Glassy-winged Sharpshooter Research Articles

Models Applied to Grapevine Pests: A Review.

Simple SummaryMathematical models are developed to predict key aspects of insects harmful to many crops, including grapevine. Practical applications of these models include forecasting seasonal occurrence and spread over space in order to make decisions about pest management (e.g., timing of insecticide sprays). Many models have recently been developed to evaluate the spread of insect pests on grapevine under a climate change scenario as well as to forecast the possibility that alien species could settle into new environments. To make the published models available to vine-growers and their stakeholders, a holistic approach presenting these models within the frame of a decision support system should be followed.This paper reviews the existing predictive models concerning insects and mites harmful to grapevine. A brief conceptual description is given on the definition of a model and about different types of models: deterministic vs. stochastics, continuous vs. discrete, analytical vs. computer-based, and descriptive vs. data-driven. The main biological aspects of grapevine pests covered by different types of models are phenology, population growth and dynamics, species distribution, and invasion risk. A particular emphasis is put on forecasting epidemics of plant disease agents transmitted by insects with sucking-piercing mouthparts. The most investigated species or groups are the glassy-winged sharpshooter Homalodisca vitripennis (Germar) and other vectors of Xylella fastidiosa subsp. fastidiosa, a bacterium agent of Pierce’s disease; the European grape berry moth, Lobesia botrana (Denis and Schiffermuller); and the leafhopper Scaphoideus titanus Ball, the main vector of phytoplasmas agents of Flavescence dorée. Finally, the present and future of decision-support systems (DSS) in viticulture is discussed.

Insecticide resistance in California populations of the glassy-winged sharpshooter Homalodisca vitripennis.

The glassy-winged sharpshooter, Homalodisca vitripennis (Germar), is a primary vector of Pierce's disease of grapes in California. Systemic imidacloprid treatments have been the mainstay of area-wide treatment programs that were established in the Central Valley (Kern and Tulare Counties) and Southern California (Riverside County) during the 1990s to combat the pest. The programs helped to suppress populations on citrus, a major sharpshooter host, to levels that significantly reduced migration into adjacent vineyards. However, beginning in 2012, there has been a resurgence of glassy-winged sharpshooter populations in Kern and Tulare counties, and hitherto successful treatment strategies have not been as effective. This study investigated the possibility that insecticide resistance was a contributing factor to the population resurgence. Topical application bioassays detected high levels of resistance to imidacloprid in Kern and Tulare populations, and lower levels of resistance (perhaps due to cross-resistance) to the foliar neonicotinoid acetamiprid (20-fold), the pyrethroid fenpropathrin (7.4-fold), and the butenolide flupyradifurone (4-fold). Samples of glassy-winged sharpshooters from citrus groves under organic management also exhibited high levels of imidacloprid resistance. The long-term use of imidacloprid has selected for resistance in glassy-winged sharpshooters. The most resistant populations also exhibited resistance to the foliar neonicotinoid acetamiprid, the pyrethroid fenpropathrin, and the butenolide flupyradifurone. High levels of imidacloprid resistance in insects sampled from organic groves indicate that resistant insects are migrating from nearby conventional groves, which could compromise the control of sharpshooters in organic systems with insecticides affected by cross-resistance. © 2021 Society of Chemical Industry.

Control of Pierce’s Disease Through Areawide Management of Glassy-Winged Sharpshooter (Hemiptera: Cicadellidae) and Roguing of Infected Grapevines

