Uroleucon Sonchi Research Articles

First report of costus stripe mosaic virus infecting Tradescantia spathacea plants in Brazil.

Tradescantia spathacea (family Commelinaceae) is cultivated worldwide as an ornamental (Golczyk et al., 2013) and as medicinal plant (Tan et al., 2020). In 2019, 90 of ~180 plants of T. spathacea, grown in two beds of 4 m2 and exhibiting leaf mosaic were found in an experimental area at ESALQ/USP (Piracicaba municipality, São Paulo state, Brazil). Potyvirus-like flexuous filamentous particles were observed by transmission electron microscopy in foliar extracts of two symptomatic plants stained with 1% uranyl acetate. Total RNA was extracted using the Purelink viral RNA/DNA kit (Thermo Fisher Scientific) from leaves of two symptomatic plants and separately subjected to a reverse transcription polymerase chain reaction (RT-PCR). The potyviruses degenerate pairs of primers CIFor/CIRev (Ha et al. 2008), which amplifies a fragment corresponding to part of the cylindrical inclusion protein gene, and WCIEN/PV1 (Maciel et al. 2011), which amplifies a fragment containing part of the capsid protein gene and the 3' untranslated region, were used. The expected amplicons (~700bp) were obtained from both total RNA extracts. Two amplicons from one sample were purified using the Wizard SV Gel and PCR Clean-Up System kit (Promega) and directly sequenced in both directions at Macrogen Inc (Seoul, South Korea). The obtained nucleotide sequences (GenBank MW430005 and MW503934) shared 95.32% and 97.79% nucleotide identity, respectively, with the corresponding sequences of the Brazilian isolate of the potyvirus costus stripe mosaic virus (CoSMV, MK286375) (Alexandre et al. 2020). Extract from an infected plant of T. spathacea was mechanically inoculated in 10 healthy plants of T. spathacea and two plants each of the following species: Capsicum annuum, Chenopodium amaranticolor, Commelina benghalensis, Datura stramonium, Gomphrena globosa, Nicandra physaloides, Nicotiana tabacum cvs. Turkish and Samsun, Solanum lycopersicum, T. palida, and T. zebrina. All T. spathacea plants exhibited mosaic and severe leaf malformation. C. benghalensis plants developed mild mosaic, whereas infected T. zebrina plants were asymptomatic. The plants of other species were not infected. RT-PCR with specific CoSMV primers CoSMVHC-F and CoSMVHC-R (Alexandre et al. 2020) confirmed the infection. Nucleotide sequences of amplicons obtained from experimentally inoculated T. spathacea and T. zebrina (MW430007 and MW430008) shared 94.56% and 94.94% identity with the corresponding sequence of a Brazilian CoSMV isolate (MK286375). None of eight virus-free plants of T. spathacea inoculated with CoSMV using Aphis craccivora exhibited symptoms, nor was CoSMV detected by RT-PCR. Lack of CoSMV transmission by A. solanella, Myzus persicae, and Uroleucon sonchi was previously reported (Alexandre et al. 2020). T. spathacea plants are commonly propagated vegetatively, and by seeds. Virus-free seeds, if available, can provide an efficient and easy way to obtain healthy plants. Only three viruses were reported in plants of the genus Tradescantia: Commelina mosaic virus, tradescantia mild mosaic virus, and a not fully characterized potyvirus (Baker and Zettler, 1988; Ciuffo et al., 2006; Kitajima 2020). CoSMV was recently reported infecting Costus spiralis and C. comosus (Alexandre et al. 2020). As far as we know, this is the first report of CoSMV infecting T. spathacea plants.

