Development, Spatial Distribution, and Presence on Grapevine of Nymphs of Orientus ishidae (Hemiptera: Cicadellidae), a New Vector of Flavescence Dorée Phytoplasmas

Abstract

Orientus ishidae (Matsumura) (subfamily Deltocephalinae) is an Asian species now widespread in Europe, and a vector of 16SrV phytoplasmas agents of grapevine Flavescence dorée (FDP). Embryonic and post-embryonic development, spatial distribution, and relationships with grapevine of nymphs were studied under field and laboratory conditions. Egg-hatching dynamics and post-embryonic development of nymphs were studied by collecting grapevine wood from managed and unmanaged vineyards (including bot European Vitis vinifera L., and wild American rootstocks) and storing it inside rearing cages at T = 21–23°C. Field sampling of nymphs were made on both grapevine and two elective host plants of O. ishidae: hazelnut and hornbeam. Taylor’s Power Law was applied to assess the aggregation coefficient of early- (first and second) and late- (third to fifth) life instars on leaves and shoots of host plants. More nymphs were obtained from wood collected in unmanaged rather than managed vineyards. Under lab conditions, the embryonic development lasted 34–48 d, whereas the whole post-embryonic development averaged 27 d. Under field conditions, early instars peaked at the end of May, and late instars peaked 2–4 wk later. The aggregation patterns decreased from early to late instars, and from leaves to shoots. Very few nymphs were observed on unmanaged grapevine, either European or American, and none on managed European grapevine. Some behavioral and FDP epidemiological consequences of the results obtained are discussed.

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

“…The obtained results show that in southern Switzerland, common alders are capable of hosting all the main developmental stages of O. ishidae (nymphal instars and imagoes). The particular abundance of L1‐2 nymphal instars and their widespread presence on the surveyed A. glutinosa trees suggests that O. ishidae females may also lay eggs in the bark of common alders, as already demonstrated for other plant species including grapevine (Lessio et al., 2019). This is further corroborated by the fact that L1‐2 nymphal instars were found on common alder branches that were not in the proximity of any other known host plant species of O. ishidae, such as hazelnut or willow (Hamilton, 1985; Mehle et al., 2019).…”

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

“…As far as O. ishidae is concerned, it is worthwhile to notice that fewer eggs of this leafhopper are found compared to the other two pests. Besides, it is known that O. ishidae lays eggs on grapevine in considerably lower number compared to other plants [17], and the grapevine was the most abundant species plant in the vineyard agroecosystem. Therefore, we cannot state with certainty that no egg parasitoids were able to adapt on this leafhopper.…”

“…Adults live on different host plants, such as hazelnut, hornbeam, willow, and others, often present in the surrounding of the vineyards [6]. It is highly polyphagous and can lay eggs on grapevines even if in the nymphs, which can be found from the middle of May up to the middle of July, feed on other plants rather than grapevine, and adults emerge from mid-May until mid-September [17].…”

“…The highest population density of these three species can be detected in the ecological corridors formed by uncultivated areas or woods with wild grapevine, representing a source of re-infestation flows [4,17,18]. In such environments, indeed, insecticides are not allowed since they would have serious negative repercussions on the present biocoenosis.…”

Commodity risk assessment of Corylus avellana and Corylus colurna plants from Serbia

“…Its eggs can be found on Vitis spp. However, the insect does not move frequently to grapevine and is therefore considered only a very occasional vector of FDp (Jermini et al, 2019;Lessio et al, 2019). Nevertheless, O. ishidae has been associated with Corylus avellana and FDp by Casati et al (2017) in Switzerland.…”