AbstractThe General Beale Pilot Project serves as a case study for the use of areawide monitoring and treatment programs for glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), and monitoring and roguing programs for grapevines infected with Xylella fastidiosa, to achieve regional management of Pierce’s disease. The Project is located in southeast Kern County, CA, and contains ~2,800 ha of citrus and grapevines grown within approximately 50 km2. For nearly 20 yr, an average of 470 traps have been used to monitor GWSS populations regionally by the California Department of Food and Agriculture, and to inform coordinated, areawide treatments by the USDA-APHIS Areawide Treatment Program to overwintering GWSS in citrus. Grape growers were responsible for treating their own vineyards, and for the roguing of infected grapevines based on surveys provided by the University of California. Herein, we provide a history of the General Beale Pilot Project, broken down into six eras based on levels of Project success, which incorporate data on GWSS captures, pesticide use, and disease incidence. We describe patterns of success related to the regional coordination of effective treatment and roguing programs that can be used by grape and neighboring citrus growers for areawide management of Pierce’s disease. We conclude by describing current and future challenges for Pierce’s disease management, including pesticide availability and resistance, GWSS refuges, the inability to detect and rogue infected vines in the year they become infected, and the sustainability of voluntary programs that rely on public funding.

Xylella fastidiosa and Glassy-Winged Sharpshooter Population Dynamics in the Southern San Joaquin Valley of California.

Xylella fastidiosa is a vector-transmitted bacterial plant pathogen that affects a wide array of perennial crops, including grapevines (Pierce's disease). In the southern San Joaquin Valley of California, epidemics of Pierce's disease of grapevine were associated with the glassy-winged sharpshooter, Homalodisca vitripennis. During the growing season, rates of X. fastidiosa spread in vineyards are affected by changes in pathogen distribution within chronically infected grapevines and by vector population dynamics. Grapevines chronically infected with X. fastidiosa rarely tested positive for the pathogen prior to July, suggesting vector acquisition of X. fastidiosa from grapevines increases as the season progresses. This hypothesis was supported by an increase in number of X. fastidiosa-positive glassy-winged sharpshooters collected from vineyards during July through September. Analysis of insecticide records indicated that vineyards in the study area were typically treated with a systemic neonicotinoid in spring of each year. As a result, abundance of glassy-winged sharpshooters was typically low in late spring and early summer, with abundance of glassy-winged sharpshooter adults increasing in late June and early July of each year. Collectively, the results suggest that late summer is a crucial time for X. fastidiosa secondary spread in vineyards in the southern San Joaquin Valley, because glassy-winged sharpshooter abundance, number of glassy-winged sharpshooters testing positive for X. fastidiosa, and grapevines with detectable pathogen populations were all greatest during this period.

Symbiont replacements reset the co-evolutionary relationship between insects and their heritable bacteria.

Auchenorrhynchan insects (Hemiptera) generally depend on two bacterial symbionts for nutrition. These bacteria experience extreme genome reduction and loss of essential cell functions that require direct host support, or the replacement of failing symbionts with more capable ones. However, it remains unclear how hosts adapt to integrate symbionts into their systems, particularly when they are replaced. Here, we comparatively investigated the evolution of host-support mechanisms in the glassy-winged sharpshooter, Homalodisca vitripennis (GWSS), and the aster leafhopper, Macrosteles quadrilineatus (ALF). ALF harbors the ancestral co-symbionts of the Auchenorrhyncha that have tiny genomes, Sulcia (190 kb) and Nasuia (112 kb). In GWSS, Sulcia retains an expanded genome (245 kb), but Nasuia was replaced by the more capable Baumannia (686 kb). To support their symbionts, GWSS and ALF have evolved novel mechanisms via horizontal gene transfer, gene duplication, and co-option of mitochondrial support genes. However, GWSS has fewer support systems targeting essential bacterial processes. In particular, although both hosts use ancestral mechanisms to support Sulcia, GWSS does not encode all of the same support genes required to sustain Sulcia-ALF or Nasuia. Moreover, GWSS support of Baumannia is far more limited and tailored to its expanded capabilities. Our results demonstrate how symbiont replacements shape host genomes and the co-evolutionary process.

Targeted Mutations in Xylella fastidiosa Affect Acquisition and Retention by the Glassy-Winged Sharpshooter, Homalodisca vitripennis (Hemiptera: Cicadellidae).

