Biology Reference
In-Depth Information
need to be evaluated separately. It may be noted that, in CBD terminology, intro-
duction does not include establishment, and is thus effectively entry. This text fol-
lows IPPC terminology.
16.5.2.3
Probability of Entry
For quarantine pests other than invasive alien plants, there may be many alternative
pathways of entry to be considered. For any of these to be regulated in international
trade, the PRA should show that other relevant pathways have been considered.
Each has to be considered in turn.
For invasive alien plants, the possibilities of entry are in practice more limited.
Following Burgiel et al. (2006) and Genovesi (2007), pathways of entry of invasive
plants can be categorized as follows:
Intentional entry
Unintentional entry
Direct entry into the environment
Entry into a containment
facility or in a control-
led environment
The alien species unintention-
ally enters as a contaminant
of a specific commodity:
plant products such as plants
for planting, seeds, grain, and
soil and packaging
For ornament in landscaping
(the most frequent case)
In botanical and private
gardens
In greenhouses
For agriculture
In aquarium and horti-
cultural pond trade
For forestry
For research
The alien species unintention-
ally enters with movements
of people or of machinery
For invasive alien plants, the pathway most often assessed is intentional import for
ornamental purposes (including aquatic plants). In this case, entry is certain and
does not need to be considered as a variable. The assessor can go directly to the
probability of establishment (in particular the probability of establishment in non-
intended habitats).
Nevertheless, species introduced for ornament may also be introduced as contami-
nants. For instance, seeds of
Heracleum
spp. may contaminate soil and growing media.
In the cases that EPPO has considered so far, intentional entry was the only
pathway evaluated for
Crassula helmsii, Hydrocotyle ranunculoides, Lysichiton
americanus
and
Pueraria lobata
. In the other case (
Solanum elaeagnifolium
), unin-
tentional entry by several pathways was considered: contaminant of plants for
planting, soil/growing media, used machinery, grain, seeds for planting.
A plant associated with a pathway is assessed first for the probability that it
should enter, then for its survival during transport and its probability of transfer