Temporal and spatial progress of Cowpea aphid-borne mosaic virus (CABMV) in passion fruit (Passiflora edulis Sims)

Among the diseases that affect passion fruit, those causing fruit woodiness is considered the most important. Cowpea aphid-borne mosaic virus (CABMV) is an important vírus that is transmitted by several aphid species during the bite, making the use of insecticides infeasible to control these vectors. In order to understand the epidemiological behavior of the disease, this study aimed to study the temporal progress and spatial pattern of CABMV in the field. Healthy seedlings of passion fruit with 2.0 meters height were implanted in the field condition at the experimental station of the IDR-Paraná, Brazil. The evaluations were performed weekly observing the symptoms of blister, mosaic, chlorosis and crinkled leaves. For the analyses, the logistic, gompertz and monomolecular models were adjusted to CABMV incidence data in passion fruit. The spatial pattern of the disease was characterized by the dispersion index and Taylor's Power Law. The logistic model was the one that best described the progress in the incidence of the disease. The incidence progress rate of CABMV was 0.037, 0.077 and 0.060 % day-1. At the beginning of the epidemic, the pattern was random. The initial dispersion mechanism was occured through aphid vectors, como Aphis gossypii Glover, Aphis fabae Scopoli, Aphis solanella Theobald, Toxoptera citricida Kilkaldy, Uroleucon ambrosiae Thomas and Uroleucon sonchi L. infected with CABMV that starts its test bite randomly. The pattern of disease dispersion began to be added when the incidence of plants reached 10 and 7%, in the 2015/16 and 2017/18 harvests, respectively. The random spatial pattern suggested that infected aphids enter several points of the orchard and infected plants become a source for secondary infections, characterizing aggregate pattern. Thus, the eradication of alternative hosts abroad can be adopted as management strategies of CABMV

Costus stripe mosaic virus, a tentative new member of the genus Potyvirus.

Morphological, biological, serological, and molecular tests underpin the description of costus stripe mosaic virus (CoSMV) as a new member of the genus Potyvirus, family Potyviridae. Found affecting the native ornamental Costus spiralis in Brazil, the pathogen showed a severely restricted natural and experimental host range. Excluding the poly(A) tail, the CoSMV genome contains a large open reading frame (ORF) of 9,446 nucleotides that encodes a polyprotein with 3,046 amino acids, which is potentially cleaved into ten products, and a small ORF (77 amino acids) knows as PIPO. Genome analysis demonstrated the highest CoSMV nucleotide sequence identity to onion yellow dwarf virus (51.79%). No evidence of recombination was detected in the CoSMV genome, and phylogenetic analysis revealed its basal position in a group formed by members of the genus Potyvirus, along with Cyrtanthus elatus virus A (Vallota speciosa virus) and canna yellow streak virus. CoSMV was not transmitted by aphids of the species Aphis solanella, Myzus persicae or Uroleucon sonchi, which could be due to mutations in the HC-Pro motifs required for aphid transmission. A divergence in the P1 protein cleavage site was found when compared to other members of the family Potyviridae. Based on its unique biological and molecular characteristics and the current species demarcation criteria, we propose CoSMV to be a new tentative member of the genus Potyvirus.

The influence of aphid-produced honeydew on parasitoid fitness and nutritional state: A comparative study

Honeydew is a sugar-rich resource excreted by many hemipteran species and is a key food source for other insect species such as ants and parasitoid wasps. Here, we evaluated the nutritional value of 14 honeydews excreted by 13 aphid species for the generalist aphid parasitoid Lysiphlebus testaceipes to test a series of hypotheses concerning variation in the nutritional value of honeydew. There was a positive correlation between the body sugar content of honeydew-fed parasitoids and their longevity. This information is valuable for biological control researchers because it demonstrates that the nutritional state of honeydew-fed parasitoids in the wild can indicate their fitness, independently of the honeydew source they have fed on.Although the carbohydrate content and longevity of L. testaceipes differed greatly among the different honeydews, we did not find a significant effect of aphid or host plant phylogeny on these traits. This result suggests that honeydew is evolutionarily labile and may be particularly subject to ecological selection pressures. This becomes apparent when considering host aphid suitability: Schizaphis graminum, one of the most suitable and commonly used hosts of L. testaceipes, produced honeydew of the poorest quality for the parasitoid whereas Uroleucon sonchi, one of the few aphids tested that cannot be parasitized by L. testaceipes, excreted the honeydew with the highest nutritional value. These data are consistent with the hypothesis that hemipterans are subject to selection pressure to minimize honeydew quality for the parasitoids that attack them.

Transmission of Moroccan watermelon mosaic virus (MWMV) by Aphids in Greece.

