Using molecular (COI, Cytb, H3, wg, 12S, 16S, and 28S) and morphological data (61 characters of adults and immatures), the phylogenetic relationships of the 20 nominal genera of Liviinae were analysed, and the monophyly of the subfamily was tested relative to the other two subfamilies of Liviidae. The analyses of the molecular, morphological, and combined datasets provided similar results with a strong or moderate support in the molecular and combined analyses for the subfamilies of Liviidae and two clades in Liviinae given tribal rank (Liviini and Paurocephalini stat. rev.). Three of the six previously recognized genera were confirmed as monophyletic (Aphorma, Camarotoscena, and Livia) and three were shown to be polyphyletic: Diclidophlebia s.l. (Diclidophlebia s.s., Haplaphalara stat. rev., Klyveria Burckhardt, Serbina and Malenovský, gen. nov., Melanastera Serbina, Malenovský, Queiroz and Burckhardt, gen. nov. and Woldaia stat. rev.), Paurocephala s.l. (Liella Burckhardt, Serbina and Malenovský, gen. nov. and Paurocephala s.s.), and Syntomoza s.l. (Anomoterga stat. rev. and Syntomoza s.s.). The new generic definitions require 38 new and eight revived combinations, including the transfer of two species to other families. All genera of Liviinae are diagnosed and keys are provided for their identification. A checklist of world Liviinae is supplemented.

Food security is threatened by newly emerging pests with increased invasive potential accelerated through globalization. The Neotropical jumping plant louse Russelliana solanicola Tuthill is currently a localized potato pest and probable vector of plant pathogens. It is an unusually polyphagous species and is widely distributed in and along the Andes. To date, introductions have been detected in eastern Argentina, southern Brazil and Uruguay. Species distribution models (SDMs) and trait comparisons based on contemporary and historical collections are used to estimate the potential spread of R. solanicola worldwide. We also extend our analyses to all described species in the genus Russelliana in order to assess the value of looking beyond pest species to predict pest spread. We investigate the extent to which data on geographical range and environmental niche can be effectively extracted from museum collections for comparative analyses of pest and non-pest species in Russelliana. Our results indicate that R. solanicola has potential for invasion in many parts of the world with suitable environmental conditions that currently have or are anticipated to increase potato cultivation. Large geographical ranges are characteristic of a morphological subgeneric taxon group that includes R. solanicola; this same group also has a larger environmental breadth than other groups within the genus. Ecological modelling using museum collections provides a useful tool for identifying emerging pests and developing integrated pest management programs.

Psyllids are phloem‐feeding insects that can transmit plant pathogens such as phytoplasmas, intracellular bacteria causing numerous plant diseases worldwide. Their microbiomes are essential for insect physiology and may also influence the capacity of vectors to transmit pathogens. Using 16S rRNA gene metabarcoding, we compared the microbiomes of three sympatric psyllid species associated with pear trees in Central Europe. All three species are able to transmit ‘ Candidatus Phytoplasma pyri’, albeit with different efficiencies. Our results revealed potential relationships between insect biology and microbiome composition that varied during psyllid ontogeny and between generations in Cacopsylla pyri and C. pyricola , as well as between localities in C. pyri . In contrast, no variations related to psyllid life cycle and geography were detected in C. pyrisuga . In addition to the primary endosymbiont Carsonella ruddii , we detected another highly abundant endosymbiont (unclassified Enterobacteriaceae). C. pyri and C. pyricola shared the same taxon of Enterobacteriaceae which is related to endosymbionts harboured by other psyllid species from various families. In contrast, C. pyrisuga carried a different Enterobacteriaceae taxon related to the genus Sodalis . Our study provides new insights into host–symbiont interactions in psyllids and highlights the importance of host biology and geography in shaping microbiome structure.

The Neotropical genus Russelliana (Psyllidae: Aphalaroidinae) is revised and its phylogenetic, host-plant and biogeographical relationships are discussed. Twenty-four species are described as new, bringing the number of known species to 43. An identification key is provided for the adults. A phylogenetic analysis of 26 morphological characters resulted in 54 most parsimonious trees. The consensus tree is well resolved at the base but poorly at the crown. Most Russelliana species are monophagous or oligophagous with the exception of R. solanicola which is polyphagous. With eight plant families, the host range of Russelliana is broader than that of other aphalaroidine genera. The hosts for 29 species are confirmed, those for 12 species are suggested based on phylogenetic relationships. The species associated with Asteraceae (4 spp.) and most of the Fabaceae-feeders (12 spp.) form each a monophyletic group, those associated with Verbenaceae (5 spp.) are paraphyletic and those with Solanaceae are polyphyletic (16 spp.). The two species associated with Rosaceae are not closely related. These patterns suggest repeated host shifts. Whether there is cospeciation in some groups cannot be judged as neither psyllid nor host phylogenies are sufficiently resolved. The world psylloid fauna comprises relatively few species associated with Solanaceae. The number of 16 Russelliana species with confirmed or likely solanaceous hosts is, therefore, surprising and important in view of the potential pest status of some Russelliana spp. The genus is restricted to temperate and subtropical South America (Argentina, Bolivia, Southern Brazil, Chile, Peru and Uruguay). Most species are known from the Western Andean part of the continent. Only four species are currently known from Eastern South America. The cladogram suggests that geographical vicariance may account for at least part of the observed species richness, as five vicariant events were detected for Russelliana. A better resolution of the cladogram may reveal more cases of geographical vicariance.

Wolbachiais one of the most abundant intracellular symbionts of arthropods and has profound effects on host biology.Wolbachiatransmission and host phenotypes often depend on its density within the host, which can be affected by multiple biotic and abiotic factors. However, very few studies measuredWolbachiadensity in natural host populations. Here, we describeWolbachiain the pear psyllidCacopsylla pyrifrom three populations in the Czech Republic. Using phylogenetic analyses based onwspand multilocus sequence typing genes, we demonstrate thatC. pyriharbours three newWolbachiastrains from supergroup B. A fourthWolbachiastrain from supergroup A was also detected in parasitised immatures ofC. pyri, but likely came from a hymenopteran parasitoid. To obtain insights into naturalWolbachiainfection dynamics, we quantifiedWolbachiain psyllid individuals from the locality with the highest prevalence across an entire year, spanning several seasonal generations of the host. All tested females were infected andWolbachiadensity remained stable across the entire period, suggesting a highly efficient vertical transmission and little influence from the environment and different host generations. In contrast, we observed a tendency towards reducedWolbachiadensity in males which may suggest sex-related differences inWolbachia-psyllid interactions.

The Neotropical jumping plant-louse Russelliana solanicola Tuthill is a potato pest and a probable vector of plant pathogens. Populations morphologically similar to those found on potatoes have been collected on plants of at least ten different families, four of which have been confirmed as hosts by the presence of immatures. This suggests that R. solanicola is either a single polyphagous species or a complex of closely related, monophagous species (host races/cryptic species). Results of our analyses of multiple morphometric characters show for both sexes a grouping of the populations of R. solanicola and a clear separation of the latter from other Russelliana species. On the other hand, within R. solanicola, there is an overlap of populations from different host-plants as well as from different geographical regions. The results of the present study strongly suggest that R. solanicola is a single, polyphagous species and the known distribution indicates that it is native to the Andes. It is likely that R. solanicola has been introduced into eastern Argentina, Brazil and Uruguay. The polyphagy together with the ability to disperse and transmit plant pathogens potentially make this species an economically important pest of potato and other crop species.