The African citrus psyllid Trioza erytreae : An efficient vector of Candidatus Liberibacter asiaticus Article - Décembre 2022

Bernard Reynaud, Patrick Turpin, Florencia M. Molinari, Martial Grondin, Solène Roque, Frédéric Chiroleu, Alberto Fereres, Hélène Delatte

Bernard Reynaud, Patrick Turpin, Florencia M. Molinari, Martial Grondin, Solène Roque, Frédéric Chiroleu, Alberto Fereres, Hélène Delatte, « The African citrus psyllid Trioza erytreae : An efficient vector of Candidatus Liberibacter asiaticus  », Frontiers in Plant Science, décembre 2022, p. 1089762. ISSN 1664-462X. 〈https://www.frontiersin.org/articles/10.3389/fpls.2022.1089762/full〉

Abstract

Introduction : Huanglonbing (HLB) is the most serious disease of citrus in the world, associated with three non-cultivable phloem-restricted bacteria Candidatus Liberibacter asiaticus (CLas), Ca L. africanus (CLaf) and Ca L. americanus (CLam). CLas is transmitted by the Asian citrus psyllid Diaphorina citri, and has spread to several countries. The African psyllid Trioza erytreae, the vector of CLaf occurs in Africa and neighbouring islands. Only two major citrus-growing regions - Australia/New Zealand and the Mediterranean Basin - are still HLB-free in the world. However, T. erytreae has recently been introduced into continental Europe (Portugal and Spain) and has become a potential threat to citrus production. The transmission of CLas by T. erytreae had been postulated but never tested. To evaluate the risk of T. erytreae transmitting CLas, comparative transmissions of CLas by T. erytreae and D. citri were assessed. Methods : Transmission tests were performed on excised leaves and seedlings of Citrus volkameriana with different inoculation access periods (in series) for both insect species. Quantifications of bacterial titers were made in excised leaves, seedlings three and six months after inoculation and on individual insects. Results : Our results showed that T. erytreae was able to efficiently acquire CLas. Furthermore, T. erytreae carried significantly higher bacterial titers than D. citri, and was able to efficiently transmit the bacteria to seedlings at a similar rate that D. citri highlighting the high risk of spread of the most aggressive variant of HLB (CLas) by T. erytreae in Europe. Discussion : Thus, extreme precautions to prevent any entry of CLas into Europe should be adopted.

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