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To elucidate phylogenetic relationships within the leafhopper's subfamily Megophthalminae (Hemiptera: Cicadellidae), mitogenomes of 12 species of the subfamily were sequenced and assembled. These were added to the mitogenomes of the eight other species that are currently available. Mitogenome size ranged from 15,193 bp in Onukigallia onukii (Matsumura, 1912) to 15,986 bp in Multinervis guangxiensis (Li and Li, 2013), they all contained 37 genes, and gene order was similar to that in other leafhoppers. Nucleotide composition analysis showed that the AT content was higher than that of GC, and the protein-coding genes usually ended with A/T at the 3rd codon position. The K a/ K s ratio showed that the CYTB gene has the slowest evolutionary rate, while ND4 is the gene with the fastest evolutionary rate. Relative synonymous codon usage analysis revealed the most frequently used codon was UUA (L), followed by CGA (R), and the least frequently used codon was CCG (P). Parity plot and neutrality plot analyses showed that the codon usage bias of mitochondrial genes was influenced by natural selection and mutation pressure. However, natural selection plays a major role, while the effect of mutation pressure was small. Effective number of codons values were 40.15–49.17, which represented relatively low codon bias. Phylogenetic analyses based on three datasets (AA, 13PCG, 13PCG_2rRNA) using two methods (maximum likelihood and Bayesian inference). In the obtained topology, the Megophthalminae species were clustered into a monophyletic group. In conclusion, our results clarify structural modules of the mitochondrial genes and confirm the monophyly of Megophthalminae within Cicadellidae. [ABSTRACT FROM AUTHOR]

Cicadellidae (leafhoppers) may be the most diverse and abundant insect herbivores in terrestrial ecosystems worldwide, with more than 23,000 described species in 20 extant subfamilies. Although prior studies have supported the monophyly of most recognized subfamilies, relationships among these groups remain inconsistently resolved and previous molecular phylogenies have failed to support the monophyly of a few subfamilies. To help address this deficiency, we combined 24 new complete mitogenomes representing 6 previously unsequenced subfamilies and 13 tribes with previously available data to create a dataset of 79 cicadellid taxa representing 16 subfamilies for phylogenetic analysis. The new analyses confirm that leafhopper mitochondrial genomes are highly conservative in overall structure, with only a few rare rearrangements of tRNAs. All phylogenetic analyses consistently supported the monophyly of previously recognized cicadellid tribes for which more than 1 representative was included and all of the included subfamilies were also consistently recovered as monophyletic with the exception of Aphrodinae and Eurymelinae. Bayesian inference and Maximum Likelihood analyses with site-homogeneous models are only slightly affected by nucleotide compositional heterogeneity and yield more stable phylogenetic relationships of family-group taxa than analyses with a heterogeneous-site mixture model using PhyloBayes. Molecular divergence time estimates indicate that the main lineages of Cicadellidae, most corresponding to recognized subfamilies, diverged during the Cretaceous period (93–121 Mya). [ABSTRACT FROM AUTHOR]

Aster leafhopper (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) is a polyphagous insect species that migrates into the upper Midwest of the United States and the Western Canadian Prairies. Populations of this insect are associated with the transmission of a plant pathogen (Candidatus Phytoplasma asteris, 16SrI) to several annual crops and perennial plant species. Previous studies suggest that aster leafhoppers can sometimes prefer less suitable hosts for their development and survival, yet it is unclear if this lower performance on certain plant species is associated with reduced or impaired probing behaviors due to characteristics of the plants. To characterize the probing behaviors of aster leafhoppers, direct current electropenetrography recordings of male and female adults on barley (Polaes: Poaceae: Hordeum vulgare L.) were combined with plant histology, allowing the identification of nine waveforms and their proposed biological meanings. For each waveform, the number of waveform events per insect (NWEI), the waveform duration per insect (WDI), the waveform duration per event per insect (WDEI), and the percentage of recording time were calculated and statistically compared between sexes. Male and female aster leafhoppers exhibited similar behavioral responses for most of these variables, except for the NWEI for waveforms associated with nonprobing activities and the pathway phase. In these cases, male aster leafhoppers exhibited a higher number of events than females. Comparison of the proposed waveforms in this study with previous work on other hemipteran species provided additional support to the interpretation of the biological activities associated with each waveform. [ABSTRACT FROM AUTHOR]

The US cherry and stone fruit industries have periodically experienced devastating outbreaks of X-disease phytoplasma (XDP) since the 1930s, with an ongoing epidemic occurring since 2010. This disease is critically impacting Prunus spp. and the stone fruit industry, causing underdeveloped, bitter, and misshapen fruit on economically important crops, primarily cherries, peaches, and nectarines, making the fruit unmarketable. Trees cannot recover from this disease and eventually die if they are not removed. It takes at least 1 yr for symptoms to appear, postinfection, which hinders disease management efforts. The phytoplasma, Candidatus Phytoplasma pruni, is a phloem-limited intracellular bacterium that is spread by grafting and leafhopper (Hemiptera: Cicadellidae) feeding. Several leafhopper species are known to transmit XDP, of which Colladonus spp. are considered the most important vectors in the Western United States and are native to this region. Colladonus spp. feed and oviposit on a wide variety of broadleaf perennial plants, including mallow, alfalfa, and clover. These plants are also hosts of the phytoplasma. In Western United States, these leafhoppers have 3 periods of adult activity: May–June, late July–August, and October. The highest rates of pathogen transmission likely occur during the last 2 activity periods due to the high abundance of leafhoppers and a postharvest increase of XDP titers in trees. Using known activity periods and host plants of the leafhoppers, growers can monitor and strategically manage the vectors, which, when combined with the removal of infected trees and ground-cover hosts, should help limit the spread of X-disease. [ABSTRACT FROM AUTHOR]

