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Abstract: BACKGROUND: Glassy‐winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) is an important vector of the bacterium Xylella fastidiosa, the causal agent of Pierce's disease of grapevine. Area‐wide insecticide applications have suppressed GWSS populations for ∼ 25 years, but reduced levels of insecticide susceptibility have been reported. Therefore, alternative methods of control are needed. Objectives of this study were to evaluate the efficacy of playback of vibrational mating communication signals for disrupting mating of GWSS in a natural vineyard setting and to evaluate spectral properties of signal transmission through vineyard trellis. RESULTS: Playback reduced mating of GWSS on grapevines. A total of 28 (of 134) male–female pairs mated in the control treatment (silence) and only one (of 134) pair mated when treated with the vibrational signal playback. Playback of vibrational signals through vineyard trellis was affected by distance from the signal source, with frequency composition being the highest at the source and lowest on vines positioned away from the source. Frequency composition in canes housing test insects decreased exponentially as distance from the source increased, whereas the relative amplitude of analyzed frequencies decreased linearly. CONCLUSION: Although further studies are needed prior to method implementation, data from this study continue to support integration of vibrational mating disruption with current methods to suppress GWSS populations. Published 2018. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

BACKGROUND The glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, is an important pest of grapevines due to its ability to transmit Xylella fastidiosa, the causal agent of Pierce's disease. GWSS mating communication is based on vibrational signals; therefore, vibrational mating disruption could be an alternative to insecticides for suppression of the GWSS population. Our objectives were to identify spectral features of the female signal that elicit male signaling, design disruptive signals able to alter male perception and acceptance of a female, and determine the signal intensity required for future field applications. RESULTS Male responses to playback of modified female signals were significantly reduced by 60-75% when part of the female signal spectral components above or below 400 Hz were deleted. Playback bioassays showed that transmission of an 80 Hz pure frequency tone to plants completely suppressed male signaling to female signal playback, even if the disruptive signal amplitude was 10 dB lower than the female signal playback. CONCLUSION Although the mechanism underlying cessation of male signaling activity in the presence of disruption is not yet understood, results suggest that an 80 Hz vibrational signal should be tested in laboratory and field experiments to assess its efficacy in disrupting mating of GWSS. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Animal communication is a complex behavior that is influenced by abiotic and biotic factors of the environment. Glassy-winged sharpshooters ( GWSS), Homalodisca vitripennis ( Germar) ( Hemiptera: Cicadellidae), primarily use vibrational signaling for courtship communication. Because GWSS is a major pest, transmitting the plant pathogenic bacterium Xylella fastidiosa Wells et al., interruption of communication is a possible avenue for control. Playback of white noise, pre-recorded female signals, and artificial female noise (continuously overlapping female signals) significantly reduced mating of GWSS when compared to silent control mating trials. Furthermore, to begin to determine the mechanism underlying playback control, female signaling activity was recorded in the presence of stimuli. In response to playback of female signals, females signaled (duet-like) more often than females tested in the absence of playback. After the first playback, almost two-thirds of females signaled a response within 3 s. Additionally, one-third of the females signaled within 1 s after cessation of white noise, and significantly more in the time periods following noise termination. Results highlight how GWSS responds to differing competitive disturbances in the environment and lays important ground work that possibly could be used to develop pesticide-free control methods. [ABSTRACT FROM AUTHOR]

We examined whether Gonatocerus ashmeadi Girault ( Hymenoptera: Mymaridae), a quasi-gregarious egg parasitoid of Homalodisca vitripennis ( Germar) ( Hemiptera: Cicadellidae), produces precise sex ratios under a field setting. Under laboratory conditions, previous studies have shown that G. ashmeadi exhibits strongly female-biased sex ratios with low variance in the number of males produced per host. Field-collected G. ashmeadi tend to produce much less female-biased sex ratios with high variance in male numbers. We found significant positive effects of proportion parasitism and host density on sex ratio. Proportion parasitism also had a positive effect on sex ratio variance. The findings of this study are discussed in the context of theoretical predictions. [ABSTRACT FROM AUTHOR]