Xylella fastidiosa (Wells) is a xylem-limited bacterium that causes Pierce's disease of grapevines. The bacterium is transmitted by insect vectors such as the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar). Experiments were conducted to compare the role of selected X. fastidiosa genes on 1) bacterial acquisition and retention in GWSS foreguts, and 2) transmission to grapevines by GWSS. Bacterial genotypes used were: mutants Xf-ΔpilG, Xf-ΔpilH, Xf-ΔgacA, and Xf-ΔpopP; plus wild type (WT) as control. Results showed that Xf-ΔpilG had enhanced colonization rate and larger numbers in GWSS compared with WT. Yet, Xf-ΔpilG exhibited the same transmission efficiency as WT. The Xf-ΔpilH exhibited poor acquisition and retention. Although initial adhesion, multiplication, and retention of Xf-ΔpilH in GWSS were almost eliminated compared with WT, the mutation did not reduce transmission success in grapevines. Overall, Xf-ΔgacA showed colonization rates and numbers in foreguts similar to WT. The Xf-ΔgacA mutation did not affect initial adhesion, multiplication, and long-term retention compared with WT, and was not significantly diminished in transmission efficiency. In contrast, numbers of Xf-ΔpopP were variable over time, displaying greatest fluctuation from highest to lowest levels. Thus, Xf-ΔpopP had a strong, negative effect on initial adhesion, but adhered and slowly multiplied in the foregut. Again, transmission was not diminished compared to WT. Despite reductions in acquisition and retention by GWSS, transmission efficiency of genotypes to grapevines was not affected. Therefore, in order to stop the spread of X. fastidiosa by GWSS using gene-level targets, complete disruption of bacterial colonization mechanisms is required.

The mitochondrial genome of Cofana yasumatsui (Hemiptera: Cicadellidae: Cicadellinae)

The complete mitochondrial genome of Cofana yasumatsui (Hemiptera: Cicadellidae: Cicadellinae) is sequenced. Based on annotation, the mitochondrial genome is 15,019 bp, has an A + T content of 77.2% (A = 42.0%, T = 35.2%, G = 10.0%, C = 12.8%), which is the classical structure for insect mitogenome. All PCGs started with ATN, except ATP8 and ND5 starting with TTG. All PCGs used TAN as stop codon, except ND5 stopping with single T. The phylogenetic relationship of C. yasumatsui clustered together with Cicadella viridis, Homalodisca coagulata, Homalodisca vitripennis, and Bothrogonia ferruginea from Cicadellinae. This is identical with the result of the traditional taxonomy.

Transmission of Pantoea agglomerans—A paratransgenic control agent—Within a Homalodisca vitripennis population

AbstractParatransgenic control of pests can be an alternative to chemical control, which is associated with environmental contamination, and higher input cost. We have recently developed paratransgenic control strategy to block transmission of the Pierce's disease pathogen—Xylella fastidiosa by its arthropod vector—Homalodisca vitripennis (the glassy‐winged sharpshooter) using antimicrobial peptide‐expressing strains of Pantoea agglomerans. In the present study, we report horizontal transmission of one of such P. agglomerans strains from H. vitripennis. This process indicates that P. agglomerans can self‐sustain in a population of H. vitripennis and, thus, can provide paratransgenic control of X. fastidiosa in field. These results also provide basis for future field studies.

Infection of Blueberry Cultivar 'Emerald' with a California Pierce's Disease Strain of Xylella fastidiosa and Acquisition by Glassy-Winged Sharpshooter.

