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a small wolbachia protein directly represses phage lytic cycle genes in "candidatus liberibacter asiaticus" within psyllids.huanglongbing (hlb) is a severe disease of citrus caused by an uncultured alphaproteobacterium "candidatus liberibacter asiaticus" and transmitted by asian citrus psyllids (diaphorina citri). two prophage genomes, sc1 and sc2, integrated in "ca. liberibacter asiaticus" strain uf506 were described previously, and very similar prophages are found resident in the majority of "ca. liberibacter asiaticus" strains described worldwide. the sc1 lytic cycle is marked by upregulation of prophage late gene ...201728608866
ldtr is a master regulator of gene expression in liberibacter asiaticus.huanglongbing or citrus greening disease is causing devastation to the citrus industry. liberibacter asiaticus, an obligate intracellular pathogen of citrus, is one the causative agents of the disease. most of the knowledge about this bacterium has been deduced from the in silico exploration of its genomic sequence. l. asiaticus differentially expresses genes during its transmission from the psyllid vector, diaphorina citri, to the plant. however, the regulatory mechanisms for the adaptation of ...201728503858
acute toxicity of fresh and aged residues of pesticides to the parasitoid tamarixia radiata and to the hlb-bacteria vector diaphorina citri.one method for controlling the asian citrus psyllid (acp) diaphorina citri kuwayama, the vector of the putative causal agent of huanglongbing, uses the parasitoid tamarixia radiata (waterston). however, the general intensive use of insecticides has reduced the numbers of this parasitoid. this study evaluated the effect of the residual action of 24 insecticides on t. radiata and also determined the differential toxicity of insecticides to d. citri and t. radiata, using three bioassays. in the fir ...201729222706
neonicotinoid-induced mortality of diaphorina citri (hemiptera: liviidae) is affected by route of exposure.the use of neonicotinoids in citrus (rutaceae) has increased substantially to help manage the asian citrus psyllid, diaphorina citri kuwayama (hemiptera: liviidae), a vector of the devastating citrus disease, huanglongbing (hlb). in citrus pest management programs, neonicotinoids are most often applied to the soil as a drench and move through xylem channels from the roots into the foliage. we developed a novel assay to quantify the dose required to kill d. citri following ingestion and compare i ...201728961723
comprehensive meta-analysis, co-expression, and mirna nested network analysis identifies gene candidates in citrus against huanglongbing disease.huanglongbing (hlb), the most devastating disease of citrus, is associated with infection by candidatus liberibacter asiaticus (calas) and is vectored by the asian citrus psyllid (acp). recently, the molecular basis of citrus-hlb interactions has been examined using transcriptome analyses, and these analyses have identified many probe sets and pathways modulated by calas infection among different citrus cultivars. however, lack of consistency among reported findings indicates that an integrative ...201526215595
dynamics of huanglongbing-associated bacterium candidatus liberibacter asiaticus in citrus aurantifolia swingle (mexican lime).the bacterial disease citrus huanglongbing (hlb), associated with "candidatus liberibacter asiaticus" (c.las) has severely impacted the citrus industry, causing a significant reduction in production and fruit quality. in the present study, it was monitored the c.las population dynamics in symptomatic, hlb-positive mexican lime trees (citrus aurantifolia swingle) in a tropical, citrus-producing area of mexico. the objective of this study was to identify the dynamics of the population of huanglong ...201729023002
imidacloprid transport and sorption nonequilibrium in single and multilayered columns of immokalee fine sand.imidacloprid (imd) is a neonicotinoid pesticide soil-drenched to many crops to control piercing-sucking insects such as the asian citrus psyllid (acp). neonicotinoids are persistent in the environment and transport analyses are helpful estimate leaching potential from soils that could result in groundwater pollution. the objective of this study was to analyze imd breakthrough under saturated water flow in soil columns packed with three horizons (a, e, bh) of immokalee fine sand (ifs). also, we u ...201728837702
metabolic alterations in the nymphal instars of diaphorina citri induced by candidatus liberibacter asiaticus, the putative pathogen of huanglongbing.currently, huanglongbing is the most damaging disease of citrus causing huge economic losses. the disease is caused by the gram-negative bacterium candidatus liberibacter asiaticus (clas). the pathogen is transmitted in a persistent propagative circulative manner within its vector, the asian citrus psyllid, diaphorina citri. exploring the metabolic alteration in the vector may lead to a better understanding of the nutritional needs of clas and to designing an artificial medium for culturing the ...201829370262
