Risk assessment of Resseliella citrifrugis for the EU

Bragard, Claude [UCL] Baptista, Paola Chatzivassiliou, Elisavet Di Serio, Francesco Gonthier, Paolo Jaques Miret, Josep Anton Justesen, Annemarie Fejer MacLeod, Alan Magnusson, Christer Sven Milonas, Panagiotis Navas‐Cortes, Juan A Parnell, Stephen Potting, Roel Reignault, Philippe Lucien Stefani, Emilio Thulke, Hans‐Hermann van der Werf, Wopke Yuen, Jonathan Zappalà, Lucia Makowski, David Crotta, Matteo Maiorano, Andrea Pautasso, Marco Vicent Civera, Antonio et al.[show all]

Following a request from the European Commission, the EFSA Panel on Plant Health performed a risk assessment of the citrus fruit midge Resseliella citrifrugis (Diptera: Cecidomyiidae), an oligophagous species, which feeds on fruits of Citrus spp., and is reported from China. The pest was temporarily regulated in October 2022 (Regulation (EU) 2022/1941, under Art. 30 (2016/2031)). The entry risk assessment focused on the citrus fruit pathway. Three scenarios were considered: A0 (current practice, i.e. regulated pest for the EU), A1 (deregulation) and A2 (A0 with additional stand‐alone post‐harvest cold treatment). Based on the outputs of the entry model, under scenario A0, slightly less than 40 potential founder populations per year are expected (median; 90%‐uncertainty interval between about one per 30 years and about 3,000 per year). Under scenario A1, the risk of entry increases by about three times and reaches about 120 potential founder populations per year (median; 90%‐uncertainty interval between about one per 10 years and about 9,000 per year). Compared to scenario A0, the risk of entry is orders of magnitude lower for scenario A2 (median = about one potential founder population per 120 years; 90%‐uncertainty interval between one per about 600 million years and about two per year). The main uncertainties in the entry assessment are the probability of transfer, the RRO effectiveness (for scenario A2) and the disaggregation of consignments (transport of citrus fruit in boxes or lots to different locations). For all scenarios, the number of established populations is only slightly lower than the number of potential founder populations. Establishment is thus not expected to be a major constraint for this pest to then spread and cause impacts, despite the uncertainty about the pest thermal requirements. The median lag period between establishment and spread is estimated to be about 18 months (90%‐uncertainty interval between about 7 and 54 months). After the lag period, the median rate of spread by flying and due to transport of harvested citrus fruit from orchards to packinghouses is estimated at about 100 km/year (90%‐range between about 40 and 500 km/year). The main uncertainties in the spread assessment include the level of susceptibility of cultivars of different citrus species in the EU, the spread rate in China and the climate suitability of the initial spread focus in the EU. The median impact of R. citrifrugis in the EU citrus‐growing area (proportion of infested citrus fruit out of harvested citrus fruit) is estimated at about 10% (90%‐uncertainty interval between about 2% and 25%). Uncertainties affecting the impact assessment include the susceptibility of different citrus cultivars and the effect of the citrus fruit‐harvesting season in the EU (mainly winter, the less suitable season for the pest).