Van Duzee Research Articles

Taxonomic revision of Achradocera Becker (Diptera: Dolichopodidae), with description of two new species

The New World genus Achradocera Becker, 1922 (Diptera: Dolichopodidae) is revised and includes the following 12 species: A. angustifacies Becker stat. rev. (= A. chilensis (Van Duzee) syn. nov. and A. edwardsi (Van Duzee) syn. nov.; Chile); A. apicalis (Aldrich) (Antigua, Dominica, Marquesas, Montserrat, St. Lucia, Tonga and French Polynesia); A. arcuata (Van Duzee) (western USA, Hawaii and Mexico); A. balin sp. nov. (Brazil); A. barbata (Loew) (eastern Canada and eastern USA); A. excavata (Van Duzee) (Bahamas, British Virgin Islands, Cuba, Dominican Republic, Jamaica and Puerto Rico); A. femoralis Becker (Colombia and Curaçao); A. gimli sp. nov. (Brazil, Bolivia and Trinidad and Tobago); A. insignis Parent (Brazil, Paraguay and Argentina); A. longiseta Parent (Argentina); A. meridionalis Becker (= A. contracta (Van Duzee) syn. nov. and A. shannoni (Van Duzee) syn. nov.; Mexico, Belize, Guatemala, El Salvador, Peru and Hawaii); and A. tuberculata (Van Duzee) (Brazil, Guyana, Trinidad and Tobago and Venezuela). All valid species and their diagnostic features are fully photographed, a key to males is provided and the known distribution of each species is mapped.

A new species of planthopper in the genus Colpoptera (Hemiptera: Fulgoroidea: Nogodinidae) from the Northeastern coast of Jamaica

A new species of Colpoptera Burmeister, 1835, C. japortla sp. nov. (Colpopterinae: Colpopterini), is described from Jamaica. The new species was found during a survey of planthoppers associated with coconut palms to document taxa that are potential phytoplasma vectors. Molecular data for the five-prime region of the cytochrome c oxidase subunit I (COI) gene and 18S rRNA gene is provided and compared to available members of Colpopterini. Syntypes of Colpoptera rugosa Van Duzee borrowed for comparison with the new species were found to be a mixed series including representatives of Jamaha elevans (Walker). A lectotype designation, with an amended diagnosis, is made for Colpoptera rugosa, to preserve the stability of nomenclature and this species is transferred to Jamaha as J. rugosa, comb. nov.

On the identity of three species of Chrysotus Meigen (Diptera: Dolichopodidae) described from Brazil by Millard C. Van Duzee

The identity of three species of Chrysotus Meigen (Diptera: Dolichopodidae) described by Millard Carr Van Duzee is clarified. Chrysotus brasiliensis Van Duzee (Brazil: Mato Grosso) is transferred to the genus Micromorphus Mik; C. parvipalpus Van Duzee (Brazil: Amazonas, Maranhão and Pernambuco) is redescribed and assumed to be closely related to C. antillensis Runyon (West Indies) and C. duzeei sp. nov. (Brazil: Roraima and Mato Grosso do Sul); and C. setosus Van Duzee (=C. neotropicus Dyte) is regarded as a junior-synonym of C. hirsutus Aldrich (Lesser Antilles, Dominica, Costa Rica, Peru, and newly recorded from Brazil: Pernambuco and Alagoas). In addition, C. brevitibia Van Duzee, previously known from Puerto Rico, Dominica and Argentina, is newly recorded from Brazil (Mato Grosso do Sul).

