EFSA’s environmental risk assessment of the apple snail for the EU: a novel approach

In the context of a pest risk assessment, the potential consequences caused by a harmful organism needs to be estimated including the environmental consequences, besides the evaluation of other risk components. This publication describes a novel approach that was developed by the Panel on Plant Health (Panel) of the European Food Safety Authority (EFSA) and used to perform the environmental risk assessment for the apple snails for the EU. Apple snails are considered to be serious rice pests and can cause devastating effects on the flora and fauna of natural wetlands. In 2010 the Island apple snail, Pomacea maculata, started its invasion in the rice fields in the Ebro Delta in Spain where it is currently still spreading. Today, the snail is not only present in rice paddies but also in some nearby wetlands, and it has been found moving upwards along the Ebro riverbeds. In 2012, on the request of the European Commission, the EFSA Panel on Plant Health (Panel) evaluated a Spanish pest risk analysis on the apple snail (Spanish Ministry of Environment and Rural and Marine Affairs, 2011) and concluded that the risk posed by the apple snail to the natural environment was not sufficiently addressed and recommended that further study should be performed. Consequently the Panel was requested by EFSA to perform an environmental risk assessment on the apple snail for the EU. The snail population density was identified as the driver of the ecosystem change, and therefore the factor playing the major role in determining the impact of the snail on the environment. The Panel developed a population dynamics model to estimate the potential population densities of snail eggs, juveniles and adults, and to identify the potential snail hot spots in Europe. As a result maps were generated to represent the potential snail density distribution in the EU territory (EFSA PLH Panel, 2013). The environmental risk assessment procedure developed by the Panel and presented in its guidance document (EFSA Panel on Plant Health, 2011) was used to assess the negative impact of the snail invasion on the shallow freshwater areas containing macrophytes such as wetlands, shallow lakes, river deltas and the littoral zone of deeper lakes and rivers in Europe (EFSA PLH Panel, 2014). This work has been published in two scientific opinions by the EFSA Panel on Plant Health and the key aspectsfrom these scientific opinions are presented in this paper.