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The psyllids Cacopsylla melanoneura and Cacopsylla picta reproduce on apple (Malus × domestica) and transmit the bacterium ‘Candidatus Phytoplasma mali’, the causative agent of apple proliferation. Adult psyllids were collected by the beating-tray method from lower and upper parts of the apple tree canopy in the morning and in the afternoon. There was a trend of catching more emigrant adults of C. melanoneura in the morning and in the lower part of the canopy. For C. melanoneura remigrants, no differences were observed. The findings regarding the distribution of adults were reflected by the number of nymphs collected by wash-down sampling. The density of C. picta was too low for a statistical analysis. The vector monitoring and how it is commonly performed, is suitable for estimating densities of C. melanoneura. Nevertheless, above a certain temperature threshold, prediction of C. melanoneura density might be skewed. No evidence was found that other relatively abundant psyllid species in the orchard, viz. Baeopelma colorata, Cacopsylla breviantennata, Cacopsylla brunneipennis, Cacopsylla pruni and Trioza urticae, were involved in ‘Candidatus Phytoplasma mali’ transmission. The results of our study contribute to an advanced understanding of insect vector behavior and thus have a practical impact for an improved field monitoring.

The phloem-sucking psyllid Cacopsylla picta Forster, 1848 (C. picta) plays an important role in transmitting the bacterium ‘Candidatus Phytoplasma mali’ (‘Ca. P. mali’), the causative agent of apple proliferation disease. The psyllid can ingest ‘Ca. P. mali’ from infected apple trees and spread the bacterium by subsequently feeding on uninfected trees. Until now, this is the most important way of ‘Ca. P. mali’ transmission. The aim of this study was to investigate if infected C. picta are able to transmit ‘Ca. P. mali’ directly to their progeny. This method of transmission would allow the bacteria to bypass a time-consuming reproductive cycle in the host plant. Furthermore, this would cause a high number of infected F1 individuals in the vector population. To address this question, eggs, nymphs and adults derived from infected overwintering adults of C. picta were reared on non-infected apple saplings and subsequently tested for the presence of ‘Ca. P. mali’. In this study it was shown for the first time that infected C. picta individuals transmit ‘Ca. P. mali’ to their eggs, nymphs and F1 adults, thus providing the basis for a more detailed understanding of ‘Ca. P. mali’ transmission by C. picta. This article is protected by copyright. All rights reserved.

The apple proliferation (AP) disease is spread mostly by two psyllids. Each species plays a predominant role as AP vector that changes regionally. Thus, there is an urgent need to identify the AP vectors in each region where the disease is present. This research aimed at identifying the psyllid community in apple orchards from Asturias (NW Spain) and studying their possible role in AP transmission. Yellow sticky traps were used to monitor psyllid community in five cider-apple orchards during 2 years. 3678 individuals belonging to 22 species were identified. We confirmed the presence of the two known vectors, Cacopsylla picta and Cacopsylla melanoneura, although they occurred in relatively low numbers (2.1 and 0.7 % of total catches, respectively). Most collected psyllids are not supposed to use apple as host, and their occurrence is likely favoured by landscape structure and an insect-friendly management. Phytoplasma detection was performed by squash-capture real-time PCR. The pathogen was detected in six species (Cacopsylla crataegi, Cacopsylla mali, Ctenarytaina spatulata, Ctenarytaina eucalypti and the two known AP vectors). Based on abundance and AP-detection rate C. picta is likely the main species spreading AP in our region. However, the low density of the known vectors does not match the widespread and high tree damage level observed in Asturias. The discovery of other four psyllid species carrying the phytoplasma reveals that our knowledge on the potential vectors is limited and that more research is clearly needed to unravel the role of the psyllid fauna in disease transmission in our orchards.