The glassy-winged sharpshooter, Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), is an important insect vector of the xylem-limited plant pathogen Xylella fastidiosa Wells et al. that causes diseases in numerous plant species including food and feedstock crops, ornamentals and weeds. Both the pathogen and the vector are native to the Americas, and H. vitripennis has demonstrated high invasive ability but to date neither has been detected in Australia. The Australian wine grape, table grape, peach, plum, nectarine and citrus industries are particularly concerned about the arrival of X. fastidiosa and H. vitripennis because of the potential economic impact on these important commodities. Other commodity producers in Australia should also be concerned about this vector-pathogen, in particular the ornamental plant, avocado and olive industries. Past interceptions of H. vitripennis and the potential for X. fastidiosa to be moved in live plant material or within live vectors indicate the need for rapid detection of an incursion in areas considered at high risk. This requires identification of regions that have climatic and environmental conditions conducive to X. fastidiosa and H. vitripennis establishment as well as a detailed knowledge of their respective potential host plant ranges in new areas. These climatic regions and host plant species can then be targeted for monitoring in order to detect an incursion at an early stage. CLIMEX modelling has shown that much of coastal Australia has temperatures suitable for survival of both the vector and pathogen. A range of other requirements in addition to suitable climate must, however, be satisfied for an incursion to lead to establishment, proliferation and spread. This review article provides information that shows that the Australian environment is suitable for the establishment of H. vitripennis and that Australian native plant species are likely to serve as X. fastidiosa hosts and subsequent pathogen sources, and highlights future research directions. [ABSTRACT FROM AUTHOR]

BACKGROUND: The glassy winged sharpshooter, Homalodisca vitripennis, is an unusually robust and efficient leafhopper vector of Xylella fastidiosa. X. fastidiosa is the causative agent of Pierce's disease, almond scorch, citrus variegated chlorosis and other serious plant diseases. The present study was conducted to establish whether RNA interference (RNAi) was induced in nymphal H. vitripennis that were injected with actin dsRNAs and other dsRNAs. RESULTS: A dramatic reduction in target H. vitripennis actin mRNAs and the formation of small interfering RNAs (siRNAs), hallmarks of RNAi, were found following the injection of actin dsRNAs. Quantitative reverse transcription PCR indicated an 80% reduction in actin mRNA levels by 5 days post-injection. Western blot analysis showed a dramatic drop in actin protein levels by 3 days post-injection. Biological effects such as incomplete nymphal-adult ecdysis and > 95% mortality were also found following the injection of fifth-instar nymphs with actin dsRNA. Dramatic reductions in target mRNA levels were also found following the injection of other dsRNAs into fifth-instar H. vitripennis. CONCLUSION: The findings indicate that RNAi is induced in post-embryonic leafhoppers by dsRNA. The present system can be used to screen potential gene-silencing targets that can be used for reducing the vector competence of H. vitripennis and other leafhoppers. Copyright © 2011 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The xylem-limited bacterium Xylella fastidiosa Wells, Raju, Hung, Wiseberg, Mandelico-Paul & Brenner causes bacterial leaf scorch, a new disease of southern highbush blueberry [ Vaccinium corymbosum L. (Ericaceae) interspecific hybrids] in the southeastern USA. The bacterium is transmitted by sharpshooter leafhoppers (Hemiptera: Cicadellidae), with the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), being the most common potential vector in blueberry plantings. Considerable differences are observed in disease intensity among blueberry cultivars in the field, but it remains unknown whether these differences are due to variations in cultivar susceptibility to the bacterium, differences in attractiveness to its vector(s), or both. The settling and feeding behavior of GWSS was evaluated on three southern highbush blueberry cultivars (FL 86-19, Star, and Emerald) in the greenhouse; in previous field studies, these cultivars were found to be affected by bacterial leaf scorch at high, moderate, and low levels, respectively. Potted plants were caged together with field-collected GWSS adults for a period of 5 days, with either all three cultivars caged simultaneously (choice test) or individually (no-choice test). In the choice tests, no differences in cultivar attractiveness were observed during the first 2 days of study. However, from the 3rd day, significantly more adults settled on Emerald (52.7%) than on Star (25.5%) and FL 86-19 (17.7%). In contrast, in no-choice tests, the overall host plant acceptance for the three cultivars was similar, and 89.3-92.1% of adults settled on these plants. A significantly greater number of adults settled on the stems (79.3%) vs. the leaves (11.2%). Moreover, they preferred the middle portion of the shoot (56.9%) compared with the upper (7.8%) and the lower (14.7%) portions. In a separate study on FL 86-19, greater numbers of GWSS nymphs settled on the upper (actively growing) portion of the shoot (82.3%), whereas only 15.8 and 1.5% settled on the middle and lower portions, respectively. [ABSTRACT FROM AUTHOR]

The front cover image, by Rodrigo Krugner and Shira D. Gordon, is based on the Research Article Mating disruption of Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) by playback of vibrational signals in vineyard trellis, DOI: 10.1002/ps.4930. [ABSTRACT FROM AUTHOR]