Cultural control methods improve management of leafhopper vector of X-disease

X-disease, caused by the phytoplasma ‘Candidatus Phytoplasma pruni’, is currently threatening Pacific Northwest (USA) stone fruit (Prunus) production, particularly sweet cherry (P. avium). There is no cure, and infected fruit remain unmarketable throughout the tree's life. Management efforts focus on reducing transmission through infected tree removal and frequent chemical applications to control the leafhopper vectors. The increase in chemical inputs has broken down stone fruit integrated pest management techniques and is neither economically nor environmentally sustainable. To investigate sustainable vector management, we assessed the efficacy of two long-lasting cultural management techniques, kaolin clay (Surround WP) and reflective plastic geotextile (Extenday), to deter leafhoppers from trees and prevent population growth within orchards. These methods were tested against untreated control plots in Washington State commercial stone fruit blocks in 2021 and 2022. Colladonus montanus reductus (Van Duzee) was the most abundant leafhopper vector species captured in both years. In cherry blocks, Extenday consistently reduced C. m. reductus densities by 80–90%, while kaolin clay caused a 45–50% reduction in leafhoppers, but only when they were abundant (more than 10 leafhoppers per trap). Sticky cards placed at varying heights revealed that kaolin clay caused C. m. reductus to be proportionally more abundant near the ground cover than in the tree canopy regardless of overall population density. The combination of reducing C. m. reductus density and shifting their distribution into the ground cover demonstrates both plastic geotextiles and kaolin clay provide effective post-harvest strategies for X-disease vector management.

Phylogeny of North Americas largest cicada radiation redefines Tibicinoides and Okanagana (Hemiptera: Auchenorrhyncha: Cicadidae: Tibicininae).

Tibicinoides, with three small endemic California cicada species, has a confusing, intertwined systematic history with Okanagana that we unravel here. An ingroup including all species of Tibicinoides and the majority (84.7%) of Okanagana species were sampled for six gene regions, polarized with Clidophleps, Okanagodes, Subpsaltria, and Tibicina outgroups, and subjected to Bayesian phylogenetic analysis. Although the ingroup was monophyletic from all outgroups including Tibicina, Tibicinoides rendered Okanagana paraphyletic among two major ingroup clades. To bring classification into agreement with phylogeny, we redescribe and redefine Tibicinoides to include all Okanagana species with a hooked uncus in the male genitalia, all of which grouped with the type T. cupreosparsa (Uhler, 1889) in the first of these clades: T. boweni (Chatfield-Taylor & Cole, 2020) comb. n., T. catalina (Davis, 1936) comb. n., T. hesperia (Uhler, 1876) comb. n., T. mercedita (Davis, 1915), T. minuta (Davis, 1915), T. pallidula (Davis, 1917a) comb. n., T. pernix (Bliven, 1964) comb. n., T. rubrovenosa (Davis, 1915) comb. n., T. simulata (Davis, 1921) comb. n., T. striatipes (Haldeman, 1852) comb. n., T. uncinata (Van Duzee, 1915) comb. n., T. utahensis (Davis, 1919) comb. n., and T. vanduzeei (Distant, 1914) comb. n. Okanagana is redescribed and restricted to the species of the second major clade which contained the type O. rimosa (Say, 1830). We describe two new genera for morphologically distinct orphan lineages: Chlorocanta gen. nov. for C. viridis (Davis, 1918) comb. n. and Hewlettia gen. nov. for H. nigriviridis (Davis, 1921) comb. n. We recognize O. rubrobasalis Davis, 1926 stat. rev. as a species and relegate two former species to junior subjective synonyms: O. noveboracensis (Emmons, 1854) = O. canadensis (Provancher, 1889) and O. occidentalis (Walker in Lord, 1866) = O. lurida Davis, 1919. Tibicinoides and Okanagana together represent a rapid radiation that presents challenges to phylogenetic analysis including suboptimal outgroups and short internodes.

DNA degradation in Haplaxius crudus (Hemiptera: Cixiidae) and Diaphorina citri (Hemiptera: Liviidae) on yellow sticky traps in Florida.

Lethal bronzing (LB) and huanglongbing (HLB) are harmful plant diseases causing significant economic losses in Florida agriculture. Both diseases are caused by bacteria that are transmitted by Hemipteran insect vectors. Accurate detection of pathogens within insect vectors can help provide a better understanding of disease epidemiology. Monitoring of the vector of LB is done primarily using sticky traps within palm canopies. However, it is unknown how long pathogen and vector DNA remain intact under field conditions. If significant DNA degradation takes place over the course of days or weeks, there is a possibility of false negatives occurring when detecting pathogens from these surveys. This study determined how long Haplaxius crudus Van Duzee (Hemiptera: Cixiidae) and LB DNA could remain detectable on sticky traps under field conditions in Florida in winter and summer, using PCR and qPCR. Additionally, this study compared the DNA degradation of Diaphorina citri Kuwayama (Hemiptera: Liviidae) and Candidatus Liberibacter asiaticus (CLas), the causal agent of HLB. The results showed that DNA concentration and amplification rate declined as time on sticky traps increased. Degradation varied between different target genes. The amplification rate of insect genes from sticky trap samples suggests that sticky traps should be changed weekly in summer, and every 2 wk in winter for accurate H. crudus detection. Traps should be changed every 4 days for phytoplasma detection. Traps can be changed monthly for accurate D. citri and CLas detection. Based on these results, standard monitoring protocols can be implemented to more accurately detect vectors and pathogens.