The aphid-transmitted Moroccan watermelon mosaic virus (MWMV; Potyvirus, Potyviridae) is an emerging pathogen in cucurbit crops in the Mediterranean basin but information on its transmitting vector species is limited. This study aimed to record the competence of 22 species of the Greek aphid fauna to vector MWMV. Timed-probe transmission experiments and arena tests were performed using laboratory colonies of aphid species abundant in field surveys; less common species were tested as apterous individuals collected directly from field plants in mass-inoculation (nonpersistent) tests. Depending on the test, aphids were tested in cohorts of 10 or 20 individuals on zucchini (Cucurbita pepo L.) plants and the frequency of transmission was calculated for a single aphid. Among 12 species tested in timed-probe transmission tests, Myzus persicae nicotianae (74.0%) appeared to be the most efficient vector, followed by M. persicae (48.0%), Aphis gossypii (11.8%), an unidentified Aphis sp. (11.8%), and A. spiraecola (11.0%). Alatae of nine species tested in arena tests transmitted the virus in rates varying from 0.7 to 53.6%; M. persicae was the most efficient species in virus spread. In mass-inoculation tests, the probability that apterae of 12 aphid species collected from field plants transmitted MWMV fluctuated from 0.3 to 5.3%. No transmission was obtained by Brevicoryne brassicae. The following species are reported as new vectors of MWMV: A. fabae, A. nerii, A. spiraephaga, A. umbrella, Capitophorus eleaegni, Dysaphis (Pomaphis) pyri, Macrosiphoniella sanborni, Macrosiphum rosae, Myzocallis castanicola, Myzus persicae nicotianae, M. cerasi, M. varians, Phorodon humuli, Ovatus crataegarius, Takecallis arundicolens (first report in Greece), Uroleucon sonchi, and U. (Uromelan) aeneum. These results contribute to a better understanding of MWMV epidemiology.

Potential plant–aphid–fungal associations aiding conservation biological control of cereal aphids in Argentina

The overall aim of this study was to identify potential associations between aphids and plants as reservoirs of entomophthoralean fungi. A survey of weeds associated with wheat field borders in two different localities was performed over two years, from April 2010 to April 2012 in the Pampeana central region, Argentina. On each sampling date, five individuals of each plant species were randomly selected, and healthy and infected aphids were collected and quantified once a month. The taxonomic identities of both aphid hosts and entomophthoralean fungi were established. Aphid–fungus associations identified as favorable for inclusion in conservation biological control strategies in borders of wheat crops are the following: Sonchus oleraceus (L.)/Hyperomyzus carduellinus (Theobald), Uroleucon sonchi (L.)/Pandora neoaphidis (Remaudière & Hennebert) Humber; S. oleraceus (L.)/H. carduellinus (Theobald)/Zoophthora radicans (Brefeld) Batko; Lamium amplexicaule (L.)/Cryptomyzus korschelti Bôrner/P. neoaphidis, Z. radicans, Entomophthora planchoniana Cornu; Foeniculum vulgare (Miller)/Dysaphis apiifolia (Theobald)/Z. radicans; Morrenia brachystephana Griseb/Aphis nerii Boyer de Fonscolombe/P. neoaphidis and Brassica rapa L./Brevicoryne brassicae (L.)/P. neoaphidis.

Avoiding incidental predation by mammalian herbivores: accurate detection and efficient response in aphids

Mammalian herbivores eat plants that may also provide food and shelter for insects. The direct trophic effect of the browsing and grazing of mammalian herbivory on insects, which is probably prevalent in terrestrial ecosystems, has been mostly neglected by ecologists. We examined how the aphid Uroleucon sonchi L. deals with the danger of incidental predation by mammalian herbivores. We found that most (76%) of the aphids in a colony survive the ingestion of the plant by a feeding herbivore. They do so by sensing the combination of heat and humidity in the herbivore's breath and immediately dropping off the plant in large numbers. Their ability to sense the herbivore's breath or their tendency to drop off the plant weakens as ambient temperature rises. This could indicate a limitation of the aphids' sensory system or an adaptation that enables them to avoid the hostile conditions on a hot ground. Once on the ground, U. sonchi is highly mobile and capable of locating a new host plant by advancing in a pattern that differs significantly from random movement. The accurate and efficient defense mechanism of U. sonchi emphasizes the significance of incidental predation as a danger to plant-dwelling invertebrates.

