Environmental Engineering Reference
In-Depth Information
are 3,300 staff (inspection and non-inspection) in the agency that manages the
international border. Hence, to complement the eff ectiveness of the work done
by government agencies, there needs to be a high level of cooperation by a greater
part of the populace
The Queensland fruit fl y (
Bactrocera tryoni
) exemplifi es the combination of nat-
ural spread and host range extension resulting from human modifi cation of the
environment. It is native to south east Queensland, Australia, where it originally
lived on native fruit. When exotic horticultural species of fruit and vegetables were
introduced into its native range,
B. tryoni
was exposed to a novel host range to
which it readily adapted. It subsequently expanded its distribution to wide areas of
eastern Australia where it has severe consequences for some crops. High levels of
control and monitoring are required to ensure that major production areas are kept
free from this native, invasive species.
1.4.1.1 Natural disasters
Natural disasters affect the entry of invasive species. Cyclones (hurricanes) can
result in the movement of organisms over abnormally long distances. Similarly,
large-scale disturbance of landscapes can create conditions in which invasive
organisms can establish, e.g. the spread of insect vectors or large-scale destruc-
tion of land cover creates opportunities for establishment of weeds. In addition,
natural disasters often generate emergency relief actions and the rapid import-
ation of largely uncontrolled goods. The associated quarantine risks often lead to
accidental introductions (see Section 1.4.2).
There are many historical examples of accidental introductions, e.g. rodents
via ships, weeds in fodder, and European woodborer in furniture. More recent
examples include aquatic diseases introduced through ornamental fi sh and hyper-
parasites introduced with biological control agents. The impacts of such accidental
introductions can rival those of deliberate introductions. For example, there are
many documented examples of rodents causing at least local extinction of certain
bird species.
Most accidental introductions enter via contaminants of commodities or organ-
isms. h ey can also result from the deliberate introduction of another species upon
which they are parasites, e.g. parasitic mites of bumblebees introduced into Japan
for pollination purposes where the parasitic mites moved from the imported spe-
cies to native species where they have had a negative impact (Goka
et al.
2006).
1.4.2.1 Trade
Trade is the major pathway for short- and long-distance movement of small-
to-large quantities of materials and goods. Over recent decades, there have been vast
