Potential Virus Vectors Research Articles

Results of monitoring winged aphids (Hemiptera: Aphididae) on potato plantations in the conditions of the Northern region of Russia

The studies were carried out in the conditions of the northern part of the Arkhangelsk region in the period 2017-2021. The purpose of the research is to determine the abundance and species composition during the annual monitoring of the flight of winged aphids on potato plantations, to establish patterns of insect migration. To catch winged individuals, yellow water traps were used, installed along the perimeter of the field at the beginning of the potato germination phase. The last extraction of the catch was carried out after the desiccation of the potato tops. As a result of the monitoring, 22 species of winged aphids were identified. Of the total number, direct and potential vectors of viruses are represented by 6 species ‒ Acyrthosiphum pisum Harr., Aphis fabae Scop., Aphis nasturtii Kalt., Aulacorthum solani Kalt., Hyperomyzus lactucae L., Rhopalosiphum padi L., their share in the abundance structure ranged from 69.8 to 91.7 %. From the group of aphids-carriers of viruses, 5 species annually migrate to plantings: A. corni F., A. fabae Scop., A. nasturtii Kalt., A. solani Kalt., R. padi L. The total number of winged aphids ranged from 61 individuals in 2020 to 107 individuals in 2018, and in 2021 there was an outbreak of mass reproduction R. padi L. and A. fabae Scop., which increased the total number of captured winged aphids to 1778 individuals. In the period from 2017 to 2020, the prevalence of virus vectors corresponded to a low value (16-27 individuals per 1 water trap), in 2021, against the background of an outbreak of mass reproduction, the prevalence of virus vectors increased to an average value (445 winged individuals per 1 water trap during the growing season). The accumulation of a large migratory potential of aphids occurs under favorable weather conditions in the winter and spring periods, and also, if possible, feed on the primary food plant for a long time. If the host plant is unsuitable for feeding, aphids migrate in search of food, as a result of which their number decreases.

A first Canadian and three new Québec records of Cicadellidae (Hemiptera) in grapevine (Vitaceae): potential virus vectors

AbstractA comprehensive biovigilance programme was undertaken in 2018 to monitor potential insect vectors of viruses of grapevines (Vitis vinifera; Vitaceae) in two vineyards in Québec. Two hundred seventy-four insects were collected using yellow sticky traps and sweeping nets. Collected specimens were first classified into orders, with special attention given to the Hemiptera order, which is the main group of virus vectors. Hemipteran pests were identified to species. Among these specimens, one adult ofRossmoneura tectaMcAtee (Hemiptera: Cicadellidae) was identified, the first report of this species in Canada.Empoasca vinculaDeLong,Erythroneura acuticephalaRobinson, andErythroneura cymbiumMcAtee, three other species belonging to the same family and previously reported in other Canadian provinces, were also identified for the first time in Québec. Further investigations are being undertaken to test the ability of these species to transmit grapevine viruses.

МОНИТОРИНГ ЭНТОМОКОМПЛЕКСОВ МЯГКОЙ ЯРОВОЙ ПШЕНИЦЫ В ЛЕСОСТЕПИ САМАРСКОЙ ОБЛАСТИ

The purpose of research is creation of conditions for the formation of self-regulating entomocomplexes in agrocenoses with a significant competitive relations in the cultivation of spring wheat in the non-use of insecticides against pests. Insects was collected with an entomological net for 25-50 flaps in triple repeated in period of vegetation of wheat. In the conditions of the non-use of insecticides of entomokomplexes included insects-phytophagous which are potential vectors of viruses, phytoplasmas; suctorial and gnawing phytofagous; insects are developing inwardly wheat stems; entomophagous. Entomophagous regulating the density of phytophagous were represented by predators and parasites. In 2013-2016 Phyllotreta vittula, Oscinella pusilla, O. frit had a high density in the stage of seedling growth, Haplothrips tritici – in the stage of stem elongation of spring wheat. Against pests of seedlings in terms of their high density recommended for pre-treatment of seeds of spring wheat before sowing by system insecticide Cruiser, KC, without a negative impact on useful entomofauna of the agro-ecosystems. To the head emergence stage of spring wheat and the beginning of oviposition of Haplothrips tritici, its population was effectively reduced by Aeolothrips pascidutus. Development of cereal aphids was annualy kept Hippodamia variegata (Coccinellidae).