Occurrence of Beet western yellows virus and its aphid vectors in over-summering broad-leafed weeds and volunteer crop plants in the grainbelt region of south-western Australia

During the summer periods of 2000, 2001, and 2002, presence of Beet western yellows virus (BWYV) was assessed in tests on samples from at least 12 broad-leafed weed species and 5 types of volunteer crop plants growing in the grainbelt region of south-western Australia. In 2000, BWYV was detected in 2 of 35 sites in 2% of 1437 samples, whereas in 2001 and 2002 the corresponding figures were 3 of 108 sites in 0.04% of 8782 samples, and 1 of 30 sites in 0.08% of 2524 samples, respectively. The sites with infection were in northern, central, and southern grainbelt districts, and in high and medium rainfall zones. The hosts in which BWYV was detected were the weeds Citrullus lanatus (Afghan or wild melon), Conzya spp. (fleabane), Navarretia squarrosa (stinkweed), and Solanum nigrum (blackberry nightshade), and the volunteer crop plant Brassica napus (canola). Small populations of aphids were found over-summering at 28% (2000), 4% (2001), and 17% (2002) of sites, mostly infesting volunteer canola and Raphanus raphanistrum (wild radish). They occurred in high, medium, and low rainfall zones, but were only found in central and southern grainbelt districts. The predominant aphid species found was Brevicoryne brassicae, with Acyrthosiphon pisum, Brachycaudus helichrysi, Hyperomyzus lactucae, Lipaphis erysimi, Myzus persicae, and Uroleucon sonchi present occasionally. The importance of these findings in relation to the epidemiology and control of BWYV in the grainbelt is discussed.

AN ARGENTINEAN ISOLATE OF LEEK YELLOW STRIPE VIRUS FROM LEEK CAN BE TRANSMITTED TO GARLIC

Leek yellow stripe virus (LYSV) causes mosaic in garlic and leek, together with other potyviruses, carlaviruses and allexiviruses. An isolate of LYSV from leek plants presenting typical yellow stripes, near Cordoba, Argentina, was mechanically transmitted and caused chlorotic local lesions in Chenopodium amaranticolor and C. quinoa. Only two out of 40 onion plants mechanically inoculated were infected. The isolate was easily transmitted to garlic mechanically (14 out of 20 plants) and by aphids (2 out of 10 plants), especially to young plants. Myzus persicae, Rhopalosiphum maidis, R. padi, Schizaphis graminum, Aphis gossypii, A. nerii, Uroleucon sonchi and Hyperomyzus carduellinus were able to transmit the virus. Abundant inclusion bodies were observed in thin sections. The modal length of the virion was 825 nm, and the capsid protein was 34 kDa in size, as determined by SDS-PAGE. LYSV from leek and Onion yellow dwarf virus were compared using several antisera, including one prepared against our isolate and their serological relatedness confirmed. The 3´-nontranslated region (3´-NTR) of our isolate (accession no. AY007693) showed 94% identity with that of LYSV (accession no. X89711) and the deduced amino acid sequence for the coat protein had 97% homology.

Uroleucon sonchi (Linnaeus) (Hemiptera: Aphididae) in Australia

Uroleucon sonchi, an aphid species of Palaearctic origin, is a recent adventive to Australia. It is now widespread in anthropic areas of all states and the Australian Capital Territory, principally on sowthistles (Sonchus spp.) but also on lettuce. It is occasionally parasitised by Aphidius sonchi Marshall (Hymenoptera: Braconidae). Its possible economic importance in Australia is discussed. The species is also recorded for the first time from Norfolk and Philip Islands.

How nutritionally imbalanced is phloem sap for aphids?