Bacterial leaf scorch disease caused by Xylella fastidiosa occurs in southern highbush blueberry varieties in the southeastern United States. Susceptibility to X. fastidiosa varies by blueberry cultivar, and these interactions are often strain-specific. Xylella fastidiosa subsp. fastidiosa is the causal agent of Pierce's disease in grapevines, and it has been problematic in the San Joaquin Valley of California since the introduction of the glassy-winged sharpshooter (Homalodisca vitripennis). The glassy-winged sharpshooter is known to feed on blueberry, a crop that is expanding in the San Joaquin Valley. Currently, little is known about the potential for the spread of X. fastidiosa between grape and blueberry in this region. The ability of a Pierce's disease strain of X. fastidiosa from the San Joaquin Valley to cause disease in southern highbush blueberry and the potential for the glassy-winged sharpshooter to transmit X. fastidiosa between blueberry and grapevine were investigated. Experimental inoculations showed that the X. fastidiosa subsp. fastidiosa strain Bakersfield-1 can cause disease in blueberry cv. Emerald, and that the glassy-winged sharpshooter can acquire X. fastidiosa from artificially inoculated blueberry plants under laboratory conditions. Understanding the possibility for X. fastidiosa strains from the San Joaquin Valley to infect multiple crops grown in proximity is important for area-wide pest and disease management.

Transmission of the frequency components of the vibrational signal of the glassy-winged sharpshooter, Homalodisca vitripennis, within and between grapevines

The agricultural pest, Homalodisca vitripennis, relies on vibrational communication through plants for species identification, location, and courtship. Their vibrational signal exhibits a dominant frequency between 80 and 120 Hz, with higher frequency, lower intensity harmonics occurring approximately every 100 Hz. However, previous research revealed that not all harmonics are recorded in every signal. Therefore, how the female H. vitripennis vibrational signal changes as it travels through the plant was investigated. Results confirmed that transmission was a bending wave, with decreased signal intensity for increasing distance from the source; moreover, at distances of 50 cm, higher frequencies traveled faster than lower frequencies, suggesting that dispersion of H. vitripennis signal components may enable signaling partners to encode distance. Finally, H. vitripennis generates no detectable airborne signal (pressure wave), yet their low vibrational frequency components are detectable in neighboring plants as a result of leaf-to-air-to-leaf propagation. For instance, with isolated key female signal frequencies, 100 Hz was detected at a 10 cm gap between leaves, whereas 600 Hz was detectable only with a 0.1 cm gap. Together, these results highlight the complexity of vibration propagation in plants and suggest the possibility of the animals using the harmonic content to determine distance to the signaling H. vitripennis source.

Current and planned research for managing the risk of <i>Xylella fastidiosa </i>to New Zealand

Xylella fastidiosa (Xf), a xylem-limited bacterium native to the Americas, has a devastating impact on many crops internationally. In California, Xf causes over USD 100 million in yearly losses to the grape industry and infects an estimated 200 million citrus trees in Brazil. More recently, Xf killed around one million olive trees on the Italian peninsula of Salento. Xylella fastidiosa is not known to be present in New Zealand. The glassy-winged sharpshooter (Homalodisca vitripennis), an important vector of Xf in California, is also not present in New Zealand. However, the meadow spittle bug (Philaenus spumarius), an important vector of Xf in Italy, is present. Many economically important horticultural, viticultural, agricultural, amenity and indigenous/native plant species, including taonga, are likely to be susceptible to Xf. Aspects of our research on Xf to understand the impact, reduce the likelihood of entry into New Zealand and/or minimising its impact in New Zealand will be presented. The research listed on the poster spans risk assessment, diagnostics, surveillance and biological control but could certainly be increased across the biosecurity continuum given the magnitude of the threat from Xf to New Zealand’s valuable plant systems.

Pest categorisation of non-EU Cicadomorpha vectors of Xylella spp.