Polyphagous insects are characterized by a broad diet comprising plant species from different taxonomic groups. Within these insects, migratory species are of particular interest, given that they encounter unpredictable environments, with abrupt spatial and temporal changes in plant availability and density. Aster leafhoppers (Hemiptera: Cicadellidae: Macrosteles quadrilineatus Forbes) arrive in the Canadian Prairies in spring and early summer and are the main vector of a prokaryotic plant pathogen known as Aster Yellows Phytoplasma (AYp) (Candidatus Phytoplasma asteris). Host choice selection behavior of Aster leafhoppers was evaluated through two-choice bioassays, using domesticated and wild plants species commonly found in the Canadian Prairies. Leaf tissues from these plants were collected and stained to quantify the number of stylet sheaths and eggs. To assess possible effects due to insect infection, two-choice bioassays were repeated using leafhoppers infected with AYp and a subset of plant species. When two domesticated or wild plant species were presented together, similar numbers of uninfected Aster leafhoppers were observed on both plant species in most combinations. In domesticated–wild plant bioassays, uninfected Aster leafhoppers preferred to settle on the domesticated species. There was little to no association between settling preferences and stylet sheath and egg counts. These findings provide a better understanding of AY epidemiology and suggest that after domesticated species germination, leafhoppers could move from nearby wild plants into the preferred cereals (Poales: Poaceae) to settle on them, influencing the risk of AYp infection in some of these species. [ABSTRACT FROM AUTHOR]

Homalodisca vitripennis (Hemiptera: Cicadellidae), known as the glassy-winged sharpshooter, is a xylem feeding leafhopper and an important agricultural pest as a vector of Xylella fastidiosa, which causes Pierce's disease in grapes and a variety of other scorch diseases. The current H. vitripennis reference genome from the Baylor College of Medicine's i5k pilot project is a 1.4-Gb assembly with 110,000 scaffolds, which still has significant gaps making identification of genes difficult. To improve on this effort, we used a combination of Oxford Nanopore long-read sequencing technology combined with Illumina sequencing reads to generate a better assembly and first-pass annotation of the whole genome sequence of a wild-caught Californian (Tulare County) individual of H. vitripennis. The improved reference genome assembly for H. vitripennis is 1.93-Gb in length (21,254 scaffolds, N50¼650Mb, BUSCO completeness ¼ 94.3%), with 33.06% of the genome masked as repetitive. In total, 108,762 gene models were predicted including 98,296 protein-coding genes and 10,466 tRNA genes. As an additional community resource, we identified 27 orthologous candidate genes of interest for future experimental work including phenotypic marker genes like white. Furthermore, as part of the assembly process, we generated four endosymbiont metagenome-assembled genomes, including a high-quality near complete 1.7-Mb Wolbachia sp. genome (1 scaffold, CheckM completeness = 99.4%). The improved genome assembly and annotation for H. vitripennis, curated set of candidate genes, and endosymbiont MAGs will be invaluable resources for future research of H. vitripennis. [ABSTRACT FROM AUTHOR]

Agroecosystems undergo frequent anthropogenic disturbance that may affect the diversity, community, and abundance of natural enemies living there. In the tropics, annual crops such as maize are planted two times (year-round crops) or one time (seasonal crops) per year. Little is known about how natural enemies of insect pests respond to maize agroecosystems planted one vs. two times during each annual cycle. The objective was to investigate the diversity and parasitism of egg parasitoids of the pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) in maize agroecosystems planted year-round and seasonally. Potted maize plants with D. maidis eggs were placed within these two maize agroecosystems to attract egg parasitoids during the maize-growing wet season in Mexico. In these two maize agroecosystems, similar levels of diversity were found, using the Shannon-Wiener index (H ′). Communities of parasitic wasps were found attacking the eggs of D. maidis in both maize agroecosystems, but there were differences in the composition of these communities. In the year-round maize agroecosystem, Paracentrobia sp. near subflava (Girault) (Hymenoptera: Trichogrammatidae) was the most common, while Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) was most common in the seasonal maize. A greater total abundance and total rate of parasitoid emergence were found in the year-round maize agroecosystem compared with the seasonal maize. In addition, a positive relationship between the number of D. maidis eggs and parasitoid abundance was found in both maize agroecosystems. However, a negative density dependence between the number of D. maidis eggs and the percentage of parasitism was found in both maize agroecosystems. [ABSTRACT FROM AUTHOR]

Erythroneura sudra is a leafhopper occurring in northern China, which causes significant damage to fruit. The relationships between E. sudra and five fruit tree species (Rosaceae) were studied for 3 yr. The highest relative density of E. sudra was recorded on leaves of Amygdalus persica L. and Cerasus pseudocerasus Lindl. Likewise, it had the highest survival rate and shortest developmental time when it fed on these two plants species, indicating that they were the most preferred by E. sudra than the other plant species. The relative density and growth performance of E. sudra were negatively correlated with the levels of tannins and flavonoids in the leaves of the host species. Both plant species had relatively lower flavonoids and tannins, and this may have contributed to the enhanced survival and population growth of E. sudra. These results can guide the development of improved management strategies for this pest. [ABSTRACT FROM AUTHOR]

Aims: In this study, binding between the immunodominant membrane protein Imp of the 16SrV‐D phytoplasma associated with Flavescence dorée disease (FD‐Dp) and insect proteins of vectors and non‐vectors of FD‐Dp was tested. Methods and Results: Six Auchenorrhyncha species, from distantly related groups were selected: Scaphoideus titanus, Euscelidius variegatus, Macrosteles quadripunctulatus, Zyginidia pullula (Cicadomorpha), Ricania speculum and Metcalfa pruinosa (Fulgoromorpha). The vector status of each species was retrieved from the literature or determined by transmission trials in this study. A His‐tagged partial Imp protein and a rabbit polyclonal antibody were synthesized and used for Western and Far‐Western dot Blot (FWdB) experiments. Total native and membrane proteins (MP) were extracted from entire bodies and organs (gut and salivary glands) of each insect species. FWdB showed decreasing interaction intensities of Imp fusion protein with total proteins from entire bodies of S. titanus, E. variegatus (competent vectors) and M. quadripunctulatus (non‐vector), while no interaction signal was detected with the other three species (non‐vectors). A strong signal detected upon interaction of FD‐D Imp and MP from guts of closely related insects supports the role of this organ as the first barrier to ensure successful transmission. Conclusions: Our results showed that specific Imp binding, correlated with vector status, is involved in interactions between FD‐Dp and insect proteins. Significance and Impact of the Study: Integrating knowledge on host–pathogen protein–protein interactions and on insect phylogeny would help to identify the actual range of vectors of phytoplasma strains of economic importance. [ABSTRACT FROM AUTHOR]