Eight new species of Costanana DeLong & Freytag (Hemiptera: Cicadellidae: Gyponini): taxonomic changes, key to males, and description of Metacostana gen. nov.

Costanana DeLong & Freytag, 1972 is a Neotropical genus of leafhoppers currently comprising 13 species with a wide distribution from Mexico to Argentina. In this study, eight new species of Costanana are described, C. xenomorpha sp. nov. from Department of Cuzco, Peru, and seven Brazilian species: C. alata sp. nov. from Minas Gerais State; C. bifida sp. nov. from Paraná and Mato Grosso states; C. cifi sp. nov., C. obtusa sp. nov. and C. piraquarensis from Paraná State; C. luzi sp. nov. from Distrito Federal; and C. rubromarginata sp. nov. from Mato Grosso and Pará states. We propose that Costanana cella DeLong & Freytag, 1972 is a junior synonym of C. praecellens (Stål, 1862) and C. asymmetrica DeLong & Freytag, 1972 is a junior synonym of Gypona viridans DeLong & Martinson, 1972. Costanana costata DeLong & Freytag, 1972 and C. flavicosta (Stål, 1862) are transferred to Gypona Germar, 1821, C. minuta (Spångberg, 1878) is transferred to Acuponana DeLong & Freytag, 1970 and Gypona nupera Van Duzee, 1907 is transferred to Costanana. Gypona costata comb. nov. and Costanana santana DeLong & Wolda, 1983 are newly recorded from Pernambuco State, and Gypona flavicosta comb. nov. is recorded from Espírito Santo and Paraná states, Brazil. The female genitalia of Costanana flavina DeLong & Freytag, 1972, C. praecellens and Gypona flavicosta comb. nov. are described and illustrated for the first time and a brief note on feeding behavior is given for C. flavina and C. praecellens. A key to males and a new diagnosis are provided for Costanana. We also describe and illustrate Metacostana cornuta gen. et sp. nov., a new Brazilian genus for Gyponini sharing characteristics with Costanana, Acuthana Domahovski & Cavichioli, 2018, Domahovana Silva et al., 2022 and Dumorpha DeLong & Freytag, 1975.

Review of Paraclius arcuatus species-group (Diptera, Dolichopodidae) with description of two new species.

The Paraclius arcuatus species-group is reviewed and includes the following seven species: P. angusticauda Van Duzee, 1933, P. angustipennis Van Duzee, 1929, P. arcuatus (Loew, 1861), P. brooksi sp. nov., P. elongatus Van Duzee, 1930, P. pumilio Loew, 1872, and P. xibun sp. nov. Paraclius angustipennis, P. arcuatus and P. pumilio are redescribed based on photographs of types and additional specimens. Paraclius femoratus Aldrich, 1901 is synonymized with P. arcuatus, syn. nov. and Paraclius magnicornis Van Duzee, 1927 is regarded as a junior synonym of P. pumilio, syn. nov. An identification key, distribution maps and high-resolution photographs of species are provided. In addition, the systematic position of Paraclius is discussed.

