| properties of a virus causing mosaic and leaf curl disease of celosia argentea l. in nigeria. | a sap transmissible virus, causing mosaic and leaf curl disease of celosia argentea, was isolated at vegetable farms in amuwo odofin, tejuoso, and abule ado, lagos, nigeria. the virus had a restricted host range confined to a few species of the amaranthaceae, chenopodiaceae and solanaceae families. it failed to infect several other species of the aizoaceae, brassicaceae, cucurbitaceae, fabaceae, lamiaceae, malvaceae, poaceae and tiliaceae families. the virus was transmitted in a non-persistent m ... | 1998 | 9842442 |
| progress on strain differentiation of citrus tristeza virus and its application to the epidemiology of citrus tristeza disease. | citrus tristeza virus (ctv) occurs in most citrus producing regions of the world, and it is the most serious viral pathogen of citrus. with the recent establishment of the brown citrus aphid, toxoptera citricida, its most efficient vector, on madeira island (portugal) and in florida (usa) and the countries of the caribbean basin, the impact of ctv is likely to increase in these regions. since there are many strains of ctv and ctv infections frequently occur as mixtures of several strains, it is ... | 2000 | 11137165 |
| intra- and interspecific interactions between lysiphlebus testaceipes and lipolexis scutellaris (hymenoptera: aphidiidae) reared on toxoptera citricida (homoptera: aphididae). | classical biological control of the brown citrus aphid toxoptera citricida kirkaldy in florida has involved the release of lipolexis scutellaris mackauer. lysiphlebus testaceipes cresson is already present in florida and also parasitizes t. citricida. because parasitoid-parasitoid interactions may affect the establishment of a newly introduced parasitoid species, intra- and interspecific larval interactions of both parasitoids were studied in the laboratory using t. citricida reared on citrus. f ... | 2003 | 12852589 |
| responses of lipolexis oregmae (hymenoptera: aphidiidae) to different instars of toxoptera citricida (homoptera: aphididae). | the effects of host instar of toxoptera citricida kirkaldy (homoptera: aphididae) on the performance of the parasitoid lipolexis oregmae (gahan) (hymenoptera: aphidiidae), originally lipolexis scutellaris mackauer, were evaluated in an effort to increase basic knowledge of this host-parasitoid association, improve field sampling methods, and potentially predict the success of parasitism in the field. l. oregmae was able to oviposit and develop in all four instars of t. citricida; however, there ... | 2003 | 14977104 |
| sucrose octanoate toxicity to brown citrus aphid (homoptera: aphididae) and the parasitoid lysiphlebus testaceipes (hymenoptera: aphidiidae). | we report the toxicological effects of a new biorational, synthetic sucrose octanoate (ava chemical ventures l.l.c., portsmouth, nh), on brown citrus aphid, toxoptera citricida (kirkaldy), nymphs and adults and to its native parasitoid lysiphlebus testaceipes (cresson). sucrose octanoate topically applied was equally toxic to brown citrus aphid adults and nymphs with lc50 and lc90 values ranging from 356 to 514 and 1029 to 1420 ppm, respectively. mortalities of both stages did not differ signifi ... | 2004 | 15384331 |
| aphid biology: expressed genes from alate toxoptera citricida, the brown citrus aphid. | the brown citrus aphid, toxoptera citricida (kirkaldy), is considered the primary vector of citrus tristeza virus, a severe pathogen which causes losses to citrus industries worldwide. the alate (winged) form of this aphid can readily fly long distances with the wind, thus spreading citrus tristeza virus in citrus growing regions. to better understand the biology of the brown citrus aphid and the emergence of genes expressed during wing development, we undertook a large-scale 5' end sequencing p ... | 2003 | 15841239 |
| citrus tristeza virus transmission by the toxoptera citricida vector: in vitro acquisition and transmission and infectivity immunoneutralization experiments. | citrus tristeza virus (ctv) is transmitted by several aphid species in a semi-persistent manner with toxoptera citricida, the brown citrus aphid (brca), being the most efficient. as yet, the molecular interactions between the virus and its aphid vectors have not been determined. this is the first report of aphids acquiring ctv from preparations through an artificial membrane and then transmitting it to receptor plants. the brca fed across artificial membranes on crude tissue preparations made fr ... | 2006 | 16490262 |