Orientus ishidae (Matsumura) (subfamily Deltocephalinae) is an Asian species now widespread in Europe, and a vector of 16SrV phytoplasmas agents of grapevine Flavescence dorée (FDP). Embryonic and post-embryonic development, spatial distribution, and relationships with grapevine of nymphs were studied under field and laboratory conditions. Egg-hatching dynamics and post-embryonic development of nymphs were studied by collecting grapevine wood from managed and unmanaged vineyards (including bot European Vitis vinifera L. and wild American rootstocks) and storing it inside rearing cages at T = 21–23°C. Field sampling of nymphs were made on both grapevine and two elective host plants of O. ishidae: hazelnut and hornbeam. Taylor's Power Law was applied to assess the aggregation coefficient of early- (first and second) and late- (third to fifth) life instars on leaves and shoots of host plants. More nymphs were obtained from wood collected in unmanaged rather than managed vineyards. Under lab conditions, the embryonic development lasted 34–48 d, whereas the whole post-embryonic development averaged 27 d. Under field conditions, early instars peaked at the end of May, and late instars peaked 2–4 wk later. The aggregation patterns decreased from early to late instars, and from leaves to shoots. Very few nymphs were observed on unmanaged grapevine, either European or American, and none on managed European grapevine. Some behavioral and FDP epidemiological consequences of the results obtained are discussed. [ABSTRACT FROM AUTHOR]

Because of concerns over recent declines in overall biodiversity in suburban areas, homeowners are attempting to improve the ecological functioning of their landscapes by incorporating native plants. Native plants are important for supporting native herbivorous insects, but it is unknown whether the native plants that are commercially available, typically cultivated varieties (cultivars) of a single genotype, are equally effective as food sources as the local, wild-type plants. We compared the hemipteran communities feeding on cultivars and wild-propagated plants for four species of native perennials commonly used as ornamentals. Of 65 hemipteran species collected, 35 exhibited a preference for some plant species over others, indicating a high degree of host-plant specialization. Moreover, the insect community associated with cultivars was distinct from the insect community associated with wild-type plants for each plant species, with three to four insect species accounting for most of the observed difference. Total insect abundance and insect biomass differed between cultivars and wild-propagated plants, but the direction of the difference changed over time and was not consistent among plant species. Species richness and a diversity index (the Q statistic) did not differ between cultivars and wild-type plants. These data suggest that abundance and diversity of hemipteran insects does not depend on the source of the plant material per se, but rather on the particular characteristics of cultivars that distinguish them from the wild type. [ABSTRACT FROM AUTHOR]

Due to their nutritional value and function as soil nitrogen fixers, production of pulses has been increasing markedly in the United States, notably in the dryland areas of the Northern Plains and the Pacific Northwest United States (NP&PNW). There are several insect-transmitted viruses that are prevalent and periodically injurious to pulse crops in the NP&PNW and elsewhere in North America. Others are currently of minor concern, occurring over limited areas or sporadically. Others are serious constraints for pulses elsewhere in the world and are not currently known in North America, but have the potential to be introduced with significant economic consequences. Managing plant viruses and the diseases they cause requires effective diagnostics, knowledge of virus vectors, virus transmission biology and ecology. A comprehensive compendium to inform producers and researchers about viruses currently and potentially affecting pulses in North America is needed. Here we provide an overview of insect transmitted viruses and their biology, followed by descriptions of the structure, infection biology, host ranges, symptoms, interspecific interactions, and current management options including host plant resistance and vector control for 33 viruses affecting or potentially affecting pulses in the United States and Canada. These are organized based on their transmission biology into persistently transmitted (families Geminiviridae , Luteoviridae and Nanoviridae), semi-persistantly transmitted (Secoviridae), and nonpersistantly transmitted (Betaflexiviridae , Bromoviridae and Potyviridae) viruses. We conclude with an overview of the principles of managing insect-transmitted viruses and an outline of areas requiring further research to improve management of viruses in pulses currently and into the future. [ABSTRACT FROM AUTHOR]

During 2015, the influence of kaolin applications and bunch-zone leaf removal on the grapevine leafhoppers, Empoasca vitis (Gö the) and Zygina rhamni Ferrari, and their egg parasitoids (Anagrus spp.) was tested in four vineyards of northeastern Italy. The mode of action of kaolin on E. vitis nymphs was also investigated in the laboratory. In the treated plots, kaolin was applied at a rate of 2% w/v on two occasions separated by 5-6 d. In two vineyards, it was applied either on the whole canopy or the bunch zone at the beginning of the E. vitis second generation (preventive criterion), and in the other two vineyards, it was applied to the whole canopy at the peak of the E. vitis third generation (curative criterion). Both the preventive and curative kaolin applications caused a significant decrease in the populations of E. vitis and Z. rhamni nymphs. The effect of the preventive applications was persistent and was associated with reduced E. vitis leaf symptoms. Kaolin did not influence the activity of Anagrus spp. Bunch-zone leaf removal did not affect leafhopper populations. Laboratory experiments showed that inhibition of feeding was the main mode of action through which kaolin affected nymph populations. Based on these outcomes, kaolin could be a valuable alternative to synthetic insecticides in controlling grapevine leafhoppers. [ABSTRACT FROM AUTHOR]

The leafhopper Matsumuratettix hiroglyphicus (Matsumura) (Hemiptera: Cicadellidae) is an important vector of phytoplasma causing white leaf disease in sugarcane. Thus, the aim of our study was to understand and describe the stylet-probing activities of this vector while feeding on sugarcane plants, by using direct current (DC) electrical penetration graph (EPG) monitoring. The EPG signals were classified into six distinct waveforms, according to amplitude, frequency, voltage level, and electrical origin of the observed traces during stylet penetration into the host plant tissues (probing). These six EPG waveforms of probing behavior comprise no stylet penetration (NP); stylet pathway through epidermis, mesophyll, and parenchymal cells (waveform A); contact at the bundle sheath layer (waveform B); salivation into phloem sieve elements (waveform C); phloem sap ingestion (waveform D); and short ingestion time of xylemsap (waveform E). The above waveformpatterns were correlated with histological data of salivary sheath termini in plant tissue generated from insect stylet tips. The key findings of this study were that M. hiroglyphicus ingests the phloem sap at a relatively higher rate and for longer duration from any other cell type, suggesting that M. hiroglyphicus is mainly a phloem-feeder. Quantitative comparison of probing behavior revealed that females typically probe more frequently and longer in the phloem than males. Thus, females may acquire and inoculate greater amounts of phytoplasma than males, enhancing the efficiency of phytoplasma transmission and potentially exacerbating disease spreading. Overall, our study provides basic information on the probing behavior and transmissionmechanism of M. hiroglyphicus. [ABSTRACT FROM AUTHOR]

