Orientus Ishidae Research Articles

Gone-wild grapevines in forests host phytoplasma genotypes linked to grapevine’s flavescence dorée epidemics in cultivated vineyards and competent vectors

Abstract“Flavescence dorée” (FD) is a quarantine grapevine disease associated with FD phytoplasmas (FDp). In Switzerland, FD was identified in 2004 in the southernmost part of Canton Ticino (TI) and then rapidly propagated throughout the entire regional winegrowing area despite the mandatory control measures. The reported widespread distribution of gone-wild grapevines (GWGV) in TI raised the hypothesis of a potential role of GWGV as an FDp reservoir and as a habitat for FDp vectors. To test this assumption, GWGV and FDp vectors were sampled in 13 plots to attest their infection status and compare the FDp genetic profiles. The primary (Scaphoideus titanus) and best-candidate alternative (Orientus ishidae) vectors were collected throughout the season and were found in moderate to high abundance in all the study area. The infection rate of both GWGV and S. titanus followed the historical gradient of S. titanus arrival and dispersal in TI with a clear geographic distinction between the southern and northern part of TI. Interestingly, the rate measured for S. titanus was similar to that observed in highly FD-infested cultivated vineyards. Moreover, the genetic profiles of the infected GWGV and S. titanus samples were identical to those commonly observed in cultivated vineyards (map M54). Importantly, four specimens of O. ishidae were also found harboring the same genotype. This study emphasizes the importance of GWGV (and abandoned vineyards) and alternative vectors for the FD epidemics in FD-infested regions, as well as a potential origin for FD outbreaks in areas currently designated as FDp-free.

First detection of ‘Candidatus Phytoplasma ulmi’ in Switzerland and in Orientus ishidae Matsumura, 1902

‘Candidatus Phytoplasma ulmi’ (Ca. P. ulmi) belongs to the ribosomal subgroup 16SrV-A and is associated with dieback, shoot proliferation and yellows disease on various Ulmus spp. Other plant species, such as Carpinus betulus and Prunus spp. have also been reported infected by the same pathogen. In 2021, in the frame of research activities focused on grapevine’s Flavescence dorée (FD), one specimen of Orientus ishidae - an East Palearctic leafhopper that was identified as an alternative vector of FD phytoplasmas - was found harboring Ca. P. ulmi in southern Switzerland. No phytoplasmas were detected in plant samples taken in the same location. Orientus ishidae has already been reported to be able to acquire diverse phytoplasmas associated with other plant diseases, such as Peach X-disease. This is the first report of Ca. P. ulmi in Switzerland, as well as in O. ishidae. Ca. P. ulmi may potentially be present in the wild compartment of the Swiss Pre-alpine and Alpine range, but no dedicated survey has so far been conducted. In the case of O. ishidae, this finding highlights the broad affinity of such a species for the acquisition of several phytoplasmas. This calls for a further investigation regarding its potential role as a vector on various pathosystems of agronomic importance.

New host-parasitoid association and the Trojan horse strategy adopted by the cuckoo wasp Elampus bidens with two vectors of Flavescence Dorée: Scaphoideus titanus and Orientus ishidae

New host-parasitoid association and the Trojan horse strategy adopted by the cuckoo wasp Elampus bidens with two vectors of Flavescence Dorée: Scaphoideus titanus and Orientus ishidae

Gone‐wild grapevines in forests may act as a potential habitat for ‘Flavescence dorée’ phytoplasma vectors and inoculum