МОНИТОРИНГ ЭНТОМОКОМПЛЕКСОВ МЯГКОЙ ОЗИМОЙ ПШЕНИЦЫ В ЛЕСОСТЕПИ САМАРСКОЙ ОБЛАСТИ

The purpose of researches is to study the effect of non-pesticidal pest against the background of soft winter wheat cultivation for seasonal dynamics of composition and abundance of pests and their entomophages in the conditions of Samara Region forest-steppe. Insects was collected with an entomological net for 10-50 flaps in triple repeated in autumn and spring-summer periods of wheat vegetation. In the conditions of the non-use of insecticides of entomocomplexes included insects-phytophagous which are potential vectors of viruses, phytoplasmas; suctorial and gnawing phytofagous; insects are developing inwardly wheat stems; entomophagous. Entomophagous regulating the density of phytophagous were represented by predators and parasites. In 2012-2013 main vector of phytoplasmas (Psammotettix striatus) and insects are developing inwardly wheat stems (Oscinella pusilla, O. frit, Delia platura) had a high density in the autumn period in the stage of wheat seedling growth and in spring in the stage of stem elongation. In 2013-2014 the density of any pests were not reached economic threshold values.

Thrips Species (Thysanoptera: Thripidae) in Brazilian Papaya (Brassicales: Caricaceae) Orchards as Potential Virus Vectors

Thrips (Thysanoptera: Thripidae) are pests of many fruit crops because they cause feeding damage or act as virus vectors. Seven thrips species were collected using Moericke yellow traps in papaya (Brassicales: Caricaceae) orchards, and Selenothrips rubrocinctus (Giard), the most frequent one (76.6%), occurred during all months evaluated. This is the first record of Frankliniella schultzei (Trybom) and F. australis Morgan in papaya orchards. Some of these species are minor pests of papaya, but some of them, such as F. schultzei, were reported as virus vectors to other commercial crops. The importance of these findings and needs for future research are discussed.

Molecular and immunological characterization of a DNA-launched yellow fever virus 17D infectious clone.

Yellow fever virus (YFV)-17D is an empirically developed, highly effective live-attenuated vaccine that has been administered to human beings for almost a century. YFV-17D has stood as a paradigm for a successful viral vaccine, and has been exploited as a potential virus vector for the development of recombinant vaccines against other diseases. In this study, a DNA-launched YFV-17D construct (pBeloBAC-FLYF) was explored as a new modality to the standard vaccine to combine the commendable features of both DNA vaccine and live-attenuated viral vaccine. The DNA-launched YFV-17D construct was characterized extensively both in cell culture and in mice. High titres of YFV-17D were generated upon transfection of the DNA into cells, whereas a mutant with deletion in the capsid-coding region (pBeloBAC-YF/ΔC) was restricted to a single round of infection, with no release of progeny virus. Homologous prime-boost immunization of AAD mice with both pBeloBAC-FLYF and pBeloBAC-YF/ΔC elicited specific dose-dependent cellular immune response against YFV-17D. Vaccination of A129 mice with pBeloBAC-FLYF resulted in the induction of YFV-specific neutralizing antibodies in all vaccinated subjects. These promising results underlined the potential of the DNA-launched YFV both as an alternative to standard YFV-17D vaccination and as a vaccine platform for the development of DNA-based recombinant YFV vaccines.

