Flavescence dorée (FD) is a European quarantine grapevine disease transmitted by the Deltocephalinae leafhopper Scaphoideus titanus. Whereas this vector had been introduced from North America, the possible European origin of FD phytoplasma needed to be challenged and correlated with ecological and genetic drivers of FD emergence. For that purpose, a survey of genetic diversity of these phytoplasmas in grapevines, S. titanus, black alders, alder leafhoppers and clematis were conducted in five European countries. Out of 132 map genotypes, only 11 were associated to FD outbreaks, three were detected in clematis, whereas 127 were detected in alder trees, alder leafhoppers or in grapevines out of FD outbreaks. Most of the alder trees were found infected, including 8% with FD genotypes M6, M38 and M50, also present in alders neighboring FD-free vineyards and vineyard-free areas. The Macropsinae Oncopsis alni could transmit genotypes unable to achieve transmission by S. titanus, while the Deltocephalinae Allygus spp. and Orientus ishidae transmitted M38 and M50 that proved to be compatible with S. titanus. Variability of vmpA and vmpB adhesin-like genes clearly discriminated 3 genetic clusters. Cluster Vmp-I grouped genotypes only transmitted by O. alni, while clusters Vmp-II and -III grouped genotypes transmitted by Deltocephalinae leafhoppers. Interestingly, adhesin repeated domains evolved independently in cluster Vmp-I, whereas in clusters Vmp-II and–III showed recent duplications. Latex beads coated with various ratio of VmpA of clusters II and I, showed that cluster II VmpA promoted enhanced adhesion to the Deltocephalinae Euscelidius variegatus epithelial cells and were better retained in both E. variegatus and S. titanus midguts. Our data demonstrate that most FD phytoplasmas are endemic to European alders. Their emergence as grapevine epidemic pathogens appeared restricted to some genetic variants pre-existing in alders, whose compatibility to S. titanus correlates with different vmp gene sequences and VmpA binding properties. Since the first outbreaks, Flavescence dorée epidemics had been associated to the introduction of the North American leafhopper vector Scaphoideus titanus. We hereby show that the associated phytoplasma originated from European alders and that epidemics in grapevine are restricted to some phytoplasma genetic variants pre-existing in this wild asymptomatic plant host. The compatibility of this phytoplasma to the introduced S. titanus insect vector resulted from the adaptation of phytoplasma variable membrane proteins Vmps to leafhoppers of the same subfamily living on alders. Vmps organization is similar to adhesion related proteins (ARP) and seems to allow the duplication of pre-adapted repeated domains. This suggests a key role of the Vmp adhesins in the life-style of phytoplasmas infecting woody hosts that rely on the adaptation to new insect vectors to expand their plant-host range.

A phylogenetic analysis of the species belonging to the weevil genus Rhinusa Stephens, 1829 (Coleoptera: Curculionidae: Curculioninae: Mecinini) was carried out. Rhinusa weevils feed on plants of the closely related families Scrophulariaceae and Plantaginaceae. Based on a cladistic analysis of six outgroup and 33 ingroup taxa, and 39 adult morphological and 8 ecological characters, eight well supported species groups and two monobasic groups belonging to three separate and more inclusive assemblages were recognized. The first assemblage (A) includes nine species belonging to two groups (R. bipustulata and R. tetra groups), whereas the second and third assemblages (B and C) include a total of 14 species belonging to two groups (R. antirrhini and R. linariae groups) and six groups (R. pilosa, R. herbarum, R. neta, R. vestita, R. mauritii and R. melas groups), respectively. Two of the three main assemblages (A and B) are well supported as monophyletic entities, whereas the third assemblage (C) has weak support contingent in part upon the exclusion of host plant associations. Assemblage A includes all species living on species of Scrophulariaceae, with two groups occurring on two closely related plant genera, Scrophularia (R. bipustulata group) and Verbascum (R. tetra group), respectively. The other two assemblages include species living exclusively on species of the family Plantaginaceae, tribe Antirrhineae. These patterns suggest a well conserved and phylogenetically congruent association among the weevils and their hosts. Optimizing host plant preferences onto the morphological phylogeny indicates that feeding on Plantaginaceae was the plesiomorphic condition for the genus Rhinusa. In general there are no strict relationships between groups of weevils and their specific feeding habits; however, species of the R. antirrhini group are all feeding on seed capsules. In contrast, in other groups the larvae of closely related species display significant variations in host plant parasitism. Some species of the R. tetra group feed on seed capsules whereas others are stem borers. In turn, certain species of the R. neta group feed on seed capsules yet others are inquilines of gall forming species of Rhinusa. The latter habit is present in multiple convergent groups such as the R. linariae and R. pilosa groups.

The relationship between the generaCleopomiarusandMiarusof Mecinini (Curculionidae, Curculioninae) was tested on the basis of morphological characters from the immature stages. The mature larvae of fiveCleopomiarusspecies (C.distinctus(Boheman, 1845),C.graminis(Gyllenhal, 1813),C.longirostris(Gyllenhal, 1838),C.medius(Desbrochers des Loges, 1893), andC.meridionalis(H. Brisout de Barneville, 1863)), threeMiarusspecies (M.abnormisSolari, 1947,M.ajugae(Herbst, 1795), andM.campanulae(Linnaeus, 1767)), and the pupae of fourCleopomiarusspecies (C.distinctus,C.graminis,C.longirostris, andC.medius) and twoMiarusspecies (M.abnormisandM.ajugae) are described in detail for the first time. To confirm the taxonomic identification of some larvae, DNA COI barcode was obtained and compared with those of adults. The immature stages of the species herein studied were compared with those known from other genera in tribe Mecinini. It is suggested thatMiarusandCleopomiarusmay be monophyletic based on several shared distinctive characters. Larvae ofMiarushave a characteristic maxillary mala with six finger-likedmsof two sizes (one or twodmsvery long and the rest of medium length), this feature being apparently unique among weevils. Other genus-specific character states are observed in the pupae, such as the length of setae on the head, rostrum and pronotum, including the number ofrson the rostrum,dson pronotum, and finally the shape of the urogomphi. A key to the described larvae and pupae were respectively presented. New biological and distributional data on some species are reported.