Sudtirol ist mit 18.538 ha Anbauflache das groste zusammenhangende Apfelanbaugebiet Europas. Mit 1,18 Mio. t an produzierten Apfeln (2011), mehr als die Halfte der Produktion Italiens, kommt jeder neunte in der EU-27 produzierte Apfel aus Sudtirol. 53 % der gesamten Wertschopfung aus der Landwirtschaft Sudtirols stammt aus dem Apfel-Anbau, auf nur 7,7 % der landwirtschaftlichen Nutzflache Sudtirols. In der vorliegenden Arbeit wird die Entwicklung der obstbaulichen Forschung beschrieben und wie sie sich aus dem historischen Kontext entwickelt hat. Aus konkreten Anbaufragen, dem Auftreten der ersten globalen Schadlinge (Mehltau, Falscher Mehltau, Apfel-Schorf, Blutlaus, Blutenstecher, Apfelwickler, Maikafer), und der Suche nach Losungen zu deren Bekampfung, wird im 19. Jahrhundert der Ruf nach fachlicher Begleitung, Beratung, Weiterbildung und Forschung immer lauter. Am 10. November 1874 wird das ‘Istituto agrario e stazione sperimentale’ in St. Michael an der Etsch eroffnet, das fortan die Landwirtschaft des heutigen Sudtirol und Trentino begleitet. Mit Ende des Ersten Weltkrieges und der folgenden Italianisierung Sudtirols bricht die landwirtschaftliche Versuchstatigkeit und Ausbildung zusammen. Erst nach dem Zweiten Weltkrieg beginnt wieder der Aufbau der landwirtschaftlichen Aus- und Weiterbildung in deutscher Sprache und die jungen landwirtschaftlichen Fachschulen ubernehmen zwischenzeitlich auch die obstbauliche Versuchstatigkeit im Lande. Mit dem zweiten Autonomiestatut 1972 geht die Kompetenz zur Errichtung landwirtschaftlicher Versuchsanstalten an die Autonome Provinz Bozen uber und mit dem 1. Janner 1976 wird das ‘Land- und Forstwirtschaftliche Versuchszentrum Laimburg’ gegrundet, als Forschungsinstitution der gesamten landwirtschaftlichen Forschung Sudtirols, der angewandten wie auch der Grundlagen-Forschung. Die Entwicklung vieler Forschungsbereiche und deren Meilensteine werden aufgezeigt: Anbausysteme, Bodenpflege und Dungung, die Entwicklung des Kernobstsortimentes, die Sortenprufung und Sortenzuchtung, der Aufbau des Baumschulwesens, die Bewasserung, der Pflanzenschutz mit der Maikaferbekampfung, vom Apfelwickler bis zur Kirschessigfliege, vom Besenwuchs bis zum Feuerbrand, vom Apfelschorf bis zum ‘Weisen Hauch’ und den Blattfleckenkrankheiten, sowie die Entwicklung neuer Lagertechnologien, die Begleitung des Biologischen Anbaus bis hin zur Molekularbiologie und der Entwicklung neuer diagnostischer Methoden. Ausgehend von einem 2-Mann-Team der Grunderzeit umfasst das Land- und Forstwirtschaftliche Versuchszentrum Laimburg, mit seinen uber 20 Ausenstellen heute einen Personalstand von nahezu 200 Mitarbeitern und Mitarbeiterinnen, bearbeitet jahrlich an die 400 Projekte und Tatigkeiten und ist eine anerkannte landwirtschaftliche Forschungsinstitution in Europa. Die neuen geplanten Baulichkeiten, zusammen mit den landwirtschaftlichen Fachschulen und der Freien Universitat Bozen, werden aus dem Standort ‘Laimburg’ ein Zentrum der Landwirtschaftlichen Forschung sowie Aus- und Weiterbildung begrunden, sodass die zukunftigen Forschungsfragestellungen im Obstbau mit Zuversicht gemeistert werden konnen.