Abstract‘Flavescence dorée’ (FD) is a quarantine grapevine disease associated with FD phytoplasmas (FDp). In Switzerland, FD was first reported in 2004 in the southern part of the Canton Ticino, from where, within a few years, it spread to nearly the entire vineyard area of the Southern Alps, despite the mandatory control measures. The aim of this study was to assess the possible role of gone‐wild grapevines (GWGVs) in forests resulting from early abandoned vineyards as a habitat for the main FDp vector, Scaphoideus titanus, and for the best alternative vector candidate, Orientus ishidae, as well as an FDp inoculum reservoir in Southern Switzerland. Leaf samples were collected in 20 plots and tested for the presence of FDp. Moreover, fifteen of these plots were monitored with yellow sticky traps to determine the presence and infection status of insect vectors. Finally, a hatching experiment under controlled conditions was conducted to investigate the possible oviposition activity by FDp vectors, using wood collected from GWGVs present in 11 forest sites in the surroundings of cultivated vineyards. GWGVs in forests were confirmed to act as an FDp reservoir and to represent a suitable habitat for FDp vectors (in particular, for S. titanus). Abandoned vineyards should be included in the FD management strategy and their systematic rogueing should be applied as soon as possible and in particular before the transition from vineyard to forest occurs, in order to avoid the survival of S. titanus and the establishment of inoculum in uncontrolled landscape compartments.

Epidemiology of flavescence dorée and hazelnut decline in Slovenia: geographical distribution and genetic diversity of the associated 16SrV phytoplasmas.

Flavescence dorée (FD) phytoplasma from 16SrV-C and -D subgroups cause severe damage to grapevines throughout Europe. This phytoplasma is transmitted from grapevine to grapevine by the sap-sucking leafhopper Scaphoideus titanus. European black alder and clematis serve as perennial plant reservoirs for 16SrV-C phytoplasma strains, and their host range has recently been extended to hazelnuts. In Slovenia, hazelnut orchards are declining due to 16SrV phytoplasma infections, where large populations of the non-autochthonous leafhopper Orientus ishidae have been observed. To better characterise the phytoplasma-induced decline of hazelnut and possible transmission fluxes between these orchards and grapevine, genetic diversity of 16SrV phytoplasmas in grapevine, hazelnut and leafhoppers was monitored from 2017 to 2022. The nucleotide sequence analysis was based on the map gene. The most prevalent map genotype in grapevine in all wine-growing regions of Slovenia was M54, which accounted for 84% of the 176 grapevines tested. Besides M54, other epidemic genotypes with lower frequency were M38 (6%), M51 (3%), M50 (2%) and M122 (1%). M38, M50 and M122 were also detected in infected cultivated hazelnuts and in specimens of O. ishidae leafhopper caught in declining hazelnut orchards. It suggests that this polyphagous vector could be responsible for phytoplasma infection in hazelnut orchards and possibly for some phytoplasma exchanges between hazelnuts and grapevine. We hereby describe new genotypes: M158 in grapevine as well as four never reported genotypes M159 to M162 in hazelnut. Of these four genotypes in hazelnut, one (M160) was also detected in O. ishidae. Analysis of additional genes of the new genotypes allowed us to assign them to the VmpA-III cluster, which corresponds to the 16SrV-C strains previously shown to be compatible with S. titanus transmission.

Orientus ishidae (Hemiptera: Cicadellidae): Biology, Direct Damage and Preliminary Studies on Apple Proliferation Infection in Apple Orchard.

The mosaic leafhopper, Orientus ishidae (Matsumura), is an Asian species widespread in Europe that can cause leaf damage in wild trees and transmit disease phytoplasmas to grapevines. Following an O. ishidae outbreak reported in 2019 in an apple orchard in northern Italy, the biology and damage caused by this species to apples were investigated during 2020 and 2021. Our studies included observations on the O. ishidae life cycle, leaf symptoms associated to its trophic activity, and its capability to acquire "Candidatus Phytoplasma mali," a causal agent of Apple Proliferation (AP). The results indicate that O. ishidae can complete the life cycle on apple trees. Nymphs emerged between May and June, and adults were present from early July to late October, with the peak of flight between July and early August. Semi-field observations allowed for an accurate description of leaf symptoms that appeared as a distinct yellowing after a one-day exposure. In field experiments, 23% of the leaves were found damaged. In addition, 16-18% of the collected leafhoppers were found carrying AP phytoplasma. We conclude that O. ishidae has the potential to be a new apple tree pest. However, further studies are required to better understand the economic impact of the infestations.