Untangling the assassin's web: Phylogeny and classification of the spider‐associated Emesine complex (Hemiptera: Reduviidae)

AbstractWeb‐building spiders are formidable predators, yet assassin bugs in the Emesine Complex (Hemiptera: Reduviidae: Emesinae, Saicinae, and Visayanocorinae) prey on spiders. The Emesine Complex comprises >1000 species and these web‐associated predatory strategies may have driven their diversification. However, lack of natural history data and a robust phylogenetic framework currently preclude tests of this hypothesis. We combine Sanger (207 taxa, 3865 bp) and high‐throughput sequencing data (15 taxa, 381 loci) to generate the first taxon‐ and data‐rich phylogeny for this group. We discover rampant paraphyly among subfamilies and tribes, necessitating revisions to the classification. We use ancestral character state reconstructions for 40 morphological characters to identify diagnostic features for a revised classification. Our new classification treats Saicinae Stål and Visayanocorinae Miller as junior synonyms of Emesinae Amyot and Serville, synonymizes the emesine tribes Ploiariolini Van Duzee and Metapterini Stål with Emesini Amyot and Serville, and recognises six tribes within Emesinae (Collartidini Wygodzinsky, Emesini, Leistarchini Stål, Oncerotrachelini trib.n., Saicini Stål stat.n., and Visayanocorini Miller stat.n.). We show that a pretarsal structure putatively involved in web‐associated behaviours evolved in the last common ancestor of Emesini, the most species‐rich clade within Emesinae, suggesting that web‐associations could be widespread in Emesinae.

New or little-known Neotropical Dolichopodidae (Diptera) (II): genus Hercostomus Loew excluded from the Neotropics

The Neotropical species of Hercostomus Loew are revised and the following new combinations are proposed: Paraclius panamensis (Van Duzee, 1931) comb. nov. (Panama), P. plumitarsis (Parent, 1931) comb. nov. (Bolivia), P. problematicus (Parent, 1930) comb. nov. (Brazil and Guyana) and Tachytrechus flavimanus (Van Duzee, 1934) comb. nov. (Brazil, Ecuador and Guyana). The type of Hercostomus petulans Parent, 1939 is lost, the species cannot be confidently identified and is here treated as a nomen dubium. As a result, the genus Hercostomus is formally excluded from the Neotropical Region. Paraclius problematicus comb. nov., P. latipes (Aldrich) and Tachytrechus flavimanus comb. nov. are redescribed based on additional material and photographs of type specimens. In addition, Paraclius maculipennis (Van Duzee, 1934) is regarded as a junior synonym of P. problematicus comb. nov. A new species of Paraclius from Costa Rica, P. norrbomi sp. nov. is described in the newly proposed latipes-group, along with P. aberrans Robinson, P. latipes and P. panamensis comb. nov.

Bacterial Endosymbionts Identified From Leafhopper (Hemiptera: Cicadellidae) Vectors of Phytoplasmas.

Insects often harbor bacterial endosymbionts that provide them with nutritional benefit or with protection against natural enemies, plant defenses, insecticides, and abiotic stresses. Certain endosymbionts may also alter acquisition and transmission of plant pathogens by insect vectors. We identified bacterial endosymbionts from four leafhopper vectors (Hemiptera: Cicadellidae) of 'Candidatus Phytoplasma' species by direct sequencing 16S rDNA and confirmed endosymbiont presence and identity by species-specific conventional PCR. We examined three vectors of Ca. Phytoplasma pruni, causal agent of cherry X-disease [Colladonus geminatus (Van Duzee), Colladonus montanus reductus (Van Duzee), Euscelidius variegatus (Kirschbaum)] - and a vector of Ca. Phytoplasma trifolii, the causal agent of potato purple top disease [Circulifer tenellus (Baker)]. Direct sequencing of 16S identified the two obligate endosymbionts of leafhoppers, 'Ca. Sulcia' and 'Ca. Nasuia', which are known to produce essential amino acids lacking in the leafhoppers' phloem sap diet. About 57% of C. geminatus also harbored endosymbiotic Rickettsia. We identified 'Ca. Yamatotoia cicadellidicola' in Euscelidius variegatus, providing just the second host record for this endosymbiont. Circulifer tenellus harbored the facultative endosymbiont Wolbachia, although the average infection rate was only 13% and all males were Wolbachia-uninfected. A significantly greater percentage of Wolbachia-infected Ci. tenellus adults than uninfected adults carried Ca. P. trifolii, suggesting that Wolbachia may increase this insect's ability to tolerate or acquire this pathogen. Results of our study provide a foundation for continued work on interactions between leafhoppers, bacterial endosymbionts, and phytoplasma.

