Biology Reference
In-Depth Information
(see http://www.biosecurity.govt.nz/). Elements of that approach are applied in
other jurisdictions as well (e.g., Australia, South Africa). Most countries, however,
have avoided addressing the issue and lack any formal process for systematically
responding to invasive alien species that goes beyond ad hoc reaction.
Prevention
Successful prevention requires a clear understanding of how the organisms in
question are transported and what parameters determine pathway success rates.
For species that are introduced unintentionally as hitch-hikers on commercial
goods - such as many insects, other invertebrates, and agricultural weeds -
inspection and quarantine of arriving goods, containers, baggage, and vessels to
ensure they are pest-free will theoretically suffice to keep these pests out. For
organisms that are deliberately introduced - such as pets, biocontrol agents, and
food species - development of screening systems to assess the likelihood of the
species becoming established or becoming invasive are more appropriate. Species
deemed of high risk are prohibited from import; species of uncertain hazard are
also typically banned pending further assessment to clarify probability of
pestiferousness.
Quarantine inspection is typically directed to those articles considered at high
risk of harboring unwanted pests because the huge volume of traded material
makes it impossible to search all arriving items. Risk can be assigned to particular
commercial goods, types of packing material, types of vessels, or to arrivals from
particular source areas; it may be estimated using analysis of past interception
records, random searches of selected goods and baggage, or from “blitz” inspec-
tions that comprehensively search an entire shipment of goods or passengers.
Most high-risk materials will receive an inspection at the port-of-entry that may
vary in thoroughness depending on the resources available. High-risk commodi-
ties may be held in isolated quarantine facilities to determine whether they are
free of pests; this is most often done for living commodities, such as pets and
horticultural plants. As personnel and resources are available, effort may be
directed to articles of lesser risk. For governments having the resources, certifying
the pest-free status of commodities by examining them prior to export from the
country of origin can be a means of improving cleanliness of imported materials.
But this option is typically limited to inspection of agricultural commodities for
known, high-risk pests. Practical control methods at this stage typically involve
inspection for pests, treatment of articles suspected of harboring pests, and exclu-
sion of particular commodities via trade prohibition (Wittenberg and Cock,
2005). Treatment methods for contaminated plant produce are briefly reviewed
by Hallman (2007); several of these methods are useful as well for invasives that
do not target plants.
Two weaknesses characterize most inspection programs: (1) only a handful of
alien species are targeted quarantine pests, with the remainder ignored or allowed