Alnus glutinosa and Orientus ishidae (Matsumura, 1902) share phytoplasma genotypes linked to the ‘Flavescence dorée’ epidemics

AbstractFlavescence dorée (FD) is a grapevine disease caused by associated phytoplasmas (FDp) which are epidemically spread by their main vector Scaphoideus titanus. The possible roles of alternative and secondary FDp plant hosts and vectors have gained interest in terms of better understanding of the FDp ecology and epidemiology. The findings of a survey conducted in the surroundings of three vineyards in the southern Swiss Alps aimed at studying the possible epidemiological role of the FDp secondary vector Orientus ishidae and the FDp host plant Alnus glutinosa are reported. This work demonstrates that O. ishidae is able to complete its biological cycle on A. glutinosa and to acquire FDp and 16SrV phytoplasmas very efficiently with an infection rate of 69% for the nymphal instars and 85% for the imagoes. A high prevalence of the map genotype M50 (map type FD1), which is included in the S. titanus—grapevine epidemiological cycle, was found in O. ishidae and A. glutinosa. Additionally, M12 (map type FD3), M44 and M47 were also sporadically detected. Surprisingly, the grapevines tested during this work were all infected by M54 (map type FD2) only, while the few S. titanus caught in the vineyard canopy were all FDp free. In conclusion, the occurrence of infected common alder stands and O. ishidae nearby vineyards do not seem to play a prominent role in FD epidemics in southern Switzerland. Nevertheless, wild vegetation acts as a reservoir of the FDp inoculum, which may locally trigger a FD emergence if S. titanus populations are established inside vineyards.

Palaearctic Egg Parasitoids Interaction to Three Grapevine Exotic Pests in Northwestern Italy: A New Association Involving Metcalfa pruinosa.

Simple SummaryScaphoideus titanus, Orientus ishidae and Metcalfa pruinosa are exotic hoppers considered as the most important pest for Italian viticulture. They are usually controlled by insecticides in industrial viticulture. These pest populations tend to increase in uncultivated areas within the vineyard agroecosystem where the pesticides are forbidden. Therefore, we investigated the presence of egg parasitoids, as possible biocontrol agents, and the interaction with other parasitoids in these environments. No specimen emerged from the eggs of the first two leafhoppers, while many specimens identified as Oligosita collina group emerged from the eggs of the planthopper M. pruinosa, which represents a new association. We consequently evaluated its parasitization rate, which showed a very high value, in different Piedmontese wine growing areas. The preliminary study pointed out a higher percentage of the egg parasitoid compared to the currently used biocontrol agent Neodryinus typhlocybae. The identification of an oophagous able to adapt to this flatid open up new perspective on M. pruinosa control.The most important exotic leafhopper pests currently affecting the Italian vineyards are the leafhoppers Scaphoideus titanus, Orientus ishidae and the planthopper Metcalfa pruinosa. Their highest population density is detected in the uncultivated areas with wild grapevines. Should these habitats be considered only a problem or a potential resource for Palearctic entomophagy of these three exotic pests? The aim of this work was to study the biotopes and biocoenosis present in the Piedmontese vineyard agroecosystem, evaluating the parasitization rate and other crucial aspects for a possible application in biological control. Several specimens of egg-parasitoid wasps were obtained from filed-collected two-year-old grapevine canes. The most prevalent one belonged to the Oligosita collina group (Trichogrammatidae) emerged only from M. pruinosa eggs with a parasitization rate of over 40%. The new association is the first report of such a high level of parasitization on the flatid planthopper. The parasitization rate mainly relied on the host egg density and the abundance of plants suitable for the oviposition. A second parasitoid generation on the overwintering eggs is discussed, as well as other hypothesis. Furthermore, the parasitization rate was higher than the one showed by the dryinid Neodryinus typhlocybae, the control agent introduced in Italy under the biological control strategy, highlighting a possible implication in this biocoenosis. We assume that the egg parasitoid adaptation may contribute to M. pruinosa control.