Two new genera and six new species of Terrestrial Hydrometridae (Hemiptera: Heteroptera) from French Polynesia

The family Hydrometridae (Hemiptera: Heteroptera) has been previously recorded from French Polynesia based on three species in three genera: Chaetometra robusta (Hungerford, 1939) and Dolichocephalometra pacifica (Van Duzee, 1934) from the Marquesas Islands, and Hydrometra gagnei J. Polhemus & D. Polhemus, 1995 from Tahiti in the Society Islands. Based on recent surveys from montane cloud forest habitats, two new genera and and six new species of Hydrometridae are described from the Marquesas and Society Islands as follows: Marquesametra n. gen. from the Marquesas Islands, containing M. hivaoa n. sp. from Hiva Oa (Mt. Temetiu); and Prohydrometra n. gen. from the Society Islands, containing the previously described P. gagnei n. comb. from Tahiti (Tahiti Nui), and the five new species P. johnpolhemi n. sp. and P. englundi n. sp. from Raiatea (Trois Cascade and Mt. Toomaru respectively); P. tohiea n. sp. and P. moorea n. sp. from Moorea (both from Mt. Tohiea); and P. teatara n. sp. from Tahiti (Mts. Teatara). All of these new species are terrestrial, and with the exception of P. johnpolhemi, which inhabits rheocrenes, represent specialized inhabitants of upland wet forest habitats. This indicates that terrestrial ecologies have evolved multiple times within the Hydrometridae, and are the typical mode of life for species of this family occurring in the insular eastern Pacific.

Two New Species of Hoplinine Stilt Bugs (Heteroptera: Berytidae: Gampsocorinae) from Brazil, with New Country Records for Three Other Species

The hoplinine stilt bugs (Heteroptera: Berytidae: Gampsocorinae) Hoplinus cincospinus Henry, new species from Minas Gerais, Brazil, and Parajalysus brunneus Henry, new species from Pará, Brazil, are described. A diagnosis, description, and digital images of the adult and selected structures are provided for each species and a revised key to the species of Hoplinus and a partial key to the species of Parajalysus are given to aid identification. New country records are given for Parajalysus punctipes Van Duzee, P. tenuicornis Henry, and P. verucosus Štusák.

Revisiting Stål's thoughts: formalizing the ictericus group in Euschistus (Euschistus) (Hemiptera: Heteroptera: Pentatomidae)

Euschistus Dallas is distributed throughout the Western Hemisphere and is composed of 67 species in three subgenera: Euschistomorphus Jensen-Haarup, Lycipta Stl, and the nominate subgenus. Euschistus (Euschistus) includes several economically important species. Due to the lack of a phylogenetic analysis for the subgenus Euschistus, its groupings are based primarily on male genitalia. In this paper, the following Nearctic taxa that were first grouped together by Stl (1872), namely E. ictericus (Linnaeus), E. variolarius (Palisot de Beauvois), E. servus servus (Say), E. servus euschistoides (Vollenhoven), and E. tristigmus tristigmus (Say), are reviewed and redescribed. Several other similar, and probably related, taxa are also included in this study: E. tristigmus luridus (Dallas), E. inflatus Van Duzee, and E. latimarginatus Zimmer. Morphological patterns pertaining to the internal and external male and female genitalia allowed us to formalize the ictericus group to include the above-mentioned species (except E. tristigmus). The morphological overlap between the subspecies and sympatric areas of distribution have led us to consider E. servus euschistoides as a junior synonym of E. servus servus, and to corroborate the synonymy first proposed by Uhler (1861) of E. tristigmus luridus under E. tristigmus tristigmus.

