77
6
Likelihood of Introducing
Nonindigenous Organisms with
Agricultural Commodities:
Probabilistic Estimation
Michael J. Firko and Edward V. Podleckis
Introduction
When nonindigenous organisms become established in new areas, biodiversity is
altered, and there may be direct impacts on indigenous species as well as disruption of communities and ecosystems. The frequency of species introductions into
the United States has increased dramatically during the past 100 years, primarily
because of human activities (OTA 1993). The advent of regular long-range human
movements and increased trade in international markets has added to the global
dissemination of organisms. Plant Protection and Quarantine (PPQ) within the
Animal and Plant Health Inspection Service (APHIS) of the U.S. Department
of Agriculture (USDA) intercepts tens of thousands of nonindigenous plant
pests every year in passenger baggage, in ships’ stores, and in agricultural
commodities—both legal and smuggled.
Many introductions that occur are difficult to manage. For example, it is believed that the Zebra Mussel (Dreissena polymorpha Pallas) was introduced when
commercial ships in North American waterways discharged ballast water taken on
in foreign ports. Sailer (1978) discussed exotic insect fauna in the United States.
Well-known introduced plant pests include Gypsy Moth, Japanese Beetle, Chestnut Blight, Dutch Elm Disease, and Karnal Bunt of wheat.
Commercial trade in living nonindigenous organisms has led to many introductions. The U.S. Congress Office of Technology Assessment (OTA) found that
importations by the nursery, pet, and aquaculture industries constitute a major
source of introductions (OTA 1993). And although nonindigenous biological
control agents such as parasitic wasps and plant pathogens have been imported
and released for many years, activity in this area has increased markedly during
the past decade with the development of international markets for mass-produced
biological control agents. Simberloff and Stiling (1996) discussed risks associated
with purposeful introductions of biological control organisms. Release of nonindigenous biological control organisms—as well as other biologically based technologies for pest control—was also considered by OTA (1995). Bennett (1993)
discussed replacement of native parasitoids by exotic species, and several specific
issues related to release of nonindigenous biological control agents for control of
6
Likelihood of Introducing
Nonindigenous Organisms with
Agricultural Commodities:
Probabilistic Estimation
Michael J. Firko and Edward V. Podleckis
Introduction
When nonindigenous organisms become established in new areas, biodiversity is
altered, and there may be direct impacts on indigenous species as well as disruption of communities and ecosystems. The frequency of species introductions into
the United States has increased dramatically during the past 100 years, primarily
because of human activities (OTA 1993). The advent of regular long-range human
movements and increased trade in international markets has added to the global
dissemination of organisms. Plant Protection and Quarantine (PPQ) within the
Animal and Plant Health Inspection Service (APHIS) of the U.S. Department
of Agriculture (USDA) intercepts tens of thousands of nonindigenous plant
pests every year in passenger baggage, in ships’ stores, and in agricultural
commodities—both legal and smuggled.
Many introductions that occur are difficult to manage. For example, it is believed that the Zebra Mussel (Dreissena polymorpha Pallas) was introduced when
commercial ships in North American waterways discharged ballast water taken on
in foreign ports. Sailer (1978) discussed exotic insect fauna in the United States.
Well-known introduced plant pests include Gypsy Moth, Japanese Beetle, Chestnut Blight, Dutch Elm Disease, and Karnal Bunt of wheat.
Commercial trade in living nonindigenous organisms has led to many introductions. The U.S. Congress Office of Technology Assessment (OTA) found that
importations by the nursery, pet, and aquaculture industries constitute a major
source of introductions (OTA 1993). And although nonindigenous biological
control agents such as parasitic wasps and plant pathogens have been imported
and released for many years, activity in this area has increased markedly during
the past decade with the development of international markets for mass-produced
biological control agents. Simberloff and Stiling (1996) discussed risks associated
with purposeful introductions of biological control organisms. Release of nonindigenous biological control organisms—as well as other biologically based technologies for pest control—was also considered by OTA (1995). Bennett (1993)
discussed replacement of native parasitoids by exotic species, and several specific
issues related to release of nonindigenous biological control agents for control of