce, or eliminate pests (Spelman,
1999). These may include inspection, exclusion and habitat management, sanitation, trapping, baiting, repellents,
and other methods. As a preventive measure routine inspection of animal facilities may identify a pest problem
before developing into an infestation. Physical barriers (e.g., fencing, netting, and roofing) provide a first line of
defense against pest infestation (Spelman, 1999). Habitat management is intended to reduce the attractiveness of an
animal enclosure to the pest.
Sanitation and proper storage and removal of solid waste (bedding, feed, enrichment items, dirt, and debris)
are important steps in pest management (AAZV, 1999). Appropriate food storage bins that are well sealed will
reduce potential pest problems. Cleaning and disinfecting food and water containers should occur routinely (AAZV,
1999). Public areas (e.g., walkways, concession areas) should be cleaned regularly, and the public should be
discouraged from feeding animals (Spelman, 1999). The Animal Welfare Act (7 U.S.C. s/s 2131 et seq.) contains
specific sanitization regulations for certain animals in captivity (e.g., indoor primary enclosures for nonhuman
primates must be sanitized at least once every two weeks).
Physical (trapping), chemical (baiting, repellents, and fumigation), and biological controls (predators,
contraceptive vaccines, species-specific disease) may need to be used for more severe pest infestations. Trapping of
pests reduces the risk of relay and nontarget toxicity that may occur in zoos, and it is preferred except in the cases of
severe rodent infestation (Spelman, 1999). Biological controls may be used in very specific situations when
carefully monitored (e.g., an oral contraceptive agent [viral vectored immunocontraception] may prove effective for
the control of feral rabbits and red fox (Holland and Robinson, 1995) although there is currently no biological
control for rodent infestations).
Chemical use should be considered a last resource for pest management because of the aforementioned
toxicity concerns; indeed, intoxication from chemical use in zoos has been reported many times. Pesticide use at
zoos is a concern because of potential impacts on animal health. At the National Zoo two red pandas died as a result
of ingesting aluminum phosphide placed in the animal enclosure to control a rodent infestation (see Box 4-1)
(Enquist and Montali, 2003). Second-generation anticoagulant rodenticides have been associated with toxicity and in
some circumstances death in several bird species: white-winged wood duck (James et al., 1998); turkey vultures,
kookaburra, von der Decken's hornbill, and crested wood partridge (Borst and Counotte, 2002). Additional specific
chemical toxicities in wildlife have been reviewed thoroughly (Fowler, 1978; Plumlee, 1997).
PEST MANAGEMENT AT THE NATIONAL ZOO
On January 10, 2003, when two red pandas consumed restricted-use fumigant tablets and later died, pest
management was the responsibility of the safety manager. Although a contractor applied the fumigant, the
application was carried out under the direction of an onsite zoo employee (a certified pesticide applicator located in
the Office of Safety) who manages some pest management programs. At the National Zoo at that time the certified
pesticide applicator was responsible for in-house chemical applications and baits targeted for insects, as opposed to
large treatments such as rat fumigation. To become a certified pesticide applicator, an individual must complete
training and pass an examination administered by the state or local authority that enforces Environmental Protection
Agency regulations for pesticides (Federal Insecticide, Fungicide, Rodenticide Act; 7 U.S.C. s/s 136 et seq. as
amended). This certification allows the person to purchase and apply restricted-use pesticides and is typically a
benchmark for training.
After the red panda deaths the National Zoo transferred responsibility for the Pest Management Program to
the Pathology Department. An Integrated Pest Management (IPM) committee has been formed to address the animal
and insect pest problem at the zoo. Since February 28, 2003, the IPM committee has conducted routine inspections
of the zoo to identify areas that require pest management attention (NZP, Integrated Pest Management Team
Review, September 22, 2003). Additionally, the National Zoo began the process of establishing a comprehensive
program to address the widespread pest problem (NZP, General Memorandum Draft, September, 2003), including
creation of a pesticide program manager position, which was subsequently filled by an entomologist with IPM
experience.
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PEST MANAGEMENT 57
BOX 4-1
Lack of Procedures Jeopardizes Animal Welfare: Red Panda (Accession #113194 and #111967) Deaths
Prior to the panda deaths the National Zoo was experiencing a growing rat problem. An outside contractor
was hired, but proper procedures were not in place to assure that the contractor was licensed and qualified to
perform necessary activities, including application of fumigant. Mothball-size pellets (approximately 3 grams each)
of aluminum phosphide were placed by the contractor with long-handled tongs approximately 2 feet deep in the rat
holes inside the parapet walls while the pandas were high up in 15-20 foot trees (see photo). During this activity
there was an animal attendant present. The pest holes were not all covered completely with steel plates (only eight or
nine were covered), and the applicator indicated that only seven burrows were filled with the fumigant (Fumitoxin
tablets - Pestcon Systems, Inc, http://ace.orst.edu/info/extoxnet/pips/alumphos.htm). The fumigant (phosphine gas)
is released upon contact with moisture. However, when the animals came down out of the trees they likely ingested
some of the pellets; pathology records show that both aluminum and phosphine were detected in the stomach
contents of both pandas. According to the pathology report, no signs of digging were noted in the panda yard, and it
is unlikely the pandas would be able to dig deeply enough to retrieve and ingest the pellets; the most likely scenario
is that the pandas (nocturnal animals) descended from the tree to investigate changes in their environment and, by
their curious behavior and investigative nature of tongue-tasting, ingested portions of the pellets remaining in the
yard. It is likely that they ingested fragments (product shelf life information suggests that some fragmentation may
occur) of pellets that were dropped/spilled during the application on the ground. The pandas were found dead at
approximately 9:00 a.m.