First record of the bow-legged bug, Hyalymenus subinermis Van Duzee, 1923 (Hemiptera: Heteroptera: Alydidae), in California, with description of the mimetic immature stages

The bow-legged bug genus Hyalymenus Amyot & Serville, 1843 (Hemiptera: Heteroptera: Coreoidea: Alydidae) includes 20 New World species. Of these, nymphs of only one species, H. tarsatus (Fabricius, 1803), have been described, and the description was restricted to the fifth instar. Nine specimens of H. subinermis Van Duzee, 1923, representing the first through the fifth instars, were collected on two Schinus terebinthifolia Raddi (Anacardiaceae) shrubs from a residential neighborhood (approximately 177,828 m2 surveyed) in Long Beach, California, U.S.A. in June 2021. Several other locations within the city were surveyed (i.e., parks, residential areas, and riparian habitats; approximately 109,177 m2 surveyed, collectively), but this species was not observed on other S. terebinthifolia plants or other plant species in these areas. Here, we give the first California record for H. subinermis, describe the five nymphal instars, provide habitus images of each instar, and discuss the distribution of the species in California, known host plants, and putative ant models that nymphs may mimic.

Directed Sequencing of Plant Specific DNA Identifies the Dietary History of Four Species of Auchenorrhyncha (Hemiptera)

Abstract Auchenorrhyncha (Hemiptera) includes several families of sap-feeding insects that tend to feed on a wide-range of host plants. Some species within Auchenorrhyncha are major agricultural pests that transmit plant pathogens or cause direct feeding damage. Nearly all pest Auchenorrhyncha are highly polyphagous, have mobile nymphs, and colonize crops from noncrop habitats. We examined whether methods for gut content analysis developed for more specialized Hemiptera identify dietary history of polyphagous Auchenorrhyncha. We used high-throughput sequencing of the plant genes trnF and ITS to examine the dietary history of Circulifer tenellus (Baker) (Cicadellidae), Colladonus geminatus (Van Duzee) (Cicadellidae), Colladonus montanus reductus (Van Duzee) (Cicadellidae), and Lycorma delicatula (White) (Fulgoridae). C. tenellus is a vector of the vegetable pathogens Candidatus Phytoplasma trifolii and beat curly top virus. Both Colladonus species are vectors of Ca. Phytoplasma pruni, the pathogen associated with X-disease of stone fruits. Lycorma delicatula is an invasive pest of grape and ornamentals in the eastern United States. Results showed spring hosts for C. tenellus included Brassicaceae, especially Sisymbrium sp. (tumble mustard), and spring hosts for both Colladonus species included Taraxacum sp. (dandelion). Gut content analysis also detected a decrease in host-breadth by L. delicatula from early to late instars. Results demonstrate that directed sequencing of plant DNA identified the dietary history of leafhopper and planthopper pests. Expanded use of gut content analysis will help identify the noncrop sources of phytoplasma-infected C. tenellus and Colladonus, and to examine seasonal changes in host shifts by L. delicatula.

Illustrated key to the species in the genus Sephina (Hemiptera: Heteroptera: Coreidae: Coreinae: Spartocerini), with descriptions of three new species and new distributional records.

Three new species of Sephina Amyot and Serville 1843, are described: S. crassa from Ecuador, S. effrena from Colombia and S. ornata from Panama. A key to the 27 known species and photographs of the dorsal habitus are included. Also included are photographs of the male genital capsule of S. vinula Stl 1862, and parameres of S. indierae Wolcott 1924 and S. vinula. New distributional records for S. dorsalis (White 1842), S. esquivelae Brailovsky Schez 1983, S. faceta Brailovsky 2001, S. formosa (Dallas 1852), S. geniculata Distant 1881, S. limbata Stl 1862, S. nigripes Schmidt 1907, S. pagella Brailovsky Schez 1983, S. pubera (Erichson 1848), S. pustulata (Fabricius 1803), S. rogersi Distant 1881, S. subulata Brailovsky Schez 1983, and S. vinula are included. Sephina excellens Schmidt, 1907 is synonymized under S. pubera (Erichson 1848). The synonymy of Sephina grayi Van Duzee, 1909 under S. gundlachi (Gurin-Meville 1857) is here corroborated.

The American Palm Cixiid, Haplaxius crudus

The American palm cixiid, Haplaxius crudus, is a common species of insect that belongs to the order Hemiptera, family Cixiidae. It is widespread and abundant in the state of Florida, but also occurs as far north as South Carolina and as far west as Texas. Furthermore, it is common throughout the Caribbean basin. This insect feeds on a wide variety of palm species as adults while the immature stages feed on a wide variety of grass species. This species is of high economic concern due to its ability to transmit the lethal yellowing (LY) phytoplasma (Howard and Thomas 1980) and is also the putative vector of lethal bronzing (LB) in Florida.
 