Integrative taxonomy is considered a reliable taxonomic approach of closely related and cryptic species by integrating different sources of taxonomic data (genetic, ecological, and morphological characters). In order to infer the boundaries of seven species of the evacanthine leafhopper genus B undera Distant, 1908 ( Hemiptera: Cicadellidae), an integrated analysis based on morphology, mitochondrial DNA, and hyperspectral reflectance profiling (37 spectral bands from 411-870 nm) was conducted. Despite their morphological similarities, the genetic distances of the cytochrome c oxidase subunit I ( COI) gene among the tested species are relatively large (5.8-17.3%). The species-specific divergence of five morphologically similar species ( B undera pellucida and B undera spp. 1-4) was revealed in mitochondrial DNA data and reflectance profiling. A key to identifying males is provided, and their morphological characters are described. Average reflectance profiles from the dorsal side of specimens were classified based on linear discriminant analysis. Cross-validation of reflectance-based classification revealed that the seven species could be distinguished with 91.3% classification accuracy. This study verified the feasibility of using hyperspectral imaging data in insect classification, and our work provides a good example of using integrative taxonomy in studies of closely related and cryptic species. © 2015 The Linnean Society of London [ABSTRACT FROM AUTHOR]

Anagrus erythroneurae S. Trjapitzin & Chiappini and Anagrus daanei Triapitsyn are the key parasitoids of the western grape leafhopper (Erythroneura elegantula Osborn) in northern California vineyards. Erythroneura elegantula overwinters as an adult in reproductive diapause. To successfully overwinter, Anagrus spp. must locate an alternate leafhopper host that overwinters in an egg stage that they can parasitize. These alternate leafhopper hosts are thought to be primarily located in the natural habitats surrounding vineyards. This study identifies the noncrop host plants utilized by Anagrus spp. not only during the overwintering period but throughout the entire year, as well as the leafhopper species associated with these host plants. Over a 2-yr period, Anagrus spp. and leafhoppers were sampled from numerous plants in natural and cultivated habitats surrounding vineyards. Results from this study confirm previously known Anagrus spp. host plants, but also identify new host plant species. Some of the host plants harbored Anagrus spp. year-round while others were utilized only during certain periods of the year. Leafhoppers associated with Anagrus spp. host plants may potentially serve as the alternate host utilized by Anagrus spp. on these plants, but this was not confirmed in the current study. Records of E. elegantula demonstrate their cyclical movement between the vineyard floor (winter), temporary noncrop hosts (spring/fall), and the grape vine canopy (summer). [ABSTRACT FROM AUTHOR]

Tea green leafhoppers (Empoasca spp.) are considered one of the major pests in tea plantations in Asia. They are, however, difficult to monitor due to their size and flying and jumping abilities. In this study, we clarified the identification of the leafhopper species encountered in our study plantations and examined the impacts of sampling methods in estimating population abundance and sex ratio. The natural sex ratio of eggs, nymphs, and adults of tea green leafhopper and the differences between male and female were tested. Despite previous reports that Empoasca vitis (Goethe) was the major leafhopper present in our study area, our results showed that only Empoasca onukii Matsuda was found. Variation in population size over time and bias in sex ratio depending on the sampling methods were found in our monitoring experiments. In general, adult males were more attracted to yellow sticky cards than females. We believe that because female leafhoppers should be the target in pest control, yellow sticky cards may not be the most suitable monitoring or effective control of tea green leafhopper We demonstrate the importance of understanding the implications of sampling techniques for population estimation and sex ratio bias as well as how temporal variation may affect monitoring results. Precise monitoring should take into consideration the different life histories of male and female. [ABSTRACT FROM AUTHOR]

The Old World leafhopper genus Futasujinus Ishihara is revised and redescribed. Eight species, including three new species, are recognized in the genus: F. amuriensis (Metcalf) (China, Japan, Korea, Mongolia, and Russia), F. biarmatw Dlabola (Mongolia), F. candidas (Matsumura) (China, Russia, Korea, and Japan), F. dietrichi sp. nov. (China), F. hastatus sp. nov. (China), F. koreacola Kwon & Lee, 1979 (Korea), F. towadensis (Matsumura) (Japan), and F. truncates sp. nov. (China). All species from China are described. A key to the species in this genus is given, and their genital structures are illustrated. [ABSTRACT FROM AUTHOR]

Dalbidus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae) is the most important leafhopper vector of maize plant pathogens in the Americas. However, until now, no study has investigated the overwintering biology of its egg parasitoids. The objective in this study was to find egg parasitoids of D. maidis in perennial grass, volunteer maize, stubble, and drip-irrigated maize habitats in the winter season. Two-week-old D. maidis females were allowed to oviposit on young maize plants for 72 h under laboratory conditions. The oviposited healthy D. maidis eggs (sentinel eggs) on the young maize plants were exposed to natural parasitism maintained on perennial grasses, volunteer maize, and stubble 2 mo after the onset of winter, and on perennial grasses, volunteer maize, and drip-irrigated maize at the end of winter. The abundance of D. maidis adults in these habitats was also determined. Two months after the start of winter, D. maidis eggs were parasitized by the wasp Oligosita sp. from perennial grasses and volunteer maize, whereas at the end of winter, the eggs were parasitized by the wasps Oligosita sp. and Anagrus columbi Perkins from perennial grasses, volunteer maize, and drip-irrigated maize. Overall, more adult parasitoids of D. maidis eggs were found on perennial grasses. Adult corn leafhoppers were absent from perennial grasses at the end of winter; however, other Deltocephalinae leafhopper species were present, suggesting that egg parasitoids of D. maidis use another leafhopper host during winter. Furthermore, adults of five Deltocephalinae species were parasitized by dryinids and strepsipterans throughout the 2012-2013 winter in perennial grasses. [ABSTRACT FROM AUTHOR]