Integrative diagnosis of the needle nematodeLongidorus jonesiaffecting forest in southernJapan

SummaryThe occurrence of a parthenogenetic population ofLongidorus jonesiin the rhizosphere of aPrunussp. tree in a mixed evergreen forest is reported for the first time inMiyazaki (Miyazaki prefecture), southernJapan, and constitutes the first report of this species inJapan. Nematode diagnosis matched well with the original description in India and a subsequent report inChina. Morphometric traits of theJapanese population were characterized by a longer odontostyle length (123–142.5vs. 107–120 μm) and some differences in c ratio (95.9–131.5vs. 140–185) with respect to the original description, but closer to theChinese population. This difference could be considered as geographical intraspecific variability. Molecular characterization from nuclear ribosomalRNAgenes [D2‐D3 expansion segments of large ribosomal subunit (28S) and internal transcribed spacer 1 (ITS1)] was provided for the first time. Molecular analysis ofD2‐D3 andITS1 showed a close relationship withL. diadecturus, a virus‐vector nematode, by 94 and 79% similarity, respectively. The similarities in morphology, molecular and ecology (L. jonesiandL. diadecturusare feeding mainly onPrunusspecies) suggest that this species could be a potential virus vector, as it is the case withL. diadecturusandpeach rosette mosaic virus.

Abundance and Species Richness of Leafhoppers and Planthoppers (Hemiptera: Cicadellidae and Delphacidae) in Brazilian Maize Crops

Insects in the Cicadellidae and Delphacidae families, common in grasses, are an important group of vectors of viruses and mollicutes, which cause diseases in several plant species. The goal of this study was to evaluate the abundance and species richness of Cicadellidae and Delphacidae and the presence of potential vectors of viruses and mollicutes in maize crops in Brazil. Insects were collected using sweep nets in maize crops in 48 counties of 8 states, distributed in 4 regions of Brazil in the yr 2005, 2006 and 2007, with a total of 198 samples. The collected material was screened, and the leafhoppers and planthoppers were identified at the species level. A total of 4233 Cicadellidae specimens, including 30 species, and 205 Delphacidae specimens, including 9 species, were collected. The most abundant species was Dalbulus maidis (Delong & Wolcott) representing 90.1% of leafhoppers and planthoppers. Abundance and species richness differences were observed between the northeast and center-south regions of Brazil. Eight species of leafhoppers and planthoppers were identified as vectors or potential vectors of viruses and mollicutes in maize, although some of these viruses are not reported in Brazil. Among these species, we identified the planthoppers, Caenodelphax teapae (Fowler), Peregrinus maidis Ashmed, Pyrophagus tigrinus Remes Lenicov & Varela and Toya propinqua (Fieber) are experimental vectors of Mal de Río Cuarto virus, which is a quarantine virus in Brazil. Two Cicadellidae species and 3 Delphacidae species were reported for the first time in Brazil.

Measurement of the Infection and Dissemination of Bluetongue Virus in Culicoides Biting Midges Using a Semi-Quantitative RT-PCR Assay and Isolation of Infectious Virus

Background Culicoides biting midges (Diptera: Ceratopogonidae) are the biological vectors of globally significant arboviruses of livestock including bluetongue virus (BTV), African horse sickness virus (AHSV) and the recently emerging Schmallenberg virus (SBV). From 2006–2009 outbreaks of BTV in northern Europe inflicted major disruption and economic losses to farmers and several attempts were made to implicate Palaearctic Culicoides species as vectors. Results from these studies were difficult to interpret as they used semi-quantitative RT-PCR (sqPCR) assays as the major diagnostic tool, a technique that had not been validated for use in this role. In this study we validate the use of these assays by carrying out time-series detection of BTV RNA in two colony species of Culicoides and compare the results with the more traditional isolation of infectious BTV on cell culture.Methodology/Principal FindingsA BTV serotype 1 strain mixed with horse blood was fed to several hundred individuals of Culicoides sonorensis (Wirth & Jones) and C. nubeculosus (Mg.) using a membrane-based assay and replete individuals were then incubated at 25°C. At daily intervals 25 Culicoides of each species were removed from incubation, homogenised and BTV quantified in each individual using sqPCR (Cq values) and virus isolation on a KC-C. sonorensis embryonic cell line, followed by antigen enzyme-linked immunosorbent assay (ELISA). In addition, comparisons were also drawn between the results obtained with whole C. sonorensis and with individually dissected individuals to determine the level of BTV dissemination.Conclusions/SignificanceCq values generated from time-series infection experiments in both C. sonorensis and C. nubeculosus confirmed previous studies that relied upon the isolation and detection of infectious BTV. Implications on the testing of field-collected Culicoides as potential virus vectors by PCR assays and the use of such assays as front-line tools for use in diagnostic laboratories in this role are discussed.