 Major revision of Howard, Forrest. 2007. “American Palm Cixiid, Myndus Crudus Van Duzee (Insecta: Hemiptera: Auchenorrhyncha: Fulgoroidea: Cixiidae)”. EDIS 2007 (10). https://journals.flvc.org/edis/article/view/116586. Revised 2015.

Use of Ground Covers to Control Three-Cornered Alfalfa Hopper, Spissistilus festinus (Hemiptera: Membracidae), and Other Suspected Vectors of Grapevine Red Blotch Virus

Grapevine red blotch virus (GRBV) is the causal agent of grapevine red blotch disease, which affects wine grapes and leads to reduced crop yield and quality. The pathogen-plant-vector relationship of GRBV is not well understood; however, some possible vectors have been identified: Caladonus coquilletti (Van Duzee; Hemiptera: Cicadellidae), Colladonus reductus (Van Duzee; Hemiptera: Cicadellidae), Erythroneura spp., Melanoliarus sp. (Hemiptera: Cixiidae), Osbornellus borealis DeLong. & Mohr (Hemiptera: Cicadellidae), Scaphytopius granticus (Ball; Hemiptera: Cicadellidae), Spissistilus festinus (Say). Of these species, S. festinus has been shown to transmit the virus to uninfected grapevines, making it of particular interest. Since the pathogen-plant-vector relationship of GRBV is not yet completely understood, pesticide use is not necessarily the best way to manage these possible vectors. Here we test if ground cover removal, by discing in spring, could reduce the activity of potential GRBV vectors. We show that S. festinus presence in the canopy was reduced in disc rows compared to just mowing the ground vegetation, whereas there were no differences in presence in the canopy between disc and mow rows of the other possible insect vectors. Erythroneura elegantula (Osborn; Hemiptera: Cicadellidae), a common pest of grapevines but not a candidate GRBV vector, was found to have higher densities in the canopy in disc rows compared to mow rows, an effect possibly mediated by changes in vine vigor associated with ground covers. We conclude that if S. festinus is a primary vector of GRBV, discing ground covers in early spring may be a viable way to reduce their presence in the vine canopy.

Remarkable Species Diversity of the Leafhopper Genus Xestocephalus (Hemiptera: Cicadellidae: Aphrodinae) in Thailand.

Simple SummaryThailand, a country on the Indochinese peninsula in Southeast Asia, is part of a biodiversity hot spot that harbors a large number of endemic species. The insect fauna remains poorly known, but a recent bioinventory has provided many new specimens for study. We review the common, widespread leafhopper genus Xestocephalus from Thailand and provide detailed morphological descriptions (the main evidence distinguishing species) and distributions of all species. Seventeen species were recognized, including twelve new species and four species recorded in Thailand for the first time.Xestocephalus Van Duzee is among the most common and widespread genera of Cicadellidae in the temperate and tropical regions of the world. In the present study, 205 specimens of the genus Xestocephalus were collected in Thailand, whereas only a single species of the genus was recorded previously using Malaise trap field sampling, studied by comparative morphology. Seventeen species were recognized, including twelve new species: X. binarius sp. nov., X. chrysanthemum sp. nov., X. cowboyocreus sp. nov., X. densprint sp. nov., X. dimiprocessus sp. nov., X. exproiecturus sp. nov., X. gracilus sp. nov., X. limpidissimus sp. nov., X. malleus sp. nov., X. nonattribus sp. nov., X. recipinams sp. nov., and X. tenusis Liang sp. nov. Four species were recorded in Thailand for the first time: Xestocephalus abyssinicus Heller and Linnavuori, Xestocephalus asper Linnavuori, Xestocephalus ishidae Matsumura, and Xestocephalus toroensis Matsumura. Detailed morphological descriptions of all 17 species are given; photographs of external habitus and male genitalia of the species from Thailand are provided. A checklist of species of the genus is also given, and a key to all Thailand Xestocephalus species is also provided.