In Chile, phytoplasmas have been reported in sugar beet, grapevine, peony, and Chilean shrubs. 'Candidatus Phytoplasma ulmi' have been detected in plants of Ugni molinaeTurczaninow (Myrta-ceae) and the leafhopper Amplicephalus curtulus Linnavuori & DeLong. We evaluated the possibility of phytoplasma transmission from native plants to grasses by A. curtulus and the possible effect on the plant hosts. Newly emerged adults were placed in cages with phytoplasma-infected U. molinae for 72 h (acquisition access period). These plants were then replaced by healthy ryegrasses for 20 d (latent period). They were again replaced for other healthy ryegrasses and were place in cages for 14,7, and 1 d (inoculation access period [IAP]). After IAP, these plants were moved into different insect-free cages for 30 d, after which polymerase chain reaction (PCR) analyses were carried out. Phytoplasma-free insects on ryegrasses were considered as control treatments. Furthermore, plant height and leaf area were recorded for all treatments. After PCR, 46,60, and 13% of the plants exposed to infected A. curtulus by 14,7, and 1 d of IAP, respectively, were infected with 'Ca. Phytoplasma ulmi'. Similarly, plants exposed to an IAP of 14, 7, and 1 d with phytoplasma-infected leafhoppers showed a reduction in plant height of 19,39, and 28% and leaf area of 302,169, and 55%, respectively, in comparison to those exposed to phytoplasma-free leafhoppers. We showed that A. curtulus has the ability to transmit phytoplasma from U. molinae to ryegrasses, affecting ryegrass plant height and leaf area. [ABSTRACT FROM AUTHOR]

Exitianus Ball, 1929 is studied from Tando Jam, Pakistan. Two species, Exitianus indicus (Distant, 1908) and Exitianus nanus (Distant, 1908), are reviewed and their characters, habitus, and line drawing are given. [ABSTRACT FROM AUTHOR]

Many insects rely on bacterial symbionts with tiny genomes specialized for provisioning nutrients lacking in host diets. Xylem sap and phloem sap are both deficient as insect diets, but differ dramatically in nutrient content, potentially affecting symbiont genome evolution. For sap-feeding insects, sequenced symbiont genomes are available only for phloem-feeding examples from the suborder Sternorrhyncha and xylem-feeding examples from the suborder Auchenorrhyncha, confounding comparisons. We sequenced genomes of the obligate symbionts, Sulcia muelleri and Nasuia deltocephalinicola, of the phloem-feeding pest insect, Macrosteles quadrilineatus (Auchenorrhyncha: Cicadellidae). Our results reveal that Nasuia-ALF has the smallest bacterial genome yet sequenced (112 kb), and that the Sulcia-ALF genome (190 kb) is smaller than that of Sulcia in other insect lineages. Together, these symbionts retain the capability to synthesize the 10 essential amino acids, as observed for several symbiont pairs from xylem-feeding Auchenorrhyncha. Nasuia retains genes enabling synthesis of two amino acids, DNA replication, transcription, and translation. Both symbionts have lost genes underlying ATP synthesis through oxidative phosphorylation, possibly as a consequence of the enriched sugar content of phloem. Shared genomic features, including reassignment of the UGA codon from Stop to tryptophan, and phylogenetic results suggest that Nasuia-ALF is most closely related to Zinderia, the betaproteobacterial symbiont of spittlebugs. Thus, Nasuia/Zinderia and Sulcia likely represent ancient associates that have co-resided in hosts since the divergence of leafhoppers and spittlebugs >200 Ma, and possibly since the origin of the Auchenorrhyncha, >260 Ma. [ABSTRACT FROM PUBLISHER]

We conducted studies in a Paso Robles, CA, grape (Vitis vinifera L.) vineyard in 2002 and 2003 to estimate the impact of regulated deficit irrigation (RDI) intensity and duration on western grape leafhopper, Erythroneura elegantula Osborn. Treatments were based on deficit intensity, 50 and 25% of standard irrigation (moderate and severe deficits, respectively), and deficit duration, 3 or 6 wk time, initiated at the grape phenological stage of berry set. The standard irrigation served as the control, and was intended to be as close to 100% of evapotranspiration (1.0 ETc) for grape in this area. Each week we took counts of leafhopper nymphs and estimated stomatal conductance, and at the end of each leafhopper generation we counted live, hatched and parasitized leafhopper eggs. Second generation leafhopper nymphal density was lowered by about 38 and 70% in 2002 and 2003, respectively, but in 2003 only the severe deficit had a negative effect on the third generation. This same pattern was seen in oviposition: second generation egg density was reduced by about 44% in the deficit treatments, but in the third generation only the severe deficit was lower than the control. There was little difference between the 3 vs. 6 wk duration in nymphal or egg density. The differences among treatments in second generation peak nymphal density were greater than the differences in second generation hatched eggs, suggesting that in addition to egg mortality, the deficits also affected nymphal mortality. Management strategies for maintaining leafhopper density low in the second generation and third generations include maintaining a sub-1.0 ETc irrigation strategy after the main RDI period, or reinstating the RDI to correspond to the third generation. [ABSTRACT FROM AUTHOR]

Three new submacropterous species of Splonia Signoret, 1891 are described and illustrated: Splonia dietrichi (Peru, new record for the genus), Splonia flavoscutellata (Ecuador), and Splonia fritilla (Venezuela). A detailed redescription of the genus is given, including the first account of the female terminalia (based on S. fritilla). A key to males of the now six known Splonia species is provided. [ABSTRACT FROM AUTHOR]

Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae) vectors Xylella fastidiosa, a bacterium causing Pierce's disease in grapevine. The development and reproductive biology of this economically important insect species were studied under greenhouse and laboratory conditions during the spring-summer and fall-winter and at different rearing densities. The greenhouse was heated during the cool months to match summer temperatures and photoperiods were enhanced artificially. Longevity was affected by sex and season, with winter individuals living significantly longer than summer males (6.5-fold) and females (two-fold). Vitellogenesis was delayed in fall female H. vitripennis and a higher variability in lifetime fecundities was also observed. Longevity and the factors influencing it such as environmental conditions and availability of food sources are key factors determining fecundity in H. vitripennis. Offspring performance (developmental time, survival) was moderate during the cool months, although development of nymphs to adulthood was ≈=13% greater. Rearing densities affected developmental time, survival, and egg production. Egg production per capita was higher in winter adults and the largest egg output was obtained at a rearing density of 100 nymphs per cage. Data presented herein suggest that nymph and adult H. vitripennis have evolved to ensure that only resistant stages are exposed to seasonal hazards. Captive adult females entered reproductive diapause in the fall as wild females would and despite warm greenhouse temperatures and long photoperiods and nymphal development decreased three- to six-fold during the fall-winter depending on rearing densities. These traits may be critical for the species to perpetuate in its native range. [ABSTRACT FROM AUTHOR]

The American grapevine leafhopper, Scaphoideus titanus Ball (Hemiptera: Cicadellidae), is the vector of the phytoplasma that causes Flavescence dorée, one of the most threatening grapevine yellows disease. The role of olfaction in host plant detection of this species is still unknown. In this study, the attractiveness of a host plant, the grapevine rootstock Vitis riparia X rupestris 101/14, to nymphs was verified through behavioral bioassays in a vertical glass Y-olfactoineter. Furthermore, the olfactory sensitivity to odors extracted from grapevine organs headspace and the external morphology of the antennae were studied by electroantennography (EAG) and scanning electron microscopy (SEM), respectively. Headspace collections were made from fresh apical shoots and leaves. Concentrated extracts were analyzed by coupled gas chromatography and mass spectrometry (GC-MS) to identify volatile compounds. In EAG experiments, weak responses to plant odors were recorded. SEM observations indicated the presence of few antennal sensilla, potentially associated with olfaction. Our results suggest that olfactory cues flay play a role in the host plant detection of S. titanus nymphs. [ABSTRACT FROM AUTHOR]

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Observations and comparative data are presented on the acoustic signals of three sharpshooter (Hemiptera: Auchenorrhyncha: Cicadellidae: Cicadellinae) species native to North America. The acoustic signals of the glassy-winged sharpshooter, Homalodisca vitripennis (Germar), native to the southeastern United States, are compared with two smaller sharpshooters native to the western United States, Homalodisca liturata Ball and blue-green sharpshooter, Graphocephala atropunctata (Signoret). Each sharpshooter is a known vector of the plant pathogenic bacterium Xylella fastidiosa Wells et at. Male acoustic signals from all three species and female signals from H. liturata and G. atropunctata were recorded from host plant substrates. The H. vitripennis calls were recorded in the evening and morning, whereas H. liturata and G. atropunctata were recorded in the afternoon. Each species has a characteristic acoustic signal of which the male call structure is most complex in H. vitripennis and simplest in H. liturata. Male-female acoustic duets in H. liturata and G. atropunctata were recorded, and distinct differences were found in the reply latencies between male and female calls in these species. [ABSTRACT FROM AUTHOR]

The anatomy and histology of female Homalodisca coagulata (Say) (Hemiptera: Cicadellida: Proconiini) reproductive organs is described using light microscopy. The reproductive organs of H. coagulata consist of one pair of ovaries, each with 10 telotrophic ovarioles, a pair of lateral oviducts, a common oviduct, a spermatheca, an enlarged genital duct, a complex bursa copulatrix, a vagina, two types of accessory glands, and a genital chamber. The reproductive organs follow the general pattern seen in cicadellids. The complex bursa copulatrix, important in copulation and sperm transfer, is described. A set of morphological criteria were selected, based on the stage of oocyte development, and used to evaluate and assign the rank of ovarian development for field-collected individuals and to assess the overall reproductive status of female insect populations. A principal component analysis of morphological and physiological characteristics suggests that the ovarian ranks reflect the reproductive status of the females. Understanding reproductive status and patterns is critical for determining the optimal time to implement control methods to suppress H. coagulata populations in southern California. [ABSTRACT FROM AUTHOR]

Female Homalodisca coagulata (Say) were collected from October 2001 to February 2005 from citrus at the University of California. Riverside. Between 5 and 20 females per sampling date were dissected, and each was assigned an ovarian rank: previtellogenic, vitellogenic, or postvitellogenic. Ovarian ranking was used to characterize H. coagulata reproductive activity. Results of these dissections revealed consistent annual patterns in the proportion of previtellogenic females present in this field population, These patterns indicate that there are two distinct generations annually, with an occasional third generation. A time-dependent model of H. coagulata vitellogenesis cycles in Riverside. CA. was developed, which makes it possible to predict the appearance of the subsequent generation based on previous observed peaks in the proportion of vitellogenic females. [ABSTRACT FROM AUTHOR]

The spatial distribution of the nymphs of Scaphoideus titanus Ball (Homoptera Cicadellidae), the vector of grapevine flavescence dorée (Candidatus Phytoplasma vitis, 16Sr-V), was studied by applying Taylor's power law. Studies were conducted from 2002 to 2005, in organic and conventional vineyards of Piedmont, northern Italy. Minimum sample size and fixed precision level stop lines were calculated to develop appropriate sampling plans. Model validation was performed, using independent field data, by means of Resampling Validation of Sample Plans (RVSP) resampling software. The nymphal distribution, analyzed via Taylor's power law, was aggregated, with b = 1.49. A sample of 32 plants was adequate at low pest densities with a precision level of D0 = 0.30; but for a more accurate estimate (D0 = 0.10), the required sample size needs to be 292 plants. Green's fixed precision level stop lines seem to be more suitable for field sampling: RVSP simulations of this sampling plan showed precision levels very close to the desired levels. However, at a prefixed precision level of 0.10, sampling would become too time-consuming, whereas a precision level of 0.25 is easily achievable. How these results could influence the correct application of the compulsory control of S. titanus and Flavescence dorée in Italy is discussed. [ABSTRACT FROM AUTHOR]