New records and updates on alien Auchenorrhyncha species in Serbia

During a 2019 survey of the Auchenorrhyncha fauna in Serbia, three alien species were recorded for the first time: a leafhopper species of Asian origin Orientus ishidae (Cicadellidae, Deltocephalinae) and two North American species, Acanalonia conica (Acanaloniidae) and Erasmoneura vulnerata (Cicadellidae, Typhlocybinae). Besides these first findings, the presence of the leafhopper Phlogotettix cyclops (Cicadellidae, Deltocephalinae) was confirmed in Serbia after its initial record more than a century ago. Other allochthonous species already known to be present in local entomofauna were also found: Japananus hyalinus (Cicadellidae, Deltocephalinae), Scaphoideus titanus (Cicadellidae, Typhlocybinae), Stictocephala bisonia (Membracidae) and Metcalfa pruinosa (Flatidae). The newly detected Auchenorrhyncha species in Serbia, O. ishidae, A. conica and E. vulnerata, as well as Ph. cyclops, are recognized as either tentative or true grapevine pests in Europe that cause physical damage or induce phytoplasma-borne diseases. Our findings reveal a potential phytosanitary risk that can emerge in Serbian vineyards in upcoming years and support refocused research of Auchenorrhyncha diversity in natural habitats, rather than in agroecosystems and their immediate surroundings.

New insights into the emergence of the grapevine "flavescence dorée" epidemics in Europe

A survey of genetic diversity of “flavescence doree” (FD)-related phytoplasmas in grapevines, alders and clematis as well as alder-feeding leafhoppers was conducted in France, Hungary, Germany, Italy and Serbia. Genotyping was based on the housekeeping gene map and on the vmp genes encoding surface variable membrane proteins. Transmission assays of the phytoplasmas were performed with alder and/or grapevine-feeding leafhoppers. The study demonstrated that European alders constitute an original reservoir of FD phytoplasma by hosting a high diversity of FD-related phytoplasma genotypes, also present in non viticultural areas. The alder phytoplasmas grouping in Vmp-I cluster were transmitted by the Macropsinae O. alni, but were not compatible with the FD phytoplasma vector on grapevine the Deltocephalinae Scaphoideus titanus. The alder phytoplasmas in Vmp-II and-III clusters were transmitted by the Deltocephalinae Allygus spp. and Orientus ishidae. Such pre-existing phytoplasmas were compatible with S. titanus transmissibility and can be responsible for the emergence of FD phytoplasma epidemics in grapevine. VmpA proteins of cluster II better adhered to Euscelidius variegatus and S. titanus insect cells and midguts than those of cluster I. Such adhesins might play a key role in the adaptation to new vectors.

Potential role of Orientus ishidae in the “flavescence dorée” epidemics in Ticino, Switzerland

The constant, even if low, presence of grapevine “flavescence doree” (FD) in the vineyards of Ticino, Switzerland, challenged the stakeholders to investigate for other players involved in the FD dynamics. This study was aimed to explore the impact that the exotic leafhopper Orientus ishidae may have on FD epidemics in Ticino by monitoring its population density and level of infection with 16SrV group phytoplasmas. In 2018, 283 leafhoppers were collected from three FD infected areas, both from the vineyards and the surrounding landscape. Spatial density maps showed that the captures occurred mostly in the landscape, with a clear clustered distribution among the traps. Molecular analyses revealed a high infection percentage of O. ishidae samples in the three investigated plots, both inside and outside the vineyards.

Molecular Diversity of Phytoplasmas Associated with Grapevine Yellows Disease in North-Eastern Italy.

A 3-year survey was conducted in Northern Italy to verify the presence and diversity of phytoplasmas in selected vineyards showing symptoms of severe yellows. Symptomatic and asymptomatic grapevines were sampled, and insects were collected using yellow sticky traps. The phytoplasmas detected in grapevine samples were different according to the years: "flavescence dorée" (16SrV-C/D) was detected together with other phytoplasmas such as 16SrXII-A ('Candidatus Phytoplasma solani'-related, bois noir), 16SrI-B ('Ca. P. asteris'-related, aster yellows), 16SrX-B ('Ca. P. prunorum'-related, European stone fruit yellows), and 16SrV-A ('Ca. P. ulmi'-related, elm yellows). Moreover, phytoplasmas belonging to 16SrVII-A ('Ca. P. fraxini'-related) and 16SrVI ('Ca. P. trifolii'-related) subgroups were also identified. Identification of phytoplasmas was also carried out from insects and showed the presence of some of these phytoplasmas in Scaphoideus titanus and Orientus ishidae: 16SrXII-A, 16SrVII, and 16SrVI phytoplasmas were detected in specimens of both species, while 16SrXII-A and 16SrI-B phytoplasma strains were identified in Orientus ishidae and Hyalesthes obsoletus, and 16SrX-B in S. titanus. Direct sequencing of selected amplicons obtained from 16S rRNA, rp, and tuf genes from grapevine and insect samples confirmed the phytoplasma identification. The 16SrVII-A and 16SrVI phytoplasmas were never detected before in grapevine, S. titanus and Orientus ishidae in Europe and their epidemiological importance is being monitored.