| phylogenetic and structural relationships of the pr5 gene family reveal an ancient multigene family conserved in plants and select animal taxa. | pathogenesis-related group 5 (pr5) plant proteins include thaumatin, osmotin, and related proteins, many of which have antimicrobial activity. the recent discovery of pr5-like (pr5-l) sequences in nematodes and insects raises questions about their evolutionary relationships. using complete plant genome data and discovery of multiple insect pr5-l sequences, phylogenetic comparisons among plants and animals were performed. all pr5/pr5-l protein sequences were mined from genome data of a member of ... | 2006 | 16736102 |
| population structure of citrus tristeza virus from field argentinean isolates. | we studied the genetic variability of three genomic regions (p23, p25 and p27 genes) from 11 field citrus tristeza virus isolates from the two main citrus growing areas of argentina, a country where the most efficient vector of the virus, toxoptera citricida, is present for decades. the pathogenicity of the isolates was determinated by biological indexing, single-strand conformation polymorphism analysis showed that most isolates contained high intra-isolate variability. divergent sequence varia ... | 2008 | 17999168 |
| occurrence of genetic bottlenecks during citrus tristeza virus acquisition by toxoptera citricida under field conditions. | in this study, we address the involvement of t. citricida in strain segregation and genetic bottleneck events by comparing the nucleotide diversity of ctv coat protein (cp) gene variants present in field-grown trees with that of variants retrieved from single apterous aphids. plant material and aphids were collected in orange orchards in the northern part of portugal. shoots from two trees that were found to be positive using elisa and twenty-four apterous aphids from these same trees were selec ... | 2008 | 18049792 |
| in silico analyses of peptide paracrines/hormones in aphidoidea. | the aphidoidea is an insect superfamily comprising most of the known aphid species. while small in size, these animals are of considerable economic importance as many members of this taxon are serious agricultural pests, inflicting physical damage upon crop plants and serving as vectors in the transmission of viral plant diseases. in terms of identifying the paracrines/hormones used to modulate behavior, particularly peptides, members of the aphidoidea have largely been ignored, as it is not tra ... | 2008 | 18725225 |
| plum pox in north america: identification of aphid vectors and a potential role for fruit in virus spread. | abstract thirteen aphid species were tested for their ability to transmit pennsylvania isolates of plum pox virus (ppv) collected in columbia (penn-3), franklin (penn-4), and york (penn-7) counties, pa. four species, aphis fabae, a. spiraecola, brachycaudus persicae, and myzus persicae, consistently transmitted ppv in preliminary transmission tests. two species, metopolophium dirhodum and rhopalosiphum padi, were occasional inefficient vectors. toxoptera citricida, from florida, also was an effe ... | 2004 | 18943108 |
| spatial and temporal analyses of citrus sudden death as a tool to generate hypotheses concerning its etiology. | abstract citrus sudden death (csd), a new disease of unknown etiology that affects sweet orange grafted on rangpur lime, was visually monitored for 14 months in 41 groves in brazil. ordinary runs analysis of csd-symptomatic trees indicated a departure from randomness of symptomatic trees status among immediately adjacent trees mainly within rows. the binomial index of dispersion (d) and the intraclass correlation (k) for various quadrat sizes suggested aggregation of csd-symptomatic trees for al ... | 2003 | 18944366 |
| examination of the effect of aphid vector population composition on the spatial dynamics of citrus tristeza virus spread by stochastic modeling. | abstract aphid vector species population composition is known to affect the spatial patterns of citrus tristeza virus (ctv) and the changes in these patterns over time. however, the biological processes that are associated with virus spread have not been well defined. the spatiotemporal dynamics of ctv were examined using data collected from research plots in the dominican republic and costa rica, where the brown citrus aphid (bca), toxoptera citricida, was the predominant species, and in florid ... | 1999 | 18944697 |
| survey methods for assessment of citrus tristeza virus incidence when toxoptera citricida is the predominant vector. | abstract citrus tristeza virus (ctv) incidence may be assessed by sampling groups of citrus trees, recording the groups as ctv positive (one or more infected trees) or ctv negative (no infected trees), and then calculating disease incidence at the scale of the individual tree by means of a formula involving incidence at the group scale and the number of trees per group. this procedure works well when the ctv status of a tree can be regarded as independent of the ctv status of other trees in the ... | 1999 | 18944721 |