In 2003 and 2004, field studies were conducted at three sites in Zhejiang Province in China to assess the impacts of Bacillus thuringiensis (Bt) Berliner rice expressing a fused gene of cry1Ab and cry1Ac on nontarget planthoppers and leafhoppers. Populations in Bt plots were sampled with yellow sticky card traps, Malaise traps, and a vacuum-suction machine, and compared with samples from non-Bt control (IR72) plots. The results from yellow sticky card trap samplings indicated no significant differences between Bt and non-Bt plots in the species composition or densities of each species of planthopper and leafhopper. Three species of planthoppers, Sogatella furcifera (Horvath), Nilaparvata lugens (StAl), and Laodelphax striatellus (Fallen), were collected at all sites, and three species of leafhoppers, Nephotettix cincticeps (Uhier), Thaia subrufa (Motschulsky), and Recilia dorsalis (Motschulsky), were collected at Hangzhou. Another species of leafhopper, N. virescens (Distant), was collected at Anji and Jiande instead of T. subrufa. The results from the Malaise trap and vacuum-suction samples revealed no significant differences between Bt and non-Bt plots in species structure of planthoppers and leafhoppers or in population changes of the predominant planthopper species, S. furcifera, the predominant leafhopper species, N. cincticeps, or N. virescens throughout most sampling dates. Densities of planthoppers and leafhoppers were significantly affected by year and site but not by Bt rice, In general, our results suggest that the Bt rice line tested did not adversely affect nontarget planthopper and leafhopper populations and will not lead to higher populations or damage by planthoppers and leafhoppers. [ABSTRACT FROM AUTHOR]

The recent incursion of the sharpshooter Homalodisca coagulata (Say) (Hemiptera: Cicadellidae), a vector of the plant pathogenic bacterium Xylella fastidiosa, into southern California has caused new epidemics of plant diseases. The potential of H. coagulata to spread throughout the state and disseminate disease has encouraged the development of techniques to limit further spread of the vector and to manage disease epidemics where the insect already exists. We evaluated a unique tactic to curtail the immigration of H. coagulata into high-value crops, including nursery stock, where they can be spread via commercial transportation throughout the state and into disease-susceptible vineyards. This tactic consists of a 5-m-high screen barrier surrounding the crop that is impenetrable to H. coagulata. We examined H. coagulata orientation and flight direction when placed near or on the screen barrier, and determined the proportion of insects that flew over it. When released midway between a barrier and adjacent vegetation 71.5% of H. coagulata flew away from the barrier and in the direction of the vegetation; whereas 29.5% flew in the direction of the barrier. Of the total number of H. coagulata released, 7.5% flew over the barrier. When placed on the barrier, H. coagulata generally climbed up an average of 1.16 m before flying away from the structure. Of the total number of H. coagulata placed on the barrier, 6% flew over it. These results suggest that a screen barrier can be a part of a management strategy to reduce number of H. coagulata in high-value crops. [ABSTRACT FROM AUTHOR]

The Nearctic leafhopper genus Errhomus Oman (Hemiptera: Cicadellidae) exhibits high host-plant selectivity and female brachyptery, which may limit gene flow. Two subgenera, Errhomus (Errhomus) and Errhomus (Erronus), are recognized based on morphological and behavioral differences. We used mitochondrial DNA sequencing to elucidate the phylogenetic relationships among members of the subgenus Errhomus (Erronus). Portions of the NADH dehydrogenase subunit 1 (ND1) and the leucine (CUN) transfer RNA (tRNA-Leu) genes were sequenced and were analyzed with parsimony and maximum likelihood. Our results generally verified the findings of Hamilton and Zack (1999); however, both optimality criteria revealed a paraphyletic Errhomus (Erronus). Errhomus (Erronus) calvus does not seem to be a member of the subgenus Errhomus (Erronus) but seems to be more closely aligned with the subgenus Errhomus (Errhomus). We tested two a priori null hypotheses: 1) that the phylogeny estimated from the molecular data matched a previous phylogeny based on morphology and biogeography from Hamilton and Zack (1999) and 2) that diagnostic characters of the male genitalia (serrated aedeagal processes and triangular aedeagal shaft tip) were synapomorphies that defined major clades. We rejected these hypotheses with both Bayesian tests and parametric bootstraps. [ABSTRACT FROM AUTHOR]

Based on comparative morphology, the leafhopper tribe Grypotini Haupt 1929 is considered a junior synonym of Koebeliini Baker 1897 (new synonymy). Features uniting these taxa include ocelli below crown margin and not visible from above, distant from the compound eyes; anteclypeus long, narrow, and tapered; platellae present on the plantar surface of metathoracic tarsomere I; and nymphs with reduced abdominal chaetotaxy. Koebeliinae is considered a synonym of Deltocephalinae Dallas 1870, and Koebeliini is placed as a tribe within Deltocephalinae based largely on the male and female genitalia. Tribe Koebeliini as here defined includes subtribes Koebeliina, including only Koebelia Baker, and Grypotina, including Grypotes Fieber, Grypotellus Emeljanov, Pinopona Viraktamath and Sohi, Shivapona Ghauri and Viraktamath, and Sohipona Ghauri and Viraktamath. Thamnotettix sinae Stål is transferred to Pinopona. A redescription of Koebeliini and key to genera are provided. Species of this tribe seem to feed primarily on Pinus spp. (Pinaceae). Subtribe Koebeliina is restricted to the western Nearctic region. Species of Grypotina occur primarily in the Himalayan region, with two species distributed in the western Palearctic. [ABSTRACT FROM AUTHOR]

Diagnostic characters for the New World leafhopper subfamily Neocoelidiinae are reviewed. Krocodona Kramer (with new synonym Krocobella Kramer), Krocozzota Kramer, and the fossil genus Krocarites Dietrich and Vega, previously placed in Nirvaninae based on their depressed, strongly produced heads, are transferred to Neocoelidiinae (new placements) based on characters of the head, wing venation, leg chaetotaxy, and male genitalia. The related neocoelidiine leafhopper genera Retrolidia, new genus, based on three new species, and Krocolidia, new genus, based on two new species, all from South America; four new South American species of Krocodona; and a new species of nus) are described and illustrated. Keys to Krocodona and Retrolidia species and a checklist of neocoelidiine genera are provided. [ABSTRACT FROM AUTHOR]