An outside contractor (not certified to apply pesticides in Washington, D.C.) had applied pesticide in the
panda yard, and there was no material safety data sheet (MSDS) for the pesticide, no formal use plan for the
fumigation, no safety policies, no posting of signs, no approval system prior to application, or pesticide use policy.
According to product label restrictions for Fumitoxin tablets: "The use of any pesticide in a manner that may kill
or otherwise harm an endangered or threatened animal or adversely modify their habitat is a violation of federal
laws." At the time of the investigation, information about the occurrence was scant. In response to this incident,
National Zoo management took the following actions:
Implementation of a procedure to approve the use of all chemicals, including pesticides.
Transferred responsibility of pesticide use to the Pathology Department.
Canceled the existing pest control contract.
Created and filled a new position of Pest Control Manager who reports to the Pathology Department.
Since the red panda deaths, a number of actions have been taken to address issues associated with both
vertebrate and insect pests at the zoo (NZP, Integrated Pest Management Team Review, September22, 2003):
Suspension of fumigation as a primary rat control technique.
Recovery of numerous poison bait boxes formerly used throughout the Rock Creek Park facility.
Assessment with recommendations for infrastructural pest exclusion procedures in many of the animal unit
facilities.
Incorporation of trash receptacles with water-shedding covers at secondary holding sites.
Introduction of animal food containers designed to exclude insects.
Rat activity assessment and trapping in major harborage sites.
Major roach reduction in a high-profile exhibit and holding areas with minimal pesticide application.
Implementation of improved animal food management and feeding times, and redesign of some outside
exhibits to reduce vermin attraction.
Trash management coordination of daily pickup and removal of trash by FONZ and National Zoo
personnel during peak visitor activity.
Mosquito, wasp, and yellow-jacket trapping and control, and elimination of mosquito breeding sites.
Educational sessions and reports on IPM activities to National Zoo and Smithsonian personnel.
Despite these efforts, housekeeping and site conditions are still poor in numerous areas throughout the zoo,
both in public and in nonpublic areas. Unsecured refuse (garbage in bags outside cans) and litter were observed
throughout the zoo complex. There is a lack of housekeeping and janitorial staff in public areas. Rodents (rats/mice)
were present in animal exhibition areas and were observed crossing public walkways in daylight, which is
significant because these pests are generally nocturnal. A Recent USDA inspection (USDA, 2004b) noted numerous
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58 ANIMAL CARE AND MANAGEMENT AT THE NATIONAL ZOO: INTERIM REPORT
mice were observed inside primate exhibit areas.
STRENGTHS AND WEAKNESSES IN PEST MANAGEMENT AT THE NATIONAL ZOO
Prompt and appropriate actions were taken after the deaths of the red pandas to address contributing
factors. These actions included reassignment of pest management responsibilities, cancellation of the existing pest
management contract, suspension of rat fumigation programs, formation of an IPM committee and draft of an IPM
plan, and creation of a professional pest control manager position (NZP, Integrated Pest Management Team Review,
September 22, 2003; NZP, General Memorandum Draft, September, 2003). However, emphasis on pest
management should continue to address the existing pest problem fully. Site observations indicate that considerable
work is necessary to ensure animal health and the aesthetic quality of the zoo (USDA, 2003). A comprehensive IPM
plan for pest management needs to be finalized and should
establish clear goals and objectives, (e.g., bring current populations of pests down to acceptable levels and
maintain those levels using modern IPM techniques incorporating routine management of sanitation,
janitoring, trapping, treatment, and inspection.
incorporate the input of management, curatorial staff, exhibit personnel, sanitation, facilities, and safety
personnel.
be under the leadership and direction of a pest management expert and the auspices of the pest management
department (other departments should not be allowed to alter or supplement the program).
consider consolidating the nutrition department so that food stock is in a central location.
include continued training, certification maintenance, and professional development for pest control
managers.
involve continuous reassessment and improvement.
Success in pest management has been achieved at other zoos with a comprehensive IPM plan (Collins and
Powell, 1996). With the widespread rodent problem the National Zoo may initially need to use chemical controls to
reduce rodent populations to levels that can be managed by nonchemical methods. Care should be exercised to select
the most suitable products or chemicals to minimize the hazards to nontarget animals. Ensuring that accidental
poisoning does not occur in the animal collection is a significant challenge. The Philadelphia Zoo has successfully
used hydrogen phosphide pellets and anticoagulants (bromadiolone) to control rat populations, but anticoagulants
(particularly brodifacoum) should not be used near bird collections because of its high toxicity (AAZV, 1999). Other
zoos have used expertise from the USDA-APHIS Wildlife Service Program for pest management.
Findings and Immediate Needs
Finding 6: Even though the pest management program has been reorganized and is showing signs of improvement,
pest management remains inadequate and poses a potential threat to the animal collection, employees, and visitors
to the National Zoo.
Immediate Needs: A comprehensive IPM plan should be developed: (1) in the short term to bring current
populations of pests down to acceptable levels and (2) in the long term to maintain those levels using modern IPM
techniques.
Representative terms from entire chapter:
national zoo
