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Our studies illustrate the dynamic nature of both the availability of split nuts and the prevalence of NOW after harvest, as well as illustrate the low density of moths needed to begin the next generation in the spring. Additionally, our work provides some insight into the relative importance of ground mummies compared to tree mummies. Although mortality was greater in ground mummies, they were more important because of their number.

”Large bug” damage to pistachio nuts varies by season, as well as among insect species and development stages, with larger bugs typically causing more damage than smaller bugs. We investigated pistachio damage by three large bug species (leaffooted bug, redshouldered stink bug and flat green stink bug) at different development stages and throughout the season, using field surveys and cage studies. Before fruit set occurs in June, most damaged nuts are dropped from the cluster without reducing fruit load. The midseason period (June to July) is the most critical because the damaged nuts remain in the cluster. After shell hardening, the kernel is largely protected from bug feeding.

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. The glassy-winged sharpshooter has been the subject of an area-wide suppression program in California for nearly two decades. Overreliance on a limited number of active ingredients including the neonicotinoid imidacloprid has resulted in increased levels of resistance to commonly applied products. In California, glassy-winged sharpshooters move between citrus, an important overwintering host, and vineyards. Accordingly, imidacloprid is routinely applied via the irrigation system in vineyards and citrus orchards. For soil applied applications, it may take days to weeks for concentrations in plants to increase to lethal doses. Further, as the dose of imidacloprid required to kill sharpshooters increases due to resistance, so too does the period that sharpshooters are exposed to sub-lethal doses. Response of glassy-winged sharpshooter to cowpea plants treated with sub-lethal doses of imidacloprid was evaluated by conducting no-choice and choice tests. In no-choice feeding assays, glassy-winged sharpshooters caged on plants treated with sub-lethal doses of imidacloprid ceased feeding and produced little excreta. Further, sub-lethal exposure to a range of doses over a 4-d period did not affect viability over a 9-wk post-exposure holding period on untreated plants. In choice-tests, glassy-winged sharpshooters avoided treated plants and were observed predominately on untreated plants. Results suggest that application of imidacloprid to vineyards and citrus orchards may push glassy-winged sharpshooters out of treated habitats rather than kill them. [ABSTRACT FROM AUTHOR]

Sharpshooters (Hemiptera: Cicadellidae: Cicadellinae) and spittlebugs (Hemiptera: Aphrophoridae: Aphrophorinae) have a worldwide distribution and are often associated with many crops. Because the geographic range of sharpshooters and spittlebugs often overlaps with the range of the plant pathogenic bacterium Xylella fastidiosa, the importance of these groups of insects in spreading X. fastidiosa rises to the level of a major socioeconomic problem. Managing diseases caused by X. fastidiosa is challenging for several reasons. First, multiple sequence types of the pathogen have been identified, with sequence type affecting host plant specificity. Second, multiple vector species may be present in an agroecosystem, and the host range of vector species is often broad. Although multiple vector control options such as biological, chemical, physical and cultural controls have been described, disease control programs must take into account biological and ecological parameters of locally dominant X. fastidiosa sequence types and vector species to develop suitable control strategies. Our review demonstrates how fundamental principles of vector reproductive biology, behaviour, nutrition and population and community ecology have influenced research on insect vectors and provides insights into priority research areas. [ABSTRACT FROM AUTHOR]

Pathogen spread by arthropod vectors is the outcome of pathogen–vector–plant interactions, as well as how these interactions are impacted by abiotic and biotic factors. While plant water stress impacts each component of the Pierce's disease pathosystem (Xylella fastidiosa Wells et al. insect vectors, and grapevines), the outcome of interactions in relation to pathogen spread is unknown. The objectives of this study were 1) to determine the role of plant water stress on vector acquisition and inoculation of X. fastidiosa under choice and no-choice conditions for source or recipient vines, and 2) to provide insights into the effects of vineyard irrigation regimes on spread of X. fastidiosa by using a host–vector epidemic model. Under no-choice conditions, pathogen acquisition increased as water stress increased in source plants, while inoculation was not affected by water status of recipient vines. Thus, under no-choice conditions, plant water stress increased transmission of X. fastidiosa. However, when vectors had a choice of an uninfected well-watered versus an infected water-stressed grapevine, transmission efficiency declined as water stress levels increased. While our experimental results produced wide uncertainty estimates, the epidemiological modeling suggested a non-linear relationship between water stress and pathogen spread: moderate water stress enhances pathogen spread but severe or no stress produce equivalent spread. In summary, both host plant condition and vector host preference interacted to determine transmission efficiency of X. fastidiosa. [ABSTRACT FROM AUTHOR]

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 glassywinged 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. To estimate energy reserves available to adult females at the beginning of feeding assays, residuals from a regression of wet weight on size were used. Analysis of a subset of females sacrificed at the beginning of feeding assays, demonstrated that females with a positive residual wet weight had higher lipid content and carried more eggs than females with a negative residual wet weight. To evaluate effects of diet and energy reserves on egg maturation, energy reserves available to females entering feeding assays on cowpea and grapevine were estimated. For females held on cowpea, residual wet weight and quantity of excreta produced over a 6-d feeding period affected egg production. In contrast, for females held on grapevine, only residual wet weight affected egg production. Comparison of cowpea and grapevine xylem sap determined that eight amino acids were more concentrated in xylem sap from cowpea than from grapevine. Collectively, the results suggest that glassy-winged sharpshooter population growth within crop monocultures will not depend solely on the nutritional quality of the specific crop for producing mature eggs but also on the quantity of energy reserves accumulated by females prior to entering that crop habitat. [ABSTRACT FROM AUTHOR]

A study on seasonal abundance of Auchenorrhyncha species and their infectivity by Xylella fastidiosa in the Apulia region of Italy was conducted to identify ideal periods for monitoring and adoption of potential control measures against insect vectors. Adult populations of Auchenorrhyncha species were monitored monthly over a 2-yr period from five olive groves. A total of 15 species were captured, identified, and tested for presence of X. fastidiosa by polymerase chain reaction (PCR). For three species, Philaenus spumarius L., Neophilaenus campestris (Fallèn), and Euscelis lineolatus Brullé, positive reactions to X. fastidiosa were obtained, on average, in 16.3, 15.9 and 18.4% of adult insects, respectively. Philaneous spumarius was the dominant species (39.8% of total Auchenorrhyncha captured) with the highest adult abundance in summer months. Adult P. spumarius and N. campestris were first detected between March and May in both years, and all insects tested during these periods (year 1: n=42, year 2: n=132) gave negative reactions to X. fastidiosa by PCR. Similarly, first adults of E. lineolatus that appeared from October to November (year 1: n=20, year 2: n=15) tested negative for presence of X. fastidiosa. Given the lack of transstadial and transovarial transmission of X. fastidiosa and considering that P. spumarius is univoltine, control measures against nymphal stages of P. spumarius should be investigated as means of population suppression to reduce spread of X. fastidiosa in olive groves. [ABSTRACT FROM AUTHOR]