We elucidated the life cycles of two jumping plant lice species (Hemiptera: Psyllidae): Cacopsylla picta, a vector of the apple proliferation phytoplasma (Candidatus Phytoplasma mali), and Cacopsylla melanoneura, a nonvectoring species in Germany and some neighbouring countries, which may transmit the phytoplasma in one region in Italy. 2 The adults of C. picta reproduce exclusively on apple and migrate soon after emergence (emigrants) to conifers in mountainous regions, and return to apple plants in early spring (remigrants). Cacopsylla melanoneura also uses conifers as overwintering host plants but prefers to reproduce on hawthorn, despite its ability to reproduce on apple. 3 Both psyllid species used chemical cues for the identification of their alternate host plants during migration. Remigrants of C. melanoneura preferred the odour of their main reproduction host plant hawthorn to apple but preferred the odour of apple when experienced by feeding and oviposition. Although emigrants of C. picta report- edly prefer the odour of apple trees infected by Ca. P. mali, the remigrants of both species did not distinguish between the odours of infected or uninfected apple plants. 4 Investigating the distribution of Ca. P. mali in plant species involved in psyllid life cycle revealed that the phytoplasma is specialized on apple. 5 Infection of apple by Ca. P. mali increased mortality and resulted in decreased body size of C. picta offspring. 6 Gravid females of C. picta preferred to oviposit on non-infected plants. 7 It is concluded that Ca. P. mali indirectly promotes its acquisition from infected plants and transmission to non-infected plants by behavioural manipulation of its vector C. picta.

Cacopsylla picta (Foerster, 1848) Psylla picta Foerster, 1848: 81. MATERIAL EXAMINED. — France. Alpes-Maritimes, Saorge, M10- CAI1400-T5-M2, 1♂ (MNHN). DISTRIBUTION. — Fauna Europaea: Austria, Belgium, Czech Republic, Finland, France, Germany, Italy, Moldova, Slovakia, Sweden, Switzerland, Ukraine; INPN: no data; additional data from Psyl’list: Bulgaria, Great Britain, Slovenia. COMMENTS Description in Ossiannilsson (1992), as Cacopsylla (Thamnopsylla) costalis (Flor, 1861), and Burckhardt (2010). Biology in Ossiannilsson (1992). Host-plants: several species of Malus (Rosaceae). Cacopsylla propinqua (Schaefer, 1949) (Fig. 1A) Psylla propinqua Schaefer, 1949: 37. MATERIAL EXAMINED. — France. Alpes-Maritimes, Saint-Dalmasde-Tende, Lac de la Muta, 2365 m, 44°2’57.2742”N- 7°26’5.694”E, 18.VII.2009, C. Cocquempot (CBGP), 1 adult. DISTRIBUTION. — Fauna Europaea: Finland, Germany, Italy, Norway, Russia, Slovakia (doubtful), Sweden, Switzerland; INPN: no data; additional data from Psyl’list: no additional data. COMMENTS Description in Schaefer (1949) and Conci & Tamanini (1986a). Biology in Conci et al. (1993). Host-plants: several species of Salix (Salicaceae). New for France., Published as part of Ouvrard, David, Burckhardt, Daniel & Cocquempot, Christian, 2015, An annotated checklist of the jumping plant-lice (Insecta: Hemiptera: Psylloidea) from the Mercantour National Park, with seven new records for France and one new synonymy, pp. 251-271 in Zoosystema 37 (1) on page 259, DOI: 10.5252/z2015n1a13, http://zenodo.org/record/5155473, {"references":["OSSIANNILSSON F. 1992. - The Psylloidea (Homoptera) of Fennoscandia and Denmark. Fauna Entomologica Scandinavica, Volume 26. E. J. Brill, Leiden, New York, 346 p.","BURCKHARDT D. 2010. - Pictorial key of Central European Cacopsylla species associated with Rosaceae, http: // www. psyllidkey. com / index. html","SCHAEFER H. A. 1949. - Beitrage zur Kenntnis der Psylliden der Schweiz. Mitteilungen der schweizerischen entomologischen Gesellschaft 22 (1): 1 - 96.","CONCI C. & TAMANINI L. 1986 a. - Cacopsylla propinqua, from Valle d'Aosta, new for Italy (Homoptera Psylloidea). Doriana 6: 1 - 8.","CONCI C., RAPISARDA C. & TAMANINI L. 1993. - Annotated catalogue of the Italian Psylloidea. First part. (Insecta Homoptera). Atti della Accademia Roveretana degli Agiati Serie 7 B Classe di Scienze Matematiche Fisiche e Naturali 2 B: 33 - 135."]}