The Panel on Plant Health performed a group pest categorisation of non‐EU Cicadomorpha vectors of Xylella spp. known to be associated with plant diseases. Although all the insects considered in this categorisation are proven vectors of Xylella spp., additional vectors within the order Hemiptera most probably exist but have not been associated with any Xylella spp. disease yet. Currently, the group consists of 50 taxa (49 at species level and one at genus level) from the families Aphrophoridae, Cicadellidae and Membracidae (Arthropoda: Hemiptera: Cicadomorpha) for which reliable identification methods exist. Members of the group can be found in the Americas, Asia, Africa and Oceania. Only one of them, Homalodisca vitripennis is considered invasive. Species in the group are mostly polyphagous; many are known to feed on several plant families. Hosts can include broadleaf trees, herbaceous plants and grasses. Breeding takes place on herbaceous hosts and eggs are inserted into plant tissues. Nymphs emerge to feed on sap of the natal host. Adults move from breeding hosts to food hosts and can spread Xylella spp. causing a variety of diseases. Three of the species are listed in Annex IAI of Council Directive 2000/29/EC as examples of Cicadellidae (non‐EU) known to be vector of Pierce's disease (caused by Xylella fastidiosa). Plants for planting, cut branches, flowers and fruit are potential pathways for entry into the EU. However, there are no records of EU interceptions of any members of the group. EU biotic and abiotic conditions are conducive for establishment and spread of these insects. Were members of the group to establish and spread, impact on several cultivated species (e.g. grapevine, citrus, Prunus spp.) and ornamentals (e.g. Polygala myrtifolia) could be expected as these insect species are efficient vectors of Xylella spp. Considering the criteria within the remit of EFSA to assess their regulatory plant health status, the group of non‐EU Cicadomorpha vectors of Xylella spp. meets all the criteria assessed by EFSA for consideration as potential Union quarantine pests. The group does not meet all the criteria assessed by EFSA for consideration as regulated non‐quarantine pests, as members of the group are not present in the EU.

Individual field-collected glassy-winged sharpshooter vectors harbor sequences from two Xylella fastidiosa subspecies

During 2016 and 2017, glassy-winged sharpshooters (GWSS; Homalodisca vitripennis) collected from vineyards with a known history of Pierce’s disease or nearby citrus orchards in Kern County, California were assessed for presence of Xylella fastidiosa by quantitative PCR using total DNA samples extracted from GWSS heads. Conventional PCR products for three X. fastidiosa housekeeping genes (petC, leuA, and holC) were cloned from a subset of X. fastidiosa-positive GWSS DNA samples. Cloned sequences were assigned to X. fastidiosa subspecies based on Single Nucleotide Polymorphism (SNP) signature barcodes (7–12 polymorphic sites per amplicon that differentiate reference genomes of subspecies fastidiosa and multiplex). A total of 2005 clones were sequenced: 1499 (74.8%) were genotyped as subspecies fastidiosa and 491 (24.5%) as subspecies multiplex. Among cloned subspecies fastidiosa sequences, 95.4% had SNP barcodes identical to the corresponding gene present in subspecies fastidiosa strains cultured from Pierce’s disease-affected vines in the same region sampled in 2016 and 2017. Presence of SNP barcodes representing both subspecies in one or more cloned genes was commonly observed within individual GWSS. This observation indicates that populations of X. fastidiosa in some insects consists of two subspecies or of two genotypes of one subspecies in which a proportion of the population was derived from a lineage with a history of horizontal gene transfer and homologous recombination. These conclusions suggest that: 1) individual GWSS may visit multiple host species (inoculum sources); 2) sequential pathogen acquisition events can lead to co-colonization of GWSS; 3) competitive exclusion of X. fastidiosa in the foregut is weak or not operating; and 4) the vector foregut is a potential arena for exchange of genetic material among sympatric X. fastidiosa subspecies.

