Scientific opinion on a quantitative pathway analysis of the likelihood of Tilletia indica M. introduction into EU with importation of US wheat


Panel on Plant Health
EFSA Journal
EFSA Journal 2010; 8(6):1621 [88 pp.].
Panel Members
Richard Baker, Thierry Candresse, Erzsébet Dormannsné Simon, Gianni Gilioli, Jean-Claude Grégoire, Michael John Jeger, Olia Evtimova Karadjova, Gábor Lövei, David Makowski, Charles Manceau, Maria Navajas, Angelo Porta Puglia, Trond Rafoss, Vittorio Rossi, Jan Schans, Gritta Schrader, Gregor Urek, Johan Coert van Lenteren, Irene Vloutoglou, Stephan Winter and Marina Zlotina. One member of the Panel did not participate in the discussion on the subject referred to above because of potential conflicts of interest identified in accordance with the EFSA policy on declarations of interests.

The Panel wishes to thank: the members of the Working Group on Tilletia indica for the preparatory work for this opinion: Michael John Jeger, Gábor Lövei, David Makowski, Angelo Porta Puglia, Trond Rafoss and Irene Vloutoglou; the hearing expert Guillermo Fuentes Dávila for the presentations on biological and epidemiological aspects of Karnal bunt; the hearing experts Filippo Bertuzzi, Luigi Pianu and Roberto Ranieri for the presentation on the wheat pathway and the Italian durum wheat milling industry; and EFSA’s staff members Olaf Mosbach-Schulz, Giuseppe Stancanelli and Tilemachos Goumperis for the support provided to this EFSA scientific output.

Opinion of the Scientific Committee/Scientific Panel
On request from
European Commission
Question Number
11 May 2010
Published in the EFSA Journal
18 June 2010
European Food Safety Authority (EFSA), Parma, Italy

The European Commission requested EFSA to provide a scientific opinion on the USDA APHIS quantitative pathway analysis on likelihood of Karnal bunt introduction with importation of US wheat for grain into EU and desert durum wheat for grain into Italy. EFSA was also requested to indicate whether the US bunted kernel standard would provide equivalent protection against introduction of Tilletia indica into EU, compared to the existing EU import requirement. The Panel on Plant Health reviewed pathway scenarios, model and parameters and found several shortcomings regarding model equations and parameter values, particularly a lack of scientific evidence for the infection threshold. Simulations were computed, for importations of US wheat into EU and desert durum wheat into Italy, based on original model and an updated model with revised parameter values. Model output was teliospores number per hectare on soil surface of each EU country. Simulated teliospores numbers entering EU were lower with the updated than with the original model. These results showed a high uncertainty, underestimated with the original model, over the number of teliospores entering each EU country. Sensitivity analysis showed several key parameters (proportion of bunted kernels in Arizona regulated counties, number of Arizona positive hectares and number of teliospores per bunted kernel) strongly influencing number of teliospores entering the EU. In addition, high sensitivity indices were obtained with the updated wheat model for several parameters related to EU country characteristics. Further research is needed to refine parameter values, to reduce uncertainty and to determine relationship between teliospores number on soil surface and number of bunted kernels resulting from infection of a wheat plant. The Panel concluded that the US bunted kernel standard does not provide a level of protection equivalent to EU requirements and that such level of protection could only be warranted by measures which include testing at harvest and before shipment to detect T. indica teliospores.

Wheat, durum wheat, desert durum, grain, import, mill, pathway, Karnal bunt,Tilletia indica, teliospores, model, stochastic, probabilistic.
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