| increase and patterns of spread of citrus tristeza virus infections in costa rica and the dominican republic in the presence of the brown citrus aphid, toxoptera citricida. | abstract citrus tristeza virus (ctv) was monitored for 4 years by monoclonal antibody probes via enzyme-linked immunosorbent assay in four citrus orchards in northern costa rica and four orchards in the dominican republic following the introduction of the brown citrus aphid, toxoptera citricida. the gompertz nonlinear model was selected as the most appropriate in most cases to describe temporal increase of ctv. ordinary runs analysis for association of ctv-positive trees failed to show a spatial ... | 1998 | 18944934 |
| complete genome sequences of two distinct and diverse citrus tristeza virus isolates from new zealand. | two citrus tristeza virus (ctv) isolates from new zealand that display distinct phenotypes were isolated, examined and sequenced in full. the first isolate, nz-m16, is largely asymptomatic and non-transmissible by the aphid vector toxoptera citricida, while the second, nz-b18, is highly transmissible and induces very severe symptoms on c. sinensis and c. aurantii. phylogenetic analysis of the genome sequences showed that both isolates were approximately 90-93% similar to the vt and t318 isolates ... | 2009 | 19629636 |
| sequence diversity on four orfs of citrus tristeza virus correlates with pathogenicity. | the molecular characterization of isolates of citrus tristeza virus (ctv) from eight locations in mexico was undertaken by analyzing five regions located at the opposite ends of the virus genome. two regions have been previously used to study ctv variability (coat protein and p23), while the other three correspond to other genomic segments (p349-b, p349-c and p13). our comparative nucleotide analyses included ctv sequences from different geographical origins already deposited in the genbank data ... | 2009 | 19642988 |
| comparative analysis of the acyrthosiphon pisum genome and expressed sequence tag-based gene sets from other aphid species. | to study gene repertoires and their evolution within aphids, we compared the complete genome sequence of acyrthosiphon pisum (reference gene set) and expressed sequence tag (est) data from three other species: myzus persicae, aphis gossypii and toxoptera citricida. we assembled ests, predicted coding sequences, and identified potential pairs of orthologues (reciprocical best hits) with a. pisum. pairwise comparisons show that a fraction of the genes evolve fast (high ratio of non-synonymous to s ... | 2010 | 20482638 |
| somatic hybridization for citrus rootstock breeding: an effective tool to solve some important issues of the mediterranean citrus industry. | the prevalence of sour orange rootstock in the southern and eastern part of the mediterranean basin is presently threatened by the spread of citrus tristeza virus (ctv) and its main vector toxoptera citricida, combined with abiotic constraints such as drought, salinity and alkalinity. the search for alternative ctv-resistant rootstocks that also withstand the other constraints is now considered an urgent priority for a sustainable citrus industry in the area. complementary progenitors can be fou ... | 2011 | 21225429 |
| three homopteran pests of citrus as prey for the convergent lady beetle: suitability and preference. | the convergent lady beetle, hippodamia convergens guérin-méneville (coleoptera: coccinellidae), is an important predator of soft-bodied insect pests in many regions of the united states, but generally uncommon in florida citrus. certain citrus producers in florida recently initiated releases of commercially available h. convergens from california against the asian citrus psyllid diaphorina citri kuwayama, vector of huanglongbing or citrus greening disease. however, there is little information o ... | 2011 | 22217767 |
| comparative profiling of micrornas in the winged and wingless english grain aphid, sitobion avenae (f.) (homoptera: aphididae). | micrornas (mirnas) are short single-stranded non-coding rnas that regulate gene expression, particularly during development. in this study, 345 mirnas were identified from the english green aphid, sitobion avenae (f.), of which 168 were conserved and 177 were s. avenae-specific. quantitative comparison of mirna expression levels indicated that 16 and 12 mirnas were significantly up-regulated in winged and wingless s. avenae small rna libraries, respectively. differential expression of these mirn ... | 2016 | 27762301 |
