Importance of psyllids’ life stage in the epidemiology of apple proliferation phytoplasma
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Phytoplasmas, microorganisms associated with severe plant diseases, are obligate parasites transmitted by phloem-feeding insects. Cacopsylla melanoneura and Cacopsylla picta are involved in the transmission of ‘Candidatus Phytoplasma mali,’ the etiological agent of apple proliferation (AP) disease. Research conducted in different geographic regions showed different transmission efficiencies for the two psyllids. In this study, acquisition and transmission trials were carried out to investigate the role of different life stages of these vectors in the epidemiology of AP after a sudden outbreak in northeastern Italy. Both species resulted able to acquire ‘Ca. P. mali,’ with higher infection rates recorded in C. picta. F1 generations showed a higher acquisition ability compared to adults in both species. ‘Ca. P. mali’ transmission was successful: Up to 1.5% of test plants were infected in trials with C. melanoneura and up to 10.2% in trials with C. picta. Overwintered adults of C. melanoneura showed a lower vectoring ability compared to C. picta. F1 nymphs and F1 adults, developed on infected plants, resulted in being competent vectors. Data on phytoplasma acquisition suggest a different relationship of ‘Ca. P. mali’ with the two species, evidencing a stronger affinity with C. picta. Moreover, taking into account the different factors influencing AP transmission, the probability of infection is mainly influenced by the presence of F1 nymphs and the phytoplasma load. In conclusion, this study evidences that C. picta is the most effective AP vector in the studied area, even if C. melanoneura can represent a potential risk in the presence of high inoculum sources.
KeywordsPsyllids vectors Phytoplasma Acquisition and transmission Apple proliferation ‘Candidatus Phytoplasma mali’
The authors thank Marco Deromedi for the assistance with insect rearing and care of stocked plant material, Christine Kerschbamer for her help with PCR analyses, and Hannes Schuler for the critical comments on the manuscript. The work was performed as part of SCOPAZZI-FEM, APPL2.0, and APPLClust projects and was partly funded by the Association of Fruit and Vegetable Producers in Trentino (APOT), the Autonomous Province of Bozen/Bolzano, and the South Tyrolean Apple Consortium.
Compliance with ethical standards
Conflict of interest
The authors have declared that no conflict of interest exists.
Research involving human participants and/or animals
This article does not contain any studies with human participants or animals (vertebrates) performed by any of the authors.
- Baric S, Öttl S, Dalla Via J (2009) Infection rates of natural psyllid populations with ‘Candidatus Phytoplasma mali’ in South Tyrol (Northern Italy). In: Paper presented at the 21st international conference on virus and other graft transmissible diseases of fruit crops, Neustadt, GermanyGoogle Scholar
- Bosco D, D’Amelio R (2010) Transmission specificity and competition of multiple phytoplasmas in the insect vector. In: Weintraub G, Jones P (eds) Phytoplasmas-genomes, plant hosts and vectors. CABI, London, pp 233–249Google Scholar
- Cainelli C (2007) Population dynamics of apple proliferation in Trentino. University of Verona, VeronaGoogle Scholar
- Carraro L, Ermacora P, Loi N, Osler R (2004) The recovery phenomenon in apple proliferation-infected apple trees. J Plant Pathol 86:141–146Google Scholar
- D’Amelio R, Palermo S, Marzachì C, Bosco D (2012) Influence of Chrysanthemum yellows phytoplasma on the fitness of two of its leafhopper vectors, Macrosteles quadripunctulatus and Euscelidius variegatus. Bull Insectol 61:349–354Google Scholar
- Fischnaller S, Parth M, Messner M, Stocker R, Kerschbamer C, Reyes-Dominguez Y, Janik K (2017) Occurrence of different Cacopsylla species in apple orchards in South Tyrol (Italy) and detection of apple proliferation phytoplasma in Cacopsylla melanoneura and Cacopsylla picta (Hemiptera: Psylloidea). Cicadina 17:37–51Google Scholar
- Hartig F (2018) DHARMa: residual diagnostics for hierarchical (multi-level/mixed) regression models. R package version 0.2.0 ednGoogle Scholar
- Jarausch W, Lansac M, Dosba F (1999) Seasonal colonization pattern of European stone fruit yellows phytoplasmas in different Prunus species detected by specific PCR. J Phytopathol 147:47–54Google Scholar
- Jarausch W, Peccerella T, Schwind N, Jarausch B, Krczal G (2003b) Establishment of a quantitative real-time PCR assay for the quantification of apple proliferation phytoplasmas in plants and insects. In: XIX international symposium on virus and virus-like diseases of temperate fruit crops-fruit tree diseases. vol 657, pp 415–420Google Scholar
- Jarausch B, Fuchs A, Schwind N, Krczal G, Jarausch W (2007) Cacopsylla picta as most important vector for ‘Candidatus Phytoplasma mali’ in Germany and neighbouring regions. Bull Insectol 60:189–190Google Scholar
- Krczal G, Grczal H, Kunze L (1988) Fieberiella florii (Stal), a vector of apple proliferation agent. Acta Hortic 235:99–106Google Scholar
- Lauterer P (1999) Results of the investigation on Hemiptera in Moravia, made by the Moravian museum (Psylloidea 2). Acta Musei Moraviae Sci Biol (Brno) 84:71–151Google Scholar
- Maggi F, Galetto L, Marzachì C, Bosco D (2014) Temperature-dependent transmission of Candidatus Phytoplasma asteris by the vector leafhopper Macrosteles quadripunctulatus Kirschbaum. Entomologia 2:87–94Google Scholar
- Malagnini V, Pedrazzoli F, Gualandri V, Zasso R, Bozza E, Fiamingo F, Pozzebon A, Mori N, Ioriatti C (2010) Detection of ‘Candidatus Phytoplasma mali’ in different populations of Cacopsylla melanoneura in Italy. Bull Insectol 366:59–63Google Scholar
- Marzachì C, Milne RG, Bosco D (2004) Phytoplasma-plant-vector relationships. In: Pandalai SG (ed) Recent research developments in plant pathology, vol 3. Signpost, Trivandrum, pp 211–241Google Scholar
- Mattedi L, Forno F, Varner M (2007) Scopazzi del melo. Conoscenze ed osservazioni di campo. Arti Garfiche La Commerciale-Borgogno, BolzanoGoogle Scholar
- Ossiannilsson F (1992) The psylloidea (homoptera) of fennoscandia and Demark. Brill, LeidenGoogle Scholar
- Pedrazzoli F (2009) Investigations on the psyllid (Hemiptera: Psyllidae) vectors of ‘Candidatus Phytoplasma mali’ in Trentino. University of Padua, PadovaGoogle Scholar
- Pedrazzoli F, Gualandri V, Forno F, Mattedi L, Malagnini V, Salvadori A, Stoppa G, Ioriatti C (2007) Acquisition capacities of the overwintering adults of the psyllid vectors of ‘Candidatus Phytoplasma mali’. Bull Insectol 60:195–196Google Scholar
- Schaper U, Seemüller E (1984) Recolonization of the stem of apple proliferation and pear decline-diseased trees by the causal organisms in spring. J Plant Dis Prot 91:608–613Google Scholar
- Tedeschi R, Bertignolo L, Alma A (2005) Role of the hawthorn psyllid fauna in relation to the apple proliferation disease. Petria 15:47–49Google Scholar