insecticide resistance of adults and nymphs of asian citrus psyllid populations from apatzingán valley, mexico.control of the asian citrus psyllid diaphorina citri kuwayama, the most important pest of citrus worldwide, is based on the use of insecticides, though unsatisfactory results have recently been reported. in this study, insecticide resistance of d. citri to three insecticides (bifenthrin, malathion, and chlorpyrifos) was examined.201828719016
β-caryophyllene emitted from a transgenic arabidopsis or chemical dispenser repels diaphorina citri, vector of candidatus liberibacters.production of citrus, the main fruit tree crop worldwide, is severely threatened by huanglongbing (hlb), for which as yet a cure is not available. spread of this bacterial disease in america and asia is intimately connected with dispersal and feeding of the insect vector diaphorina citri, oligophagous on rutaceous host plants. effective control of this psyllid is an important component in successful hlb management programs. volatiles released from the non-host guava have been shown to be repelle ...201728717202
innate immune system capabilities of the asian citrus psyllid, diaphorina citri.citrus production worldwide is currently threatened by huanglongbing, or citrus greening disease. the associated pathogen, candidatus liberibacter asiaticus (clas), is transmitted by the asian citrus psyllid, diaphorina citri. annotation of the d. citri genome revealed a reduced innate immune system lacking a number of antimicrobial peptides and the imd pathway associated with defense against gram-negative bacteria. we characterized this apparent immune reduction in survival assays in which d. c ...201728624621
a plant pathogenic bacterium exploits the tricarboxylic acid cycle metabolic pathway of its insect vector.huanglongbing in citrus is caused by a phloem-limited, uncultivable, gram-negative α-proteobacterium, candidatus liberibacter asiaticus (clas). clas is transmitted by the phloem-sucking insect, diaphorina citri (hemiptera: liviidae), in a persistent, circulative, and propagative manner. in this study, we investigated the metabolomic and respiration rates changes in d. citri upon infection with clas using gas chromatography-mass spectrometry (gc-ms) and gas exchange analysis. the level of glycine ...028594267
delivery of dsrna through topical feeding for rna interference in the citrus sap piercing-sucking hemipteran, diaphorina citri.rna interference (rnai) is a powerful means to study functional genomics in insects. the delivery of dsrna is a challenging step in the development of rnai assay. here, we describe a new delivery method to increase the effectiveness of rnai in the asian citrus psyllid diaphorina citri. bromophenol blue droplets were topically applied to fifth instar nymphs and adults on the ventral side of the thorax between the three pairs of legs. in addition to video recordings that showed sucking of the brom ...201728585706
'candidatus liberibacter asiaticus' accumulates inside endoplasmic reticulum associated vacuoles in the gut cells of diaphorina citri.citrus greening disease known also as huanglongbing (hlb) caused by the phloem-limited bacterium 'candidatus liberibacter asiaticus' (clas) has resulted in tremendous losses and the death of millions of trees worldwide. clas is transmitted by the asian citrus psyllid diaphorina citri. the closely-related bacteria 'candidatus liberibacter solanacearum' (clso), associated with vegetative disorders in carrots, is transmitted by the carrot psyllid bactericera trigonica. a promising approach to preve ...201729208900
economic injury levels for asian citrus psyllid control in process oranges from mature trees with high incidence of huanglongbing.the asian citrus psyllid (acp), diaphorina citri kuwayama, is the key pest of citrus wherever it occurs due to its role as vector of huanglongbing (hlb) also known as citrus greening disease. insecticidal vector control is considered to be the primary strategy for hlb management and is typically intense owing to the severity of this disease. while this approach slows spread and also decreases severity of hlb once the disease is established, economic viability of increasingly frequent sprays is u ...201728426676
rna interference of acetylcholinesterase in the asian citrus psyllid, diaphorina citri, increases its susceptibility to carbamate and organophosphate insecticides.the asian citrus psyllid, diaphorina citri kuwayama (hemiptera: lividae) transmits the candidatus liberibacter asiaticus, which causes citrus greening disease or huanglongbing, (hlb). to date, there is no efficient cure for hlb disease and the control of d. citri using insecticides became the most important tools for the management of hlb. however, the extensive use of insecticides could increase d. citri resistance to these insecticides. the objective of this study was to investigate the effect ...201729183615
the control of invasive species on private property with neighbor-to-neighbor spillovers.invasive pests cross property boundaries. property managers may have private incentives to control invasive species despite not having sufficient incentive to fully internalize the external costs of their role in spreading the invasion. each property manager has a right to future use of his own property, but his property may abut others' properties enabling spread of an invasive species. the incentives for a foresighted property manager to control invasive species have received little attention. ...201425346573