| symbiont diversity of aphis (toxoptera) citricidus (hemiptera: aphididae) as influenced by host plants. | aphids are well known for their association with endosymbiont bacteria. almost all aphids harbor buchnera aphidicola as an obligate symbiont and several other bacteria as facultative symbionts. associations of facultative symbionts and aphids are quite variable in terms of diversity and prevalence across aphid species. facultative symbionts can have a major impact on aphid bioecological traits. a number of factors shape the outcome of the facultative symbiont-aphid association, including aphid c ... | 2017 | 27872949 |
| sequence variation in two genes determines the efficacy of transmission of citrus tristeza virus by the brown citrus aphid. | vector transmission is an important part of the viral infection cycle, yet for many viruses little is known about this process, or how viral sequence variation affects transmission efficacy. here we examined the effect of substituting genes from the highly transmissible fs577 isolate of citrus tristeza virus (ctv) in to the poorly transmissible t36-based infectious clone. we found that introducing p65 or p61 sequences from fs577 significantly increased transmission efficacy. interestingly, repla ... | 2016 | 27644950 |
| minor coat and heat shock proteins are involved in the binding of citrus tristeza virus to the foregut of its aphid vector, toxoptera citricida. | vector transmission is a critical stage in the viral life cycle, yet for most plant viruses how they interact with their vector is unknown or is explained by analogy with previously described relatives. here we examined the mechanism underlying the transmission of citrus tristeza virus (ctv) by its aphid vector, toxoptera citricida, with the objective of identifying what virus-encoded proteins it uses to interact with the vector. using fluorescently labeled virions, we demonstrated that ctv bind ... | 2016 | 27520823 |
| identification, characterization and functional analysis of a chitin synthase gene in the brown citrus aphid, toxoptera citricida (hemiptera, aphididae). | chitin synthase (chs) is a crucial enzyme involved in the final step of the insect chitin biosynthetic pathway. in this study, we cloned the full-length cdna sequence of a chitin synthase gene (tcichs) from the brown citrus aphid, toxoptera citricida, an important citrus pest and the main vector of citrus tristeza virus worldwide. tcichs was expressed during the entire lifecycle and in all insect tissues examined. expression was highest in first-second-instar nymphs, nymph-adult transitions and ... | 2016 | 26991909 |
| reference gene validation for quantitative pcr under various biotic and abiotic stress conditions in toxoptera citricida (hemiptera, aphidiae). | the regulation of mrna expression level is critical for gene expression studies. currently, quantitative reverse transcription polymerase chain reaction (qrt-pcr) is commonly used to investigate mrna expression level of genes under various experimental conditions. an important factor that determines the optimal quantification of qrt-pcr data is the choice of the reference gene for normalization. to advance gene expression studies in toxoptera citricida (kirkaldy), an important citrus pest and a ... | 2015 | 26470351 |
| spatial and temporal spread of citrus tristeza virus and its aphid vectors in the north western area of morocco. | first report of citrus tristeza virus (ctv,closterovirus) in morocco datesback to 1961 in collections of citrus varieties. an exhaustive survey of citrus in the north of the country in 2009 revealed that ctv was spread all over the citrus production area. we attempted to evaluate the relative contribution of different aphid species in the spread of ctv disease in a citrus reticulata orchard at the loukkous region during 2 years (2012 and 2013). the overall ctv incidence estimated in the experime ... | 2016 | 25884375 |
| mild strain cross protection of tristeza: a review of research to protect against decline on sour orange in florida. | tristeza, caused by citrus tristeza virus (ctv), has long been present in florida but outbreaks of decline on sour orange rootstock were occasional events until the late 1970s. sour orange rootstock was valued for the high quality of fruit produced and was widely used because of its tolerance of citrus blight, a disease of unknown etiology. research was directed towards the selection and screening of mild strains of ctv which could protect against sour orange decline strains. following the intro ... | 2013 | 24046764 |
| characterization of an insect heterodimeric voltage-gated sodium channel with unique alternative splicing mode. | recent discovery of the heterodimeric voltage-gated sodium channels (nav) in two aphid species, acyrthosiphon pisum and myzus persicae, aroused interest in exploring whether this kind of channel is conserved for aphids. herewith, we aim to provide evidence for the conservation of heterodimeric navs in aphids and investigate whether they have unique splicing patterns. we found that the only identifiable nav from toxoptera citricida consisted of two subunits, forming a heterodimeric nav, which car ... | 2017 | 27816572 |