BAPC‐assisted‐CRISPR‐Cas9 Delivery into Nymphs and Adults for Heritable Gene Editing (Hemiptera)

New method for heritable gene editing in Insects, Hemiptera. Addition of Branched Amphiphilic Peptide Capsules, BAPC, improves delivery of CRISPR components, plasmids, and dsRNA for heritable gene editing and gene targeting in insect nymphs and adults (Psyllids- Diaphorina citri, Leafhoppers- Homalodisca vitripennis, Whitefly- Bemisia argentifolii). First heritable gene Knockouts, KO, using BAPC-assisted-CRISPR-Cas9, produced G2 mutants from injected adult females. The KO target was the thioredoxin gene, resulting in 550 nt deletion in gDNA of target insects. In psyllids the thioredoxin gene, TXT, and Vermillion, Vm, KO produced changes in physiology and eye color, respectively. Strategies are alter the insect vectors from vector into non-vectors. Psyllids transmit pathogenic bacteria, Liberibacter asiaticus, which threatens citrus worldwide, Leafhoppers transmit, Xylella fastidiosa, bacteria, which threatens tree crops and grapevines worldwide; Whiteflies transmit Begomovirus, which threaten global food security. Previous attempts with embryonic injections failed. To bypass the problem we used BAPC with CRISPR components injected in 3rd – 5th instars, and adult females near ovaries. One function of TXT is to promote development. The result is slower development, reduced lifespan, and reduce fecundity as observed in TXT-KO psyllid mutants. Reduce fecundity and slow development are traits that would reduce insect populations. Parasitoids and predators would also have more time to attack nymphal stages as pests take 2 to 3 weeks longer to go from egg to adult. Emerging adults have a reduced lifespan. For the Vm-KO, eye phenotype had color break, white regions. The BAPC-assisted delivery system advances gene editing efforts across all hemipteran pests by permitting the use of nymphs and adults. BAPC-assisted CRISPR delivery revolutionizes strategies to protect citrus and food crops from insect vectors and pathogens [citrusgreening.org]. Support or Funding Information Funding in part: USDA-NIFA 2014-70016-23028. Developing an Infrastructure and Product Test Pipeline to Deliver Novel Therapies for Citrus Greening Disease. Micro-CT scan of Adult Female Psyllid (Alba-Tercedor & Hunter 2016) This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sharpshooters, Leafhoppers, Cicadellidae (Insecta: Hemiptera: Auchenorrhyncha: Cicadellidae)

Sharpshooter is a term commonly used to describe a group of leafhoppers in the family Cicadellidae. There have been several explanations for the use of this term. Riley and Howard (1893) first used 'sharpshooter' to describe the feeding damage of the glassy-winged sharpshooter, Homalodisca coagulata (Say), on cotton. This damage was caused by the piercing-sucking mouthparts of H. coagulata that appeared to be caused by a 'minute bullet.' They also reported 'rapid and forcible ejection of minute drops of fluid' as another explanation for the use of this term. The term sharpshooter is also attributed to the hiding behavior of these insects when alarmed. Disturbed sharpshooters will slip quickly behind branches and stems to avoid predators, an action not unlike the behavior of army sharpshooter riflemen who would hide behind the trunks of trees to avoid detection by the opposition as they passed by their position. This document is EENY-334 , one of a series of Featured Creatures from the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Published: October 2004.
 EENY-334/IN611: Sharpshooters, Leafhoppers, Cicadellidae (Insecta: Hemiptera: Auchenorrhyncha: Cicadellidae) (ufl.edu)

Understanding How an Invasive Vector Drives Pierce's Disease Epidemics: Seasonality and Vine-to-Vine Spread.