AbstractAphids harbour intracellular symbionts (Buchnera) that provide their host with amino acids present in low amounts in their diet, phloem sap. To find out the extent to which aphids depend on their symbionts for synthesis of individual essential amino acids, we have evaluated how well phloem sap amino acid composition matches the aphids' needs. Amino acid compositions of the ingested phloem sap were compared to amino acids in aphid body proteins and also to available information about optimal diet composition for other plant feeding insects. Phloem sap data from severed stylets of two aphid species, Rhopalosiphum padi (L.) (Homoptera: Aphididae) feeding on wheat, and Uroleucon sonchi (L.) (Homoptera: Aphididae) feeding on Sonchus oleraceus (L.), together with published information on phloem sap compositions from other plant species were used.Phloem sap has in general only around 20% essential amino acids, with a range from 15–48%. Aphid body proteins and optimal diets for two other plant feeding insects have around 50%. The phloem sap of early flowering S. oleraceus ingested by U. sonchi contained 48%, which seems to be exceptional. Aphids feeding on different plants appear to be very differently dependent on their symbionts for their overall essential amino acid synthesis, due to the large variation in proportion of essential amino acids in phloem sap from different plants.The profile of the essential amino acids in phloem sap from different plant species corresponds rather well to profiles of both aphid body proteins and optimal diets determined for plant feeding insects. However, methionine and leucine in phloem sap are in general low in these comparisons, suggesting a higher dependence on the symbiont for synthesis of these amino acids. Concentrations of several essential amino acids in phloem from different plant species seem to vary together, suggesting that levels of symbiont provisioning of different amino acids are adjusted in parallel.

Endosymbionts ( Buchnera ) of the Aphid Uroleucon sonchi Contain Plasmids with trpEG and Remnants of trpE Pseudogenes

The aphid Uroleucon sonchi contains a prokaryotic endosymbiont (Buchnera) with plasmids having trpEG as well as remnants of trpE pseudogenes. In this respect it resembles Buchnera from the aphid Diuraphis noxia. Phylogenetic trees based on trpE (plasmid gene) and trpB (chromosomal genes) from eight species of aphids are congruent, indicating a lack of exchange of plasmids among endosymbionts from different aphid species.

Inheritance of partial resistance to the leaf aphids Macrosiphum euphorbiae and Uroleucon sonchi in lettuce

SummaryThe genetics of partial resistance (PR) of lettuce to the leaf aphid species Macrosiphum euphorbiae and Uroleucon sonchi was studied in F1 and F2 generations of six crosses between four cultivars. Partial resistance inherited mainly additively. With M. euphorbiae the estimates of broad‐sense F2 heritability were low and non‐significant in crosses between parents of the same resistance level (S x S and PR x PR), and high (0.69‐0.76) in crosses between parents of different resistance level (PR x S). The level of resistance in lettuce cultivars ‘Charan’ and ‘Marbello’ led to a marked reduction in percentage of plants with colonies of M. euphorbiae in a field experiment. With U. sonchi the highest estimates of F2 heritability were found in ‘Charan x ‘Avoncrisp’ (0.51) and ‘Charan’ x ‘Chou de Naples' (0.48). In the cross ‘Charan’ x ‘Marbello’ (PR x PR) no significant segregation for resistance to M. euphorbiae was found, indicating that these cultivars may have the same genetic constitution for resistance to M. euphorbiae.‘Charan’ has additional genes for resistance to U. sonchi, that are not, or only weakly linked to the gene(s) for resistance to M. euphorbiae. The heritability estimates for the partial resistance to M. euphorbiae and U. sonchi indicate that it is possible to effectively select for these traits in plant breeding programmes.

Resistance in lettuce to the leaf aphids Macrosiphum euphorbiae and Uroleucon sonchi

SummaryScreening of 90 lettuce genotypes revealed great variation in resistance to the leaf aphids Macrosiphum euphorbiae and Uroleucon sonchi. Butterhead genotypes were usually, but not always, moderately to highly resistant to both aphid species. On the other hand mcjst crisphead genotypes had little or no resistance to both species. The results for the modern crisphead cultivar Marbello showed that it is possible to transfer resistance to M. euphorbiae from the butterhead to the crisphead type. Breeding programmes should benefit from the fact that in many cases resistance to M. euphorbiae and to U. sonchi, and in some cases also to other aphid species, was found in the same genotype. However, correlations between resistance scores for M. euphorbiae and U. sonchi were rather low, indicating that some components of resistance are specific to only one of the aphid species. Also within three groups of genotypes with resistance to Nasonovia ribisnigri, Myzus persicae and Pemphigus bursarius, respectively, large differences in resistance to M, euphorbiae and U. sonchi were found. The accumulation in one genotype of various resistance components to create cultivars with broad aphid resistance is a challenging and difficult task for practical plant breeding.