| formation of stylet sheaths in āere (in air) from eight species of phytophagous hemipterans from six families (suborders: auchenorrhyncha and sternorrhyncha). | stylet sheath formation is a common feature among phytophagous hemipterans. these sheaths are considered essential to promote a successful feeding event. stylet sheath compositions are largely unknown and their mode of solidification remains to be elucidated. this report demonstrates the formation and solidification of in āere (in air) produced stylet sheaths by six hemipteran families: diaphorina citri (psyllidae, asian citrus psyllid), aphis nerii (aphididae, oleander/milkweed aphid), toxopter ... | 2013 | 23638086 |
| diversity of the most commonly reported facultative symbionts in two closely-related aphids with different host ranges. | richness and abundance of facultative symbionts vary strongly with aphid species and genotype, symbiont strain, host plant, biogeography, and a number of abiotic factors. despite indications that aphids in the same ecological niche show similar levels of facultative symbiont richness, existing reports do not consider the potential role of host plants on aphid microbial community. little is known about how oligophagy and polyphagy may be influenced by secondary symbiont distribution, mainly becau ... | 2017 | 28620748 |
| vitellogenin and its receptor play essential roles in the development and reproduction of the brown citrus aphid, aphis (toxoptera) citricidus. | vitellogenin (vg) and its receptor (vgr) play a key role in the reproductive process and development of insects. aphids are a group of high-fecundity insect species with pseudoplacental viviparity, but the roles of their vg and vgr genes have not been investigated yet. the brown citrus aphid, aphis (toxoptera) citricidus, is a major insect pest of citrus and the main vector of citrus tristeza closterovirus. in this study, we identified and characterized these two genes, designated as acvg and ac ... | 2017 | 29226991 |
| functional characterization of two acetylcholinesterase genes in the brown citrus aphid, aphis (toxoptera) citricidus (kirkaldy), using heterologous expression and rna interference. | acetylcholinesterase (ache) is the primary target of organophosphate- and carbamate-based insecticides. we sequenced the full-length cdnas of two ache genes from the brown citrus aphid aphis (toxoptera) citricidus (kirkaldy). these two genes, tcace1 and tcace2, which encode tcache1 and tcache2, respectively, had a shared amino acid identity of 29% and were highly similar to other insect ace1 and ace2 genes, respectively, having specific functional motifs. potential differences in enzymatic funct ... | 2017 | 28456308 |
| silencing of two insulin receptor genes disrupts nymph-adult transition of alate brown citrus aphid. | insulin receptors play key roles in growth, development, and polymorphism in insects. here, we report two insulin receptor genes (acinr1 and acinr2) from the brown citrus aphid, aphis (toxoptera) citricidus. transcriptional analyses showed that acinr1 increased during the nymph-adult transition in alate aphids, while acinr2 had the highest expression level in second instar nymphs. acinr1 is important in aphid development from fourth instar nymphs to adults as verified by dsrna feeding mediated r ... | 2017 | 28230772 |
| differential expression of genes in the alate and apterous morphs of the brown citrus aphid, toxoptera citricida. | winged and wingless morphs in insects represent a trade-off between dispersal ability and reproduction. we studied key genes associated with apterous and alate morphs in toxoptera citricida (kirkaldy) using rnaseq, digital gene expression (dge) profiling, and rna interference. the de novo assembly of the transcriptome was obtained through illumina short-read sequencing technology. a total of 44,199 unigenes were generated and 27,640 were annotated. the transcriptomic differences between alate an ... | 2016 | 27577531 |
| molecular characterization, mrna expression and alternative splicing of ryanodine receptor gene in the brown citrus aphid, toxoptera citricida (kirkaldy). | ryanodine receptors (ryrs) play a critical role in regulating the release of intracellular calcium, which enables them to be effectively targeted by the two novel classes of insecticides, phthalic acid diamides and anthranilic diamides. however, less information is available about this target site in insects, although the sequence and structure information of target molecules are essential for designing new control agents of high selectivity and efficiency, as well as low non-target toxicity. he ... | 2015 | 26154764 |