For vector-borne plant pathogens, disease epidemics may be attributable to multiple mechanisms, including introduction of a novel vector whose epidemiological role differs from that of native vectors. In such cases, understanding an exotic vector's ability to drive an epidemic is central to mitigating its impact. We studied how the invasive glassy-winged sharpshooter (Homalodisca vitripennis Germar) can drive Pierce's disease outbreaks in vineyards, focusing on its potential to promote vine-to-vine (i.e., secondary) spread of Xylella fastidiosa relative to potential constraints stemming from seasonality in the pathosystem. First, we developed a general vector-borne disease model to understand the consequences for disease dynamics of (i) seasonal acquisition efficiency and (ii) seasonal host recovery from infection. Results of the modeling indicate that these two sources of seasonality could constrain disease incidence, particularly when working in concert. Next, we established a field cage experiment to determine whether H. vitripennis promotes vine-to-vine spread, and looked for evidence of seasonality in spread. Broadly, results from the experiment supported assumptions of the model; there was modest to significant increase in the frequency of pathogen spread over the first season, and those new infections that occurred later in the season were more likely to recover during winter. Ultimately, by the end of the second season, there was not evidence of significant secondary spread, likely due to a combination of seasonal constraints and low transmission efficiency by H. vitripennis. Collectively, these results suggest that, although H. vitripennis may be able to promote vine-to-vine spread in certain contexts, it may not be the key factor explaining its impact. Rather, the ability of H. vitripennis to drive epidemics is likely to be more directly related to its potential to reach higher population densities than native vectors.

Population model for the decline of Homalodisca vitripennis (Hemiptera: Cicadellidae) over a ten-year period

ABSTRACTThe glassy-winged sharpshooter, Homalodisca vitripennis (Germar), is an invasive pest which presents a major economic threat to grape industries in California, because it spreads a disease-causing bacterium, Xylella fastidiosa. In this note we develop a time and temperature dependent mathematical model to analyze aggregate population data for H. vitripennis from a 10-year study consisting of biweekly monitoring of H. vitripennis populations on unsprayed citrus, during which H. vitripennis decreased significantly. This model was fitted to the aggregate H. vitripennis time series data using iterative reweighted weighted least squares (IRWLS) with assumed probability distributions for certain parameter values. Results indicate that the H. vitripennis model fits the phenological and temperature data reasonably well, but the observed population decrease may possibly be attributed to factors other than the abiotic effect of temperature. A key factor responsible for this decline but not analyzed here could be biotic, for example, potentially parasitism of H. vitripennis eggs by Cosmocomoidea ashmeadi. A biological control program targeting H. vitripennis utilizing the mymarid egg parasitoid Cosmocomoidea (formerly Gonatocerus) ashmeadi (Girault) is described.

Evaluation of Flupyradifurone Against Glassy-Winged Sharpshooter on Ornamentals, 2018

Evaluation of Flupyradifurone Against Glassy-Winged Sharpshooter on Ornamentals, 2018

Evaluation of Glassy-Winged Sharpshooter Mortality Following Exposure to Aged Insecticide Residues, 2018

Evaluation of Glassy-Winged Sharpshooter Mortality Following Exposure to Aged Insecticide Residues, 2018

Pierce's Disease of Grapevines: A Review of Control Strategies and an Outline of an Epidemiological Model.

Xylella fastidiosa is a notorious plant pathogenic bacterium that represents a threat to crops worldwide. Its subspecies, Xylella fastidiosa subsp. fastidiosa is the causal agent of Pierce's disease of grapevines. Pierce's disease has presented a serious challenge for the grapevine industry in the United States and turned into an epidemic in Southern California due to the invasion of the insect vector Homalodisca vitripennis. In an attempt to minimize the effects of Xylella fastidiosa subsp. fastidiosa in vineyards, various studies have been developing and testing strategies to prevent the occurrence of Pierce's disease, i.e., prophylactic strategies. Research has also been undertaken to investigate therapeutic strategies to cure vines infected by Xylella fastidiosa subsp. fastidiosa. This report explicitly reviews all the strategies published to date and specifies their current status. Furthermore, an epidemiological model of Xylella fastidiosa subsp. fastidiosa is proposed and key parameters for the spread of Pierce's disease deciphered in a sensitivity analysis of all model parameters. Based on these results, it is concluded that future studies should prioritize therapeutic strategies, while investments should only be made in prophylactic strategies that have demonstrated promising results in vineyards.