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

TITLE=The African citrus psyllid Trioza erytreae: An efficient vector of Candidatus Liberibacter asiaticus

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1089762

DOI=10.3389/fpls.2022.1089762

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Huanglonbing (HLB) is the most serious disease of citrus in the world, associated with three non-cultivable phloem-restricted bacteria <italic>Candidatus</italic> Liberibacter asiaticus (<italic>C</italic>Las), <italic>Ca</italic> L. africanus (<italic>C</italic>Laf) and <italic>Ca</italic> L. americanus (<italic>C</italic>Lam). <italic>C</italic>Las is transmitted by the Asian citrus psyllid <italic>Diaphorina citri</italic>, and has spread to several countries. The African psyllid <italic>Trioza erytreae</italic>, the vector of <italic>C</italic>Laf 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, <italic>T. erytreae</italic> has recently been introduced into continental Europe (Portugal and Spain) and has become a potential threat to citrus production. The transmission of <italic>C</italic>Las by <italic>T. erytreae</italic> had been postulated but never tested. To evaluate the risk of <italic>T. erytreae</italic> transmitting <italic>C</italic>Las, comparative transmissions of <italic>C</italic>Las by <italic>T. erytreae</italic> and <italic>D. citri</italic> were assessed.</p></sec><sec><title>Methods</title><p>Transmission tests were performed on excised leaves and seedlings of <italic>Citrus volkameriana</italic> 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.</p></sec><sec><title>Results</title><p>Our results showed that <italic>T. erytreae</italic> was able to efficiently acquire <italic>C</italic>Las. Furthermore, <italic>T. erytreae</italic> carried significantly higher bacterial titers than <italic>D. citri</italic>, and was able to efficiently transmit the bacteria to seedlings at a similar rate that <italic>D. citri</italic> highlighting the high risk of spread of the most aggressive variant of HLB (<italic>C</italic>Las) by <italic>T. erytreae</italic> in Europe.</p></sec><sec><title>Discussion</title><p>Thus, extreme precautions to prevent any entry of <italic>C</italic>Las into Europe should be adopted.</p></sec>