Opportunities for optimizing fungal biological control agents for long-term and effective management of insect pests of orchards and vineyards: a review.

Novel tactics for controlling insect pests in perennial fruit and nut crops are needed because target pests often display decreased susceptibility to chemical controls due to overreliance on a handful of active ingredients and regulatory issues. As an alternative to chemical controls, entomopathogenic fungi could be utilized as biological control agents to manage insect pest populations. However, development of field ready products is hampered by a lack of basic knowledge.

Planococcus ficus (Hemiptera: Pseudococcidae) movement and demography: methods for generating cohorts for laboratory studies.

Planococcus ficus (Signoret) is a worldwide pest of grapevine. Mealybugs overwinter under bark and move into the grape canopy as the season progresses. Because crawlers are more active than later stages, mealybug movement behavior is likely to be stage specific.

High Growing Season Temperatures Limit Winter Recovery of Grapevines from Infection - Implications for Epidemiology in Hot Climates.

Management of widespread plant pathogens is challenging as climatic differences among crop-growing regions may alter key aspects of pathogen spread and disease severity. is a xylem-limited bacterial pathogen that is transmitted by xylem sap-feeding insects. Geographic distribution of is limited by winter climate, and vines infected with can recover from infection when held at cold temperatures.

Glassy-Winged Sharpshooters Cease Feeding and Avoid Plants Treated With Sub-Lethal Doses of the Neonicotinoid Insecticide Imidacloprid.

Insecticides are a primary means for suppressing populations of insects that transmit plant pathogens. Application of insecticides for limiting the spread of insect-transmitted plant pathogens is often most effective when applied on an area-wide scale. The glassy-winged sharpshooter is a vector of the bacterial pathogen Xylella fastidiosa, which causes numerous plant diseases including Pierce's disease of grapevine.

Evaluation of Alfalfa Fields and Pastures as Sources of Spissistilus festinus (Hemiptera: Membracidae): Quantification of Reproductive and Nutritional Parameters.

The threecornered alfalfa hopper (Spissistilus festinus) is a pest of grapevine, with damage caused by transmission of grapevine red blotch virus. Because grapevine is not a preferred host of the threecornered alfalfa hopper, abundance in vineyards depends on proximity to source habitats and presence of preferred hosts in vineyard understories. The potential for alfalfa fields and pastures in the Central Valley of California to serve as sources of threecornered alfalfa hopper was evaluated by quantifying parameters associated with threecornered alfalfa hopper reproductive and nutritional status.

Mitigating an Epidemic of Resistance with Integrated Disease Management Tactics: Conflicting Management Recommendations from Insecticide Resistance and Epidemiological Models.

Insect-transmitted plant pathogens threaten crop production worldwide. Because a single feeding bout may be sufficient for a vector to transmit a pathogen that kills the plant, treatment thresholds for vectors of plant pathogens are low. For many vector species, overreliance on chemical controls has resulted in evolution of insecticide resistance.

Nutritional and Physiological Regulation of Glassy-Winged Sharpshooter Oogenesis.

The glassy-winged sharpshooter (Homalodisca vitripennis (Germar); Hemiptera: Cicadellidae: Cicadellinae) is an invasive insect that transmits the plant pathogenic bacterium Xylella fastidiosa Wells et al. (Xanthomonadales: Xanthomonadacae). While adult glassy-winged sharpshooter must feed to produce eggs, the role of nutritional status on initiating oogenesis is poorly understood.

Spissistilus festinus (Hemiptera: Membracidae) susceptibility to six generalist predators.

Spissistilus festinus (Say) (Hemiptera: Membracidae) was shown to transmit Grapevine red blotch virus (GRBV) in a greenhouse study. Grapevines infected with GRBV exhibit reduced sugar accumulation, altered secondary metabolite production and delayed berry maturation that negatively impacts wine quality and economics. Augmentative biocontrol may be a useful integrated pest management (IPM) tool for suppressing S.

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

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, . During the growing season, rates of spread in vineyards are affected by changes in pathogen distribution within chronically infected grapevines and by vector population dynamics.

Spread of Citrus Tristeza Virus in Citrus Orchards in Central California.

In California, citrus tristeza virus (CTV) is regulated by a State Interior Quarantine. In CTV abatement districts in central California, trees with CTV that react to MCA13 (MCA13-positive [MCA13+]), a strain-discriminating monoclonal antibody, are rogued to prevent virus spread. The Tulare County Pest Control District, however, does not participate in this abatement program except for a 1.

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

Bacterial leaf scorch disease caused by occurs in southern highbush blueberry varieties in the southeastern United States. Susceptibility to varies by blueberry cultivar, and these interactions are often strain-specific. subsp.

Effects of Nymphal Diet and Adult Feeding on Allocation of Resources to Glassy-Winged Sharpshooter Egg Production.

The glassy-winged sharpshooter is an invasive insect capable of transmitting the bacterial pathogen Xylella fastidiosa. Pre-oviposition periods of laboratory-reared glassy-winged sharpshooters are variable. Here, two questions were addressed: does nymphal diet affect pre-oviposition period and how do allocation patterns of resources differ for females that produce eggs versus females that do not? Nymphs were reared on one of three host plant species: cowpea, sunflower, or sorghum.

Alfalfa and Pastures: Sources of Pests or Generalist Natural Enemies?

Pierce's disease of grapevine and almond leaf scorch disease are both caused by the bacterial pathogen Xylella fastidiosa Wells et al. In the Central Valley of California, Draeculacephala minerva Ball (Hemiptera: Cicadellidae) is the most common vector of X. fastidiosa.