Dual \u201cBacterial-Fungal\u201d Symbiosis in Deltocephalinae Leafhoppers (Insecta, Hemiptera, Cicadomorpha: Cicadellidae)

The symbiotic systems (types of symbionts, their distribution in the host insect body, and their transovarial transmission between generations) of four Deltocephalinae leafhoppers: Fieberiella septentrionalis, Graphocraerus ventralis, Orientus ishidae, and Cicadula quadrinotata have been examined by means of histological, ultrastructural, and molecular techniques. In all four species, two types of symbionts are present: bacterium Sulcia (phylum Bacteroidetes) and yeast-like symbionts closely related to the entomopathogenic fungi (phylum Ascomycota, class Sordariomycetes). Sulcia bacteria are always harbored in giant bacteriocytes, which are grouped into large organs termed “bacteriomes.” In F. septentrionalis, G. ventralis, and O. ishidae, numerous yeast-like microorganisms are localized in cells of the fat body, whereas in C. quadrinotata, they occupy the cells of midgut epithelium in large number. Additionally, in C. quadrinotata, a small amount of yeast-like microorganisms occurs intracellularly in the fat body cells and, extracellularly, in the hemolymph. Sulcia bacteria in F. septentrionalis, G. ventralis, O. ishidae, and C. quadrinotata, and the yeast-like symbionts residing in the fat body of F. septentrionalis, G. ventralis, and O. ishidae are transovarially transmitted; i.e., they infect the ovarioles which constitute the ovaries.

The first record of a potential pest Orientus ishidae (Matsumura, 1902) (Hemiptera: Cicadellidae) in Poland

Abstract This study provides the first data on the occurrence of the mosaic leafhopper Orientus ishidae (Matsumura, 1902) (Hemiptera: Cicadellidae) in Poland. This species is native to Southeast Asia, adventive in Europe and feeds on cultivated plants. Orientus ishidae is a well-known carrier of Grapevine flavescence doree phytoplasma which causes the grapevine yellows disease. Symptoms of phytoplasma diseases of grapevine include deformations, leaf chlorosis and withering of plants. The appearance of this species in Poland might be caused by observed climate variations and insufficient plant health controls in the international trade of plants.

New insights on Flavescence dorée phytoplasma ecology in the vineyard agro‐ecosystem in southern Switzerland