vector control and foliar nutrition to maintain economic sustainability of bearing citrus in florida groves affected by huanglongbing.huanglongbing (hlb) or citrus greening is a bacterial disease vectored by the asian citrus psyllid (acp) causing tree decline, and yield loss. vector control and foliar nutrition are used in florida to slow the spread of hlb and mitigate debilitating effects of the disease. a four year replicated field study was initiated february 2008 in a 5.2-ha commercial block of young 'valencia' orange trees employing a factorial design to evaluate individual and compound effects of vector management and fo ...201423666807
compatibility and efficacy of isaria fumosorosea with horticultural oils for mitigation of the asian citrus psyllid, diaphorina citri (hemiptera: liviidae).horticultural oils are an important component of integrated management programs of several phytophagous arthropods and pathogens affecting fruit, ornamentals and vegetables in greenhouse and field production systems. although effective against the target pest, their incompatibility with biological control agents can compromise efforts to develop eco-friendly management programs for important agricultural pests. in this study, we assessed the in vitro effect of selected refined petroleum oils use ...201729088086
rna interference of two glutathione s-transferase genes, diaphorina citri dcgste2 and dcgstd1, increases the susceptibility of asian citrus psyllid (hemiptera: liviidae) to the pesticides fenpropathrin and thiamethoxam.the asian citrus psyllid, diaphorina citri kuwayama, is an important agricultural pest of citrus globally. foliar application of chemical insecticides is the most widely used option for reducing d. citri populations. knockdown of glutathione s-transferase (gst) in several insect species leads to increased susceptibility to insecticides; however, information about the detoxifying role of gst genes in d. citri is unavailable.201728971568
selection of reference genes for expression studies in diaphorina citri (hemiptera: liviidae).the asian citrus psyllid, diaphorina citri kuwayama (hemiptera: liviidae), is considered the main vector of the bacteria associated with huanglongbing, a very serious disease that has threatened the world citrus industry. the absence of efficient control management protocols, including a lack of resistant cultivars, has led to the development of different approaches to study this pathosystem. the production of resistant genotypes relies on d. citri gene expression analyses by rt-qpcr to assess c ...201729029285
population genetic structure of diaphorina citri kuwayama (hemiptera: liviidae): host-driven genetic differentiation in china.the asian citrus psyllid diaphorina citri kuwayama is a major pest in citrus production, transmitting candidatus liberibacter asiaticus. it has spread widely across eastern and southern china. unfortunately, little is known about the genetic diversity and population structure of d. citri, making pest control difficult. in this study, nine specifically developed ssr markers and three known mitochondrial dna were used for population genetics study of d. citri using 225 samples collected from all 7 ...201829367741
contrasting amino acid profiles among permissive and non-permissive hosts of candidatus liberibacter asiaticus, putative causal agent of huanglongbing.huanglongbing is a devastating disease of citrus. in this study, a comprehensive profile of phloem sap amino acids (aa) in four permissive host plants of candidatus liberibacter asiaticus (clas) and three non-permissive rutaceae plants was conducted to gain a better understanding of host factors that may promote or suppress the bacterium. the aa profiles of diaphorina citri nymphs and adults were similarly analyzed. a total of 38 unique aas were detected in phloem sap of the various plants and d ...201729236706
concomitant loss of the glyoxalase system and glycolysis makes the uncultured pathogen "candidatus liberibacter asiaticus" an energy scavenger.methylglyoxal (mg) is a cytotoxic, non-enzymatic byproduct of glycolysis that readily glycates proteins and dna, resulting in carbonyl stress. glyoxalase i and ii (gloa and glob) sequentially convert mg into d-lactic acid using glutathione (gsh) as a cofactor. the glyoxalase system is essential for the mitigation of mg-induced carbonyl stress, preventing subsequent cell death, and recycling gsh for maintenance of cellular redox poise. all pathogenic liberibacters identified to date are unculture ...201728939611
resistance management for asian citrus psyllid, diaphorina citri kuwayama, in florida.the asian citrus psyllid, diaphorina citri kuwayma, is one of the most important pests in citrus production. the objective of this study was to evaluate d. citri resistance management with three insecticide rotations and compare them with no rotation and an untreated check. the different insecticides (modes of action) tested were: dimethoate, imidacloprid, diflubenzuron, abamectin 3% + thiamethoxam 13.9%, and fenpropathrin. eggs, nymph, and adult psyllids were counted weekly. five insecticide ap ...201728930170
