Scientific Opinion on the assessment of the potential establishment of the apple snail in the EU

EFSA requested the PLH Panel to review the current state of the art of the biology and ecology of apple snails,
reported in this opinion, and to perform an environmental risk assessment for validation of the Plant Health
environment guidance document, which will be provided in a second opinion. The Panel presents in this opinion
the current state of the art of the biology of apple snails, and develops and uses a population dynamics model to
assess the potential establishment of apple snails in the EU. A thorough review of the literature on the biology of
Pomacea canaliculata and P. maculata was performed to collect information and data on life history
characteristics related to temperature, which was used in the population dynamics model. Although uncertainties
on the systematics and taxonomy of the genus Pomacea remain, it is now acknowledged that Pomacea
insularum is a synonym of P. maculata and can be undoubtedly differentiated from P. canaliculata. Natural
spread occurs via rivers and canals, in which the snails crawl, drift, float and raft. Flooding increases spread. In
addition, attachment to animals (e.g. birds, cattle, horses, deer and aquatic invertebrates) results in spread.
Human assistance results in spread through cultivation transport of rice seedlings, aquaculture, aquaria, boats,
and agricultural field machinery. The potential distribution of P. canaliculata in Europe was obtained by
calculating with the population dynamics model, the average snail abundance per year in each node of a grid of
0.25 × 0.25 degrees covering Europe, which resulted in the following conclusions: (1) the area of potential
establishment comprises wetlands of southern Europe (i.e. Spain, southern France, most of Italy and Greece) and
the Balkans up to the latitude of the Danube river, (2) the potential area of establishment includes the rice
production areas in Europe.