AbstractPhytoplasmas associated with Flavescence dorée (FDp) grapevine disease are quarantine pathogens controlled through mandatory measures including the prompt eradication and destruction of diseased plants, and the insecticide treatments against the insect vector, the ampelophagous leafhopper Scaphoideus titanus. In the present study, a multidisciplinary approach has been applied to investigate the FDp ecological cycle in a test vineyard agro‐ecosystem in Canton Ticino, south Switzerland. Despite the scarce population density of S. titanus, a regular trend of new infections (3.4% of the total vines) through the years was observed. The leafhopper Orientus ishidae was found as the most abundant among the captured insect species known as phytoplasma vectors (245 out of 315 specimens). The population of O. ishidae was evidenced prevalently (167 specimens) in the south‐western side of the vineyard and within the neighbouring forest constituted mainly by hazel (Corylus avellana) and willow (Salix spp.). These plant species were found infected by FDp related strains (30% of analysed trees) for the first time in this study. Interestingly, O. ishidae was found to harbour FDp related strains in high percentage (26% of the analysed pools). In addition, 16SrV phytoplasma group was detected for the first time in the insect Hyalesthes obsoletus and a FDp related strain in Thamnotettix dilutior, present in low populations within the test vineyard. Molecular characterisation and phylogenetic analyses of methionine aminopeptidase (map) gene sequences of FDp and related strains, here identified, revealed the great prevalence of the map‐type FD2 in grapevines (97%) and in O. ishidae pools (72%). Such a map‐type was found also in hazel and in T. dilutior, but not in S. titanus. Moreover, map‐types FD1 and FD3 were identified for the first time in Switzerland in several host plants and phytoplasma vectors, including grapevine (FD1), S. titanus (FD1) and O. ishidae (FD1 and FD3). Based on the data obtained in this study, it is reasonable to hypothesise that the ecological cycle of FDp could be related not exclusively to the grapevine‐specific feeding diet of S. titanus, but it could include other insect vector(s) and/or plant host(s). Further studies will be needed to prove the role of O. ishidae as vector able to transmit FDp from wild plants (e.g. hazel) to grapevine.

First detection of the mosaic leafhopper, Orientus ishidae, in northern Italian vineyards infected by the flavescence dorée phytoplasma

Orientus ishidae Matsumura 1902 [ Hemiptera, Auchenorrhyncha, Cicadellidae ], known as the mosaic leafhopper, was recently found by Lombardy Plant Health Service technicians (Servizio Fitosanitario Regione Lombardia) in northern Italian…

The first detection of a phytoplasma from the 16SrV (Elm yellows) group in the mosaic leafhopper Orientus ishidae

In 2009 in Slovenia, an uncultivable cell-wall-less pathogenic bacterium of the class Mollicutes - a phytoplasma belonging to the 16SrV (Elm yellows) group was found in the mosaic leafhopper ( Orientus ishidae ) [Hemiptera, Cicadomorpha:…

Leaf hoppers (Hemiptera: Cicadellidae) Associated with Ornamental Honey Locust: Seasonal History, Habits, and Descriptions of Eggs and Fifth Instars

The leaf hopper fauna of ornamental honey locust, Gleditsia triacanthos L., was studied in south-central Pennsylvania. Detailed life history information was obtained on Macropsis fumipennis (Gillette & Baker) and Stragania apicalis (Osborn & Ball), two species restricted to honey locust, and on Orientus ishidae (Matsumura), known to feed on several hardwoods. Notes also are presented for S. alabamensis (Baker) and Empoasca fabae (Harris), the potato leafhopper. Adults of three Erythroneura species also were collected. The eggs and fifth instars of M. fumipennis, S. apicalis, and O. ishidae are described and illustrated. Overwintering eggs of M. fumipennis hatched shortly after leaf flush began in April. Adults first were observed in mid-May and disappeared by mid- to late July. Nymphs of S. apicalis first appeared in early to mid-May, and adults emerged in late June. Nymphs of these two species fed mostly on petioles, petiolules, and rachises rather than on leaflets. Eggs of O. ishidae hatched in early June, and adults first appeared in early July; nymphal feeding caused a yellowing of leaflets. Adults and nymphs of E. fabae appeared almost simultaneously on the trees in early to mid-June and fed on the second flush of new growth. Occasional adults and nymphs of S. alabamensis also were collected, mainly on native trees. Leafhoppers (unlike the mirid Diaphnocoris chlorionis [Say]) do not seriously injure honey locust in Pennsylvania.

Note on Two Species of Leafhoppers (Homoptera: Cicadellidae) New to Canada

Three specimens of a species of leafhopper new to the Niagara Peninsula were collected during 1956 along the wooded bank of Niagara River below Queenston, Ontario; they were identified by Mrs. C. J. Williams, Entomology Division, Ottawa, as Orientus ishidae (Mat.) and are in the Canadian National Collection. According to Oman (1949), this is an introduced Japanese species which lives on willow and is widely distributed. Presumably Oman's statement is based on collections made in the United States as Mrs. Williams stated (in litt.) that this was the first record from Canada.