wavelength and polarization affect phototaxis of the asian citrus psyllid.the asian citrus psyllid, diaphorina citri kuwayama (hemiptera: liviidae), is a primary pest of citrus due to its status as a vector of the citrus disease, huanglongbing. we evaluated the effects of light of specific wavelength and polarization on phototactic behavior of d. citri using a horizontal bioassay arena. wavelength-associated positive phototaxis was associated with short wavelength uv (350-405 nm) targets whereas little or no responses were seen in longer wavelength targets in the visi ...201728825636
the candidatus liberibacter-host interface: insights into pathogenesis mechanisms and disease control."candidatus liberibacter" species are associated with economically devastating diseases of citrus, potato, and many other crops. the importance of these diseases as well as the proliferation of new diseases on a wider host range is likely to increase as the insects vectoring the "ca. liberibacter" species expand their territories worldwide. here, we review the progress on understanding pathogenesis mechanisms of "ca. liberibacter" species and the control approaches for diseases they cause. we di ...201728637377
an assessment of interspecific competition between two introduced parasitoids of diaphorina citri (hemiptera: liviidae) on caged citrus plants.two parasitoids attacking nymphs of asian citrus psyllid, diaphorina citri kuwayama (hemiptera: liviidae), tamarixia radiata (waterston) (hymenoptera: eulophidae) and diaphorencyrtus aligarhensis (shafee, alam & agarwal) (hymenoptera: encyrtidae) are being released in california, usa in a classical biological control program. to evaluate the effect of multiple parasitoid species on d. citri mortality, we conducted mesocosm experiments under controlled conditions using a complete block design wit ...201728590080
susceptibility of diaphorina citri (hemiptera: liviidae) and its parasitoid tamarixia radiata (hymenoptera: eulophidae) to entomopathogenic fungi under laboratory conditions.diaphorina citri (kuwayama) is a global pest of citrus that transmits the bacteria associated with the disease, huanglongbing. entomopathogenic fungi and the parasitoid tamarixia radiata (waterston) are important biological control agents of this pest and likely to interact in d. citri populations. as a basis for interaction studies, we determined the susceptibility of nymphs and adults of d. citri and adults of the parasitoid t. radiata to six fungal isolates from the species beauveria bassiana ...201728721609
sperm morphology of the leafhopper diaphorina citri kuwayama (hemiptera: sternorrhyncha: psylloidea: liviidae).in this study, by using light and electron microscopy, we describe the sperm morphology of the leafhopper diaphorina citri, a serious pest of citrus throughout the world. in this species the sperm measures 538.49±8.75μm in length, and as observed in psylloids, the sperm, when manipulated, opens into two filaments, one of which is attached to the nuclear base and the other becomes free. along the flagellum, and only of it, there are lateral projections, about 2μm in length. furthermore, at the en ...201728431332
occurrence of free fatty acids in the phloem sap of different citrus varieties.candidatus liberibacter asiaticus is a phloem restricted bacterium causes citrus greening disease or huanglongbing (hlb), a major treat to commercial citrus production in florida. it is transmitted by the asian citrus psyllid, a phloem sap-feeding insect. studies conducted on the composition of citrus phloem sap revealed the presence amino acids, organic acids and sugars and of low amounts of free fatty acids. in the present study, the phloem sap of twelve citrus varieties with different degrees ...028532234
tale of the huanglongbing disease pyramid in the context of the citrus microbiome.the huanglongbing (hlb) disease pyramid is composed of liberibacters, psyllid vectors, citrus hosts, and the environment. the epidemiological outcomes for liberibacter-associated plant diseases are collectively determined by the inherent relationships among plant-liberibacters-psyllids, and how various environmental factors affect plant-liberibacter-psyllid interactions. citrus-liberibacter-psyllid interactions occur in a complex microbiome system. in this review, we focus on the progress in und ...201728095208
induced preference improves offspring fitness in a phytopathogen vector.in the asian citrus psyllid (diaphorina citri kuwayama), learning facilitates host recognition and mate preference; however, it is unclear whether induced female oviposition preference occurs in this species. we investigated the influence of natal host experience on adult oviposition preference when reared on either 'valencia' orange (citrus x sinesis) or orange jasmine (murraya paniculata). psyllids reared on 'valencia' orange preferred 'valencia' orange as an oviposition host compared with ora ...201728961753
metabolomic response to huanglongbing: role of carboxylic compounds in citrus sinensis response to 'candidatus liberibacter asiaticus' and its vector, diaphorina citri.huanglongbing, a destructive disease of citrus, is caused by the fastidious bacterium 'candidatus liberibacter asiaticus' and transmitted by asian citrus psyllid, diaphorina citri. the impact of 'ca. l. asiaticus' infection or d. citri infestation on valencia sweet orange (citrus sinensis) leaf metabolites was investigated using gas chromatography mass spectrometry, followed by gene expression analysis for 37 genes involved in jasmonic acid (ja), salicylic acid (sa), and proline-glutamine pathwa ...201728510485