Effects of Energy Reserves and Diet on Glassy-Winged Sharpshooter Egg Maturation.

The glassy-winged sharpshooter is an invasive insect capable of transmitting the plant pathogen Xylella fastidiosa. As rates of pathogen spread are a function of vector abundance, identification of factors contributing to glassy-winged sharpshooter egg production will aid in predicting population growth. Here, effects of stored energy reserves and adult diet on glassy-winged sharpshooter egg maturation were evaluated.

Effects of Xylem-Sap Composition on Glassy-Winged Sharpshooter (Hemiptera: Cicadellidae) Egg Maturation on High- and Low-Quality Host Plants.

Glassy-winged sharpshooters must feed as adults to produce mature eggs. Cowpea and sunflower are both readily accepted by the glassy-winged sharpshooter for feeding, but egg production on sunflower was reported to be lower than egg production on cowpea. To better understand the role of adult diet in egg production, effects of xylem-sap chemistry on glassy-winged sharpshooter egg maturation was compared for females confined to cowpea and sunflower.

Sequence polymorphism in an insect RNA virus field population: A snapshot from a single point in space and time reveals stochastic differences among and within individual hosts.

Population structure of Homalodisca coagulata Virus-1 (HoCV-1) among and within field-collected insects sampled from a single point in space and time was examined. Polymorphism in complete consensus sequences among single-insect isolates was dominated by synonymous substitutions. The mutant spectrum of the C2 helicase region within each single-insect isolate was unique and dominated by nonsynonymous singletons.

Disentangling Effects of Vector Birth Rate, Mortality Rate, and Abundance on Spread of Plant Pathogens.

Models on the spread of insect-transmitted plant pathogens often fix vector population size by assuming that deaths are offset by births. Although such mathematical simplifications are often justified, deemphasizing parameters that govern vector population size is problematic, as reproductive biology and mortality schedules of vectors of plant pathogens receive little empirical attention. Here, the importance of explicitly including parameters for vector birth and death rates was evaluated by comparing results from models with fixed vector population size with models with logistic vector population growth.

Effects of Glassy-Winged Sharpshooter (Hemiptera: Cicadellidae) Feeding, Size, and Lipid Content on Egg Maturation.

The glassy-winged sharpshooter (Homalodisca vitripennis) is synovigenic and must feed as an adult to produce eggs. Egg maturation rates depend on the host plant species provided to the adult female for feeding and are variable for females provided with the same host plant species. Here, the contribution of female size and lipid content to variation in egg maturation rates among females held on the same host plant species was assessed.

Evaluation of Olive as a Host of Xylella fastidiosa and Associated Sharpshooter Vectors.

Olive (Olea europaea) trees exhibiting leaf scorch or branch dieback symptoms in California were surveyed for the xylem-limited, fastidious bacterium Xylella fastidiosa. Only approximately 17% of diseased trees tested positive for X. fastidiosa by polymerase chain reaction, and disease symptoms could not be attributed to X.

Evaluation of a method to quantify glassy-winged sharpshooter (Hemiptera: Cicadellidae) egg maturation during a feeding assay.

A method to improve an assay relating adult feeding to egg maturation by the glassy-winged sharpshooter (Hemiptera: Cicadellidae) was evaluated. The assay consisted on confining females to cowpea stems and quantifying feeding and egg maturation. Feeding was quantified by measuring excreta production.

Distinguishing Nonpareil marketing group almond cultivars through multivariate analyses.

More than 80% of the world's almonds are grown in California with several dozen almond cultivars available commercially. To facilitate promotion and sale, almond cultivars are categorized into marketing groups based on kernel shape and appearance. Several marketing groups are recognized, with the Nonpareil Marketing Group (NMG) demanding the highest prices.

Quantifying host potentials: indexing postharvest fresh fruits for spotted wing Drosophila, Drosophila suzukii.

Novel methodology is presented for indexing the relative potential of hosts to function as resources. A Host Potential Index (HPI) was developed as a practical framework to express relative host potential based on combining results from one or more independent studies, such as those examining host selection, utilization, and physiological development of the organism resourcing the host. Several aspects of the HPI are addressed including: 1) model derivation; 2) influence of experimental design on establishing host rankings for a study type (no choice, two-choice, and multiple-choice); and, 3) variable selection and weighting associated with combining multiple studies.

Plant water stress effects on the net dispersal rate of the insect vector Homalodisca vitripennis (Hemiptera: Cicadellidae) and movement of its egg parasitoid, Gonatocerus ashmeadi (Hymenoptera: Mymaridae).

Homalodisca vitripennis (Germar), a vector of Xylella fastidiosa, is associated with citrus plantings in California. Infested citrus orchards act as a source of vectors to adjacent vineyards where X. fastidiosa causes Pierce's disease.

Roguing with replacement in perennial crops: conditions for successful disease management.

Replacement of diseased plants with healthy plants is commonly used to manage spread of plant pathogens in perennial cropping systems. This strategy has two potential benefits. First, removing infected plants may slow pathogen spread by eliminating inoculum sources.

Effects of entomopathogenic nematodes on evolution of pink bollworm resistance to Bacillus thuringiensis toxin Cry1Ac.

The evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from Bacillus thuringiensis (Bt). However, fitness costs may act to delay pest resistance to Bt toxins. Meta-analysis of results from four previous studies revealed that the entomopathogenic nematode Steinernema riobrave (Rhabditida: Steinernematidae) imposed a 20% fitness cost for larvae of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), that were homozygous for resistance to Bt toxin Cry1Ac, but no significant fitness cost was detected for heterozygotes.