Des prospections ont ete menees a l'automne 2004 et au printemps 2005 dans les zones traditionnellement dediees a la culture des fruits a pepins et a noyaux en Bosnie-Herzegovine pour evaluer la presence, la distribution et l'incidence des maladies a phytoplasme dans les arbres fruitiers. La presence de psylles vecteurs a egalement ete etudiee. La detection de phytoplasmes dans les echantillons de vegetaux et d'insectes et leur identification ont ete menees par l'observation de symptomes au champ, et des analyses DAS-ELISA (double antibody sandwich-enzyme linked immunosorbent assay), nested-PCR (nested polymerase chain reaction) et RFLP (restriction fragment length polymorphism). Les analyses de laboratoire ont montre la presence de phytoplasmes appartenant au : i) groupe 16SrX, sous-groupe A ('Candidatus Phytoplasma mali') dans 23 des 25 echantillons de pommiers, dans 4 groupes sur 18 de Cacopsylla picta (synonyme Cacopsylla costalis) et dans 2 groupes sur 9 de Cacopsylla melanoneura ; ii) groupe 16SrX, sous-groupe C ('Candidatus Phytoplasma pyri') dans 11 des 30 echantillons de poiriers et dans 2 groupes sur 9 de Cacopsylla pyri;iii) groupe 16SrX, sous-groupe B ('Candidatus Phytoplasma prunorum') dans 4 echantillons d'abricotiers, 2 de pechers sur les 42 echantillons d'arbres fruitiers a noyaux et dans 1 groupe sur 14 de Cacopsylla pruni. La presence de differents sous-groupes de Candidatus Phytoplasma mali a ainsi ete prouvee a la fois dans les pommiers et les insectes.

‘Candidatus Phytopalsma mali’ directly manipulates plant physiology and indirectly vector behaviour by attracting its vector Cacopsylla picta to infected plants and thus increasing its spread within the host plant population. In recent years constructing traps with attractive components like β-caryophyllene for the capture of psyllids could greatly reduce the efforts necessary for insect identification. Furthermore, through this monitoring the amount of chemical insecticides can be reduced by detecting the adequate date for spraying. Because the infochemical produced by infected plants is attractive to both sexes of psyllids, it could also be possible to develop mass trapping systems for a sustainable control of these insects. When identified, attractive compounds could be used in traps as lures for monitoring and mass trapping purposes and combined with repellent compounds these chemicals can be used in complex push-and-pull strategies.

As there is no applicable means to cure a phytoplasma-infected fruit tree, insecticide treatments are the first measures to control the spread of fruit tree phytoplasma diseases whenever a vector species is identified. Although it is impossible to eliminate all vectors from the environment, well-managed vector control strategies significantly reduce the chance of an epidemic outbreak of phytoplasma diseases. However, important differences exist between the control of univoltine and polyvoltine psyllid vectors. Highly efficient univoltine vectors, e.g. Cacopsylla picta, the vector of apple proliferation disease, might be present in the orchards in very low abundance. An appropriate and efficient insecticides might miss or might not be homologated in all countries. Control of univoltine vectors is not well studied as it is the case for Cacopsylla pruni, the vector of European stone fruit yellows. On the contrary, polyvoltine pear psyllids, vectors of pear decline, are pests on their own and, therefore, control strategies and efficacies of different insecticides are well studied. The present work, focus on recent progress made in integrated control of pear psyllids.