modeling the phenology of asian citrus psyllid (hemiptera: liviidae) in urban southern california: effects of environment, habitat, and natural enemies.modeling can be used to characterize the effects of environmental drivers and biotic factors on the phenology of arthropod pests. from a biological control perspective, population dynamics models may provide insights as to when the most vulnerable pest life stages are available for natural enemies to attack. analyses presented here used temperature and habitat dependent, instar-specific, discrete models to investigate the population dynamics of asian citrus psyllid, diaphorina citri kuwayama (he ...201829373671
putative sex pheromone of the asian citrus psyllid, diaphorina citri, breaks down into an attractant.under laboratory conditions, mating activity in asian citrus psyllid (acp) started 4 days after emergence, peaked at day 7, and showed a clear window of activity starting 8 h into the photophase and extending through the first hour of the scotophase. we confirmed that acp males are attracted to emanations from conspecific females. traps loaded with a candidate compound enriched with female extract, lignoceryl acetate (24ac), at various doses were active only after being deployed for several week ...201829323263
global mtdna genetic structure and hypothesized invasion history of a major pest of citrus, diaphorina citri (hemiptera: liviidae).the asian citrus psyllid diaphorina citri kuwayama is a key pest of citrus as the vector of the bacterium causing the "huanglongbing" disease (hlb). to assess the global mtdna population genetic structure, and possible dispersal history of the pest, we investigated genetic variation at the coi gene collating newly collected samples with all previously published data. our dataset consists of 356 colonies from 106 geographic sites worldwide. high haplotype diversity (h-mean = 0.702 ± 0.017), low n ...201829321868
diaphorina citri nymphs are resistant to morphological changes induced by "candidatus liberibacter asiaticus" in midgut epithelial cells."candidatus liberibacter asiaticus" is the causative bacterium associated with citrus greening disease. "ca. l. asiaticus" is transmitted by diaphorina citri more efficiently when it is acquired by nymphs rather than adults. why this occurs is not known. we compared midguts of d. citri reared on healthy or "ca. l. asiaticus"-infected citrus trees using quantitative pcr, confocal microscopy, and mitochondrial superoxide staining for evidence of oxidative stress. consistent with its classification ...201829311247
citrus flush shoot ontogeny modulates biotic potential of diaphorina citri.the biology and behaviour of the psyllid diaphorina citri kuwayama (hemiptera: sternorrhyncha: liviidae), the major insect vector of bacteria associated with huanglongbing, have been extensively studied with respect to host preferences, thermal requirements, and responses to visual and chemical volatile stimuli. however, development of the psyllid in relation to the ontogeny of immature citrus flush growth has not been clearly defined or illustrated. such information is important for determining ...201829304052
genetic variation and potential co-infection of wolbachia among widespread asian citrus psyllid (diaphorina citri kuwayama) populations.wolbachia can profoundly influence the survival, reproduction, and defenses of insect hosts. these interactions could potentially be harnessed for managing pests or insect-transmitted diseases. diaphorina citri kuwayama is a phloem-feeding pest capable of transmitting the putative causal agent of citrus greening, candidatus liberibacter asiaticus (clas). like many insects, d. citri is also infected with wolbachia (wdi). recent studies indicate that the relative abundance of wdi could be associat ...201729286204
behavior of bacteriome symbionts during transovarial transmission and development of the asian citrus psyllid.the asian citrus psyllid diaphorina citri kuwayama (hemiptera: liviidae) is a serious pest worldwide, transmitting candidatus liberibacter spp. (alphaproteobacteria), the causative agents of a devastating citrus disease known as huanglongbing or greening disease. in a symbiotic organ called the bacteriome, d. citri possesses an organelle-like defensive symbiont, candidatus profftella armatura (betaproteobacteria), and a nutritional symbiont, ca. carsonella ruddii (gammaproteobacteria). drastical ...201729240843
evidence of behavior-based utilization by the asian citrus psyllid of a combination of uv and green or yellow wavelengths.the asian citrus psyllid, diaphorina citri, vectors huanglongbing (hlb), the most serious disease affecting citrus globally. d. citri and hlb have spread to the major citrus growing regions of north america causing billions of dollars of damage in florida alone. the visual behavior of d. citri is not well characterized and more knowledge is needed to improve attractive traps for monitoring and control of the d. citri. bioassays were conducted to evaluate attraction to light transmitted through d ...201729236740
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