VIRUS DISEASES OF POTATOES - INTENSITY OF SPREADING, VECTORS AND PESTICIDE CONTROL

Potatoes are one of the most important food crops in Albania. Virus diseases on this crop are the major threat to the production. According to the EPPO list the most spread and important viruses in Albania are Potato virus X (PVX), Potato virus Y (PVY), Potato leafroll virus (PLRV). The identification of the viruses is done using ELISA test. Monitoring of the potential virus vectors is performed. Samples have been collected in spring and autumn during the plant vegetation. Some species of aphids vectors like Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Aulacorthum solani (Kaltenbach) were observed. Data was collected for vector control, and the number of insecticide treatments together with the area of the treated surface was taken into account.

Resistance of squash cultivars to Aphis gossypii

The Cucurbitaceae plants are damaged by attack of a wide spectrum of insects and microorganisms. Among the sucker insects causing damages on squash Cucurbita pepo (L.), the aphid Aphis gossypii (Glover) (Hemiptera: Aphididae) is pointed as one of the most important, once their nymphs and adults suck the sap of the leaves continuously, besides being potential vector of virus. The present research evaluated different cultivars, aiming to identify the resistance against this aphid. The cultivars Novita, Sandy, Caserta Cac Melhorada, Novita Plus, Samira, AF-2858 and Caserta TS were used in laboratory assays (T= 25±2ºC; RH= 70±10% and fotophase= 12 h). In the immature phase the duration of nymphal instars was evaluated, the total duration and their viability, confining individuals on leaf disks from cultivars. In the adult phase the duration of reproductive period, the fecundity and the biological cycle were observed. The cultivar 'Sandy' expressed high level of antibiosis and feeding non-preference against A. gossypii, increasing the nymphal stage and causing mortality near to 70%. Besides, this cultivar reduced the production of nymphs and the longevity of the insects. The 'Novita Plus' cultivar also induced significant nymphal mortality, however in lower levels than those verified in 'Sandy', indicating a moderate resistance.

Light trapping of biting midges Culicoides spp. (Diptera: Ceratopogonidae) with green light‐emitting diodes

Abstract A study of responses by Culicoides spp. to light traps with light‐emitting diodes (LEDs) confirmed that the livestock virus vector, Culicoides brevitarsis Kieffer, was preferentially attracted to green light. Four species shown previously to respond to blue light exhibited significantly higher responses to ultraviolet (UV) light. Field trials comparing green LEDs with incandescent lights in New South Wales, Northern Territory and East Timor confirmed the superiority of green LEDs for catching C. brevitarsis. The green LED traps also had a significant advantage over incandescent traps for a wide range of Culicoides species. These included: species whose ultimate preference was for UV, most species that are proven or potential vectors of viruses affecting Australian livestock and native animals and the main species affecting humans in northern Australia. Use of green LEDs has been adopted for trapping C. brevitarsis, especially in its marginal and low‐density areas, and for detecting incursions of new Culicoides spp. into Australia. Use could be possible for species in other insect Orders.

