Pest risk assessment of Elasmopalpus lignosellus for the European Union

Abstract

Abstract Following a request from the European Commission, the EFSA Panel on Plant Health performed a quantitative pest risk assessment of Elasmopalpus lignosellus (Lepidoptera: Pyralidae), the lesser cornstalk borer, for the EU. The assessment considered entry, establishment, spread and impact. Two scenarios for establishment were considered: (i) under current climatic conditions and (ii) under a future climate based on an ensemble of climate change scenarios. Impact assessment focused on cereal and legume host species. E. lignosellus is not known to occur outside of the Americas although it has been intercepted in the EU on fresh asparagus spears for consumption. Based on the size of the trade and evidence of interceptions, the importation of asparagus from Peru was identified as the most important pathway for entry. Using stochastic pathway modelling with parameter values based on Eurostat data and expert knowledge elicitation (EKE), the Panel estimated the median number of infested asparagus spears entering the EU annually to be approximately 8,600 (90% certainty range (CR) approximately 1,300–58,500). Each infested spear is likely to contain only one larva. Conditions are most suitable for establishment in the southern EU, especially around the Mediterranean basin. Under current climatic conditions, around 16% of spears enter regions of the EU suitable for establishment; this rises to 24% in the climate change scenario considered (2040–2059). However, due to estimated small likelihoods of adults emerging and escaping from discarded waste, finding a mate and the subsequent progeny surviving to initiate a founder population, the median number of populations expected to establish was estimated to be 0.0001 per year (90% CR 0.000005–0.002). Were E. lignosellus to establish, the median rate of natural spread was estimated to be 7.4 km/year (90% CR 0.6–18.2 km/year), after an initial lag period of 18.5 years (90% CR 3.3–43.8 years) following the establishment of a founder population. Estimated median yield losses in crops of cereals and legumes were estimated to be 0.95% (CR 0.2–2.8%), assuming farmers would adapt control measures such as are in place for other seedling pests. The Panel did not consider a scenario with additional risk reduction options because no feasible options at field level could be identified while export inspections aiming for zero contamination of the commodity are already in place in the exporting country – Peru.

Keywords

• @risk
• climate change
• expert knowledge elicitation (EKE)
• lesser cornstalk borer
• quantitative PRA
• pathway model