Studies on insect vectors of Xylella fastidiosa in Taiwan
Since 2002, a survey project has been launched to investigate the occurrence of Pierce’s disease caused by Xylella fastidiosa (EPPO A1 List) in Taiwan. It can be recalled that in Taiwan, X. fastidiosa was first recorded on Asian pear (Pyrus pyrifolia) in the 1990s and more recently on grapevine (see EPPO RS 1994/049, 1996/204, 2007/187 and 2013/118). Molecular studies have shown that the bacteria isolated from Taiwan and the USA were related, but that the X. fastidiosa strains from Taiwan isolated from grape and pear were generally different from each other. According to investigations carried from 2003 to 2012, Pierce’s disease has been diagnosed in a total of 399 vineyards (13 666 grapevine plants), including both table and vine cultivars. Previous studies have suggested that Kolla paulula and Bothrogonia ferruginea (Hemiptera: Cicadellidae) were candidate insect vectors of X. fastidiosa in Taiwan. Recent studies have confirmed that both insect species were vectors of X. fastidiosa and could transmit the bacterium from diseased to healthy grapevines. The acquisition rates by K. paulula and B. ferruginea from infected grapevines (Vitis vinifera x V. labrusca cv. ‘Golden Muscat’) were approximately 83 and 70%, respectively. The transmission rates from symptomatic grapevines (Vitis vinifera x V. labrusca cvs. ‘Golden Muscat’ and ‘Black Queen’) to healthy ones were approximately 55 and 50%, respectively. The life cycles of these insects were also studied. It is noted that both species have a broad host range and are highly mobile. They mainly feed on weeds and move occasionally to grapevine. K. paulula might be more effective than B. ferruginea as a vector of X. fastidiosa, but further studies are needed to confirm their respective role and ability to induce Pierce’s disease epidemics.
Sources
Tuan SJ, Hu FT, Chang HY, Chang PW, Chen YH, Huang TP (2016) Xylella fastidiosa transmission and life history of two Cicadellinae sharpshooters, Kolla paulula and Bothrogonia ferruginea (Hemiptera: Cicadellidae), in Taiwan. Journal of Economic Entomology 109(3), 1034-1040.