The mollicute corn stunt spiroplasma (Spiroplasma kunkelii) is a leafhopper-transmitted pathogen of maize. Sequencing of the ∼1.6-Mb genome of S. kunkelii was initiated to aid understanding the genetic basis of spiroplasma interactions with their plant and leafhopper hosts. In total, 144 712 nucleotides of non-redundant, high-quality S. kunkelii genome sequence were obtained. Sequence tags were searched against the Mycoplasmataceae and Bacillus/Clostridium databases. Results showed that, in addition to spiroplasma phage SpV1 DNA insertions, spiroplasma genomes harbor more purine and amino acid biosynthesis, transcription regulation, cell envelope and DNA transport/binding genes than Mycoplasmataceae genomes. This investigation demonstrates that survey sequencing is an efficient procedure for gene discovery and genome characterization. The results of the S. kunkelii sequencing project are available at the Spiroplasma WebPage at http://www.oardc.ohio-state.edu/spiroplasma/genome.htm. [Copyright &y& Elsevier]

In recent years, we found that Hishimonus lamellatus Cai et Kuoh is a potential vector of jujube witches'-broom phytoplasma. However, little is known about the anatomy and histology of this leafhopper. Here, we examined histology and ultrastructure of the digestive system of H. lamellatus , both by dissecting and by semi- and ultrathin sectioning techniques. We found that the H. lamellatus digestive tract consists of an esophagus, a filter chamber, a conical midgut and midgut loop, Malpighian tubules, an ileum, and a rectum. Furthermore, both the basal region of the filter chamber epithelium and the apical surface of the midgut epithelium have developed microvilli. We also identify the perimicrovillar membrane, which ensheaths the microvilli of midgut loop enterocyte, and the flame-like luminal membrane, which covers the microvilli of the conical midgut epithelium. In addition, H. lamellatus has the principal and accessory salivary glands. Our observations also showed that the endoplasmic reticulum, mitochondria, and secretory granules were all highly abundant in the secretory cells of the principal salivary glands, while the accessory glands consist of only one ovate or elbow-like acinus. We also briefly contrast the structure of the gut of H. lamellatus with those of other leafhopper species. These results intend to offer help for the future study on the histological and subcellular levels of phytopathogen–leafhopper relationships, including transmission barriers and the binding sites of pathogens and other microorganisms within their leafhopper vectors. [ABSTRACT FROM AUTHOR]

North American Grapevine Yellows (NAGY) is a destructive disease of grapevines caused by phytoplasmas, wall-less bacteria that are insect-transmitted and found in plant phloem tissues. Although the disease was recognized in vineyards in the eastern United States since the 1980s, the identities of vectors remain unknown. The objectives of this study were to survey potential phytoplasma vector insects inhabiting Virginia vineyards that expressed NAGY symptoms and to evaluate their ability to transmit phytoplasmas associated with NAGY. Phytoplasmas were identified as ' Candidatus Phytoplasma pruni'-related NAGYIIIβ strains and ' Ca. Phytoplasma asteris'-related NAGYI-B strains. To determine the identities of the potential vectors, artificial feeding solution was used to evaluate the ability of leafhopper species to release phytoplasmas during feeding and phytoplasma strains were identified using molecular tools. Out of 49 insect species screened, Jikradia olitoria was the only insect that released phytoplasmas into the feeding solutions; all phytoplasmas, thus, detected were identified as NAGYIIIβ strains by nucleotide sequencing of three different genomic regions. No NAGYI-B strain was detected. To our knowledge, this is the first evidence of a potential insect vector of a specific phytoplasma associated with NAGY disease, and it is the first report of J. olitoria being a putative vector of a plant pathogenic phytoplasma. [ABSTRACT FROM AUTHOR]

Male and female aster leafhoppers, Macrosteles quaehihneatas Forbes,differ in their ability to transmit the aster yellows phvtoplasma. In laboratory and greenhouse experiments. Males were up to twice as likely as females to acquire and become infected with aster yellows phytoplasma as measured by polymerise chain reaction analysis. Yet, in 3different experimental arenas, infected females were significantly more likely than infected males to transmit aster yellows phytoplasma.When confined on single leaves, more females (55%) than males (.3.5%) transmitted phytoplasma to lettuce plants. In cages with access to 1 lettuce plants, females transmitted to 18% and males to 8`70 of theplants. When leafhoppers were released in the greenhouse, where leafhoppers were relatively unrestricted in their movement, females transmitted to 29.8% and males to 10.1% of lettuce plants. The pattern of spread by females in the greenhouse was significantly more clustered than that by males. The different movement and feeding behaviors of males and females may explain, in part, differences observed. We conclude that gender does matter in transmission of aster yellows phytoplasma by the aster leafhopper. [ABSTRACT FROM AUTHOR]

Alfalfa, Medicago saliva L., and 2 alfalfa-grass intercrops were sampled in 1995 and 1996 to determine the effect of intererops on alfalfa insect pests and associated insect predator populations. The 2 grasses intercropped with alfalfa were smooth bromegrass, Bronars incrrnis Leyss., and orchardgrass, Dactyli glornerata L. In the Ist forage crops. potato leafhopper, Empoasca flbac(Harris), numbers were significantly greater in the alfalfa iuonocultures than the 2 alfalfa-foragegrass into rcrops. Significantly greater numbers of alfalfa weevil, IhIpera postica (Gyllenhal), larvae were collected from alfalfa monocultures than alfalfa- orchardgrass intercrops, but monocultures were not significantly different from alfalfa- bromegrass intercrops. In the 2nd alfalfa crops, significantly greater numbers of potato leafhoppers were collected in the alfalfa monocultures compared with the alfalfa-orchardgrass intercrops. Significantly greater numbers of commondamsel bugs, Nabis americoferus Carayon, were collected on alfalfa monocultures compared with the intercrops, but no consistent significant differences were observed between alfalfa-grass intercrops and themonoculture. Alfalfa stand densities and biomass estimates were significantly greater in alfalfa monocultures than alfalfa-forage grass intercrops. In the lst and 2nd crops, orchardgrass densities and biomass were consistently larger than bromegrass. Few differences in totalbiomass were found among the treatments in either year. No significant differences in potato leafhopper and alfalfa weevil intensities onalfalfa plants were found among the treatments. The results of this study suggest that alfalfa-forage grass intercrops reduce insect pestpopulations compared with monocultures, but additional management tactics may be needed to reduce insect pest levels below economic thresholds. [ABSTRACT FROM AUTHOR]