Paratrichodorus divergens sp. n., a new potential virus vector of tobacco rattle virus and additional observations on P. hispanus Roca & Arias, 1986 from Portugal (Nematoda: Trichodoridae)

AbstractDuring a survey of trichodorids in continental Portugal, a new trichodorid species, Paratrichodorus divergens sp. n., was found. It is described and illustrated with specimens from the type locality together with additional morphometric data and photographs of specimens obtained from soil samples collected in seven other localities. The species is characterised in the female by distinct drop-like to triangular oblique vaginal sclerotisations diverging outwards and sperm cells usually distributed all through the uteri, and in the male by thin, almost straight, striated spicules, the two posteriormost precloacal supplements being located relatively close to one another and usually opposite the distal third of the retracted spicules, presence of a slightly bilobed cloacal lip and sperm cells with a sausage-shaped nucleus. Paratrichodorus divergens sp. n. most closely resembles P. hispanus Roca & Arias, 1986 with which it often occurs in mixed populations. Additional information is also provided for P. hispanus. Coding of the features of the new species is given following the identification key of Decraemer and Baujard.

Emerging viral diseases.

We live in an era of rapidly changing global landscapes and local environments. Viruses with RNA as their genetic material can quickly adapt to and exploit these varying conditions because of the high error rates of the virus enzymes (polymerases) that replicate their genomes. It comes as no surprise, then, that several prominent recent examples of emerging or re-emerging diseases are caused by RNA viruses. However, a complex interplay of factors can influence disease emergence. In addition to virus genetic variation (mutation, recombination, and reassortment), environmental factors (including ecological, social, health care, and behavioral influences) can play important roles. These can include (i) changing weather patterns (e.g., El Nino effects) and damming of rivers, which alters potential virus vector or host abundance and distribution, and (ii) tropical deforestation, which brings humans in close contact with these species-rich (hosts and their parasites) environments. Such factors, coupled with enormous increases in the human population during the last 50 years and urbanization in many developing countries, have greatly expanded the number of sampling events testing the fitness of RNA virus variants in different human cell backgrounds and potential transmission modes. This change, together with the advances in the speed and volume of global transportation, combines to create increased opportunity for emergence and re-emergence of viral diseases. The purpose of this review is to present some prominent recent examples of emerging and re-emerging RNA virus diseases (influenza, hantaviruses, Ebola virus, and Nipah virus) to try to convey a sense of the excitement within this field and the important advances coming about as new technologies are being applied to research the basic question of how new disease outbreaks occur and whether we can gain predictive capability.

Incidence of thrips and aphids as potential virus vectors in field tomatoes

Incidence of thrips and aphids as potential virus vectors in field tomatoes

Seasonal Abundance of Aphid-borne Virus Vectors (Homoptera: Aphididae) in Flue-cured Tobacco as Determined by Alighting and Aerial Interception Traps

Seasonal phenology of alate aphids migrating into and through flue-cured tobacco fields and use of aphid trap data to identify important aphid species as potential virus vectors were investigated. Aerial interception traps and alighting traps were found to sample different aphid populations. Of the aphid taxa caught, only two, Myzus persicae (Sulzer) and Dactynotus sp., were recorded by both trap types. The first period of alate aphid activity was indicated by both trap types 12–16 days after transplanting of tobacco. A second period of alate activity was indicated by the alighting traps 30–40 days after transplanting. M. persicae , the only tobacco-colonizing aphid in North Carolina, accounted for ca. 90% of the aphids collected in the second period; >95% of the aphids collected during the first period were noncolonizing species. Aerial interception traps did not detect migration of M. persicae into tobacco. The utility of examining the number of aphids alighting per plant, rather than the number of aphids caught per trap, is discussed in relation to actual insect pressure and virus spread.

Sampling for aphids by traps and by crop inspection

SUMMARYThe catches of thirty aphid genera and species during 3 years in a suction trap at 40 ft and on a yellow cylindrical sticky trap at 5 ft at Rothamsted and Broom's Barn are tabulated. Suction‐trap catches were the more consistent but both were more effective at recording the first seasonal immigration of Myzuspersicae (Sulz.) and Aphis fabae Scop, than the British Sugar Corporation crop‐inspection scheme.The catches show the differential attraction to yellow by different species, the effects of local vegetation, and the seasonal distribution of aphids that are crop pests or potential vectors of viruses.