Preferred name: Graphocephala atropunctata
Authority: (Signoret)
Taxonomic position: Animalia: Arthropoda: Hexapoda: Insecta: Hemiptera: Auchenorrhyncha: Cicadellidae
Other scientific names: Hordnia circellata (Baker), Neokolla circellata (Baker), Tettigonia atropunctata Signoret, Tettigonia circellata Baker
Common names in English: blue-green sharpshooter
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Notes on taxonomy and nomenclature EU Categorization: A1 Quarantine pest (Annex II A)
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EPPO Code: GRCPAT

Graphocephala atropunctata feeds on a wide variety of host plants, and unlike other common economically important leafhoppers, is often found feeding on perennials plants including vines, trees and shrubs (Hewitt et al., 1949). It has been collected from over 150 plant species, and in areas where population densities are high it may be found on other plant species including ornamental plants and weeds. G. atropunctata tends to be less abundant on ferns and grasses (Hewitt et al., 1949). The list of hosts includes records from both natural and greenhouse/laboratory settings (Hewitt et al., 1949; Freitag, 1951; Raju et al., 1983; Hopkins & Adlerz, 1988; Hill & Purcell, 1995; Purcell & Saunders, 1999; Wistrom & Purcell, 2005; EFSA, 2013).

Host list: Acacia longifolia, Acer macrophyllum, Aesculus californica, Amaranthus blitoides, Ambrosia acanthicarpa, Artemisia douglasiana, Artemisia vulgaris, Baccharis pilularis, Baccharis salicifolia, Cestrum elegans, Chenopodiastrum murale, Chenopodium album, Chenopodium quinoa, Cichorium intybus, Conium maculatum, Convolvulus arvensis, Coprosma baueri, Cyperus eragrostis, Cyperus esculentus, Dysphania ambrosioides, Erigeron canadensis, Eriochloa gracilis, Erodium moschatum, Eucalyptus camaldulensis, Eucalyptus globulus, Francoa sonchifolia, Fraxinus sp., Fuchsia hybrids, Genista monspessulana, Hedera canariensis, Hedera helix, Helianthus annuus, Ipomoea purpurea, Juglans californica, Juglans regia, Lactuca serriola, Limonium perezii, Malva parviflora, Mentha arvensis, Myoporum laetum, Parthenocissus tricuspidata, Pelargonium capitatum, Pelargonium peltatum, Pelargonium x domesticum, Pelargonium x hortorum, Pittosporum eugenioides, Populus fremontii, Portulaca oleracea, Quercus lobata, Quercus sp., Rosa californica, Rubus discolor, Rubus parviflorus, Rubus procerus, Rubus sp., Rubus ursinus, Rubus vitifolius, Rumex crispus, Salix sp., Salvia leucantha, Sambucus canadensis, Sambucus cerulea, Sambucus sp., Scrophularia californica, Simmondsia chinensis, Sonchus oleraceus, Sorghum halepense, Symphoricarpos albus var. laevigatus, Symphoricarpos albus, Syzygium australe, Toxicodendron diversilobum, Umbellularia californica, Urtica dioica subsp. gracilis, Urtica dioica, Urtica sp., Vicia faba, Vinca major, Vitis californica, Vitis rupestris, Vitis vinifera, Xanthium strumarium

Graphocephala atropunctata is found in the Western United States and as far south as Nicaragua. G. atropunctata prefers heavily vegetated areas along streams, rivers, and canyons (Delong & Severin, 1949). Although it requires damp conditions it does not thrive in overly wet or dark areas. This species can occur in very high densities within its preferred habitat.

North America: Mexico, United States of America (Arizona, California, Oregon, Texas)
Central America and Caribbean: Nicaragua

The female cuts a slit into the distal portions of a plant (or tendrils anywhere along the plant) and deposits a single egg which hatches between 16 and 22 days later (Severin, 1949a; Boyd & Hoddle, 2006). This contrasts with other common leafhopper grapevine pests which oviposit on the epidermal tissue on the undersides of leaves (Boyd & Hoddle, 2006). After hatching, the nymph will typically feed on the underside of leaves on the plant it emerged from. G. atropunctata typically has five instars (although some individuals can have 4 or 6 instars) and the total length of time spent in the nymphal stage (if feeding on grapevine) ranges from 47-51 days, with females taking longer to mature (Severin, 1949a). The time spent as a nymph can vary significantly on different host plants. In both Northern and Southern California, G. atropunctata has a single generation per year and adults overwinter before laying eggs in the spring (Severin, 1949a; Boyd and Hoddle, 2006). However, under some conditions a small second generation may be produced. In natural conditions, G. atropunctata can live from the summer of one year to the following spring. Under greenhouse conditions Severin (1949b) found that while there was a large range in longevity, the longest-lived males lived 129 days while the longest-lived female lived for 92 days. G. atropunctata can transmit X. fastidiosa which causes several diseases in a wide range of cultivated and wild host plants (EPPO, 2019).

Graphocephala atropunctata commonly feeds on perennial vegetation, and within its natural range several commonly used hedgerow species are among its preferred hosts.

Symptoms

Graphocephala atropunctata infestation is primarily identified by observation of adults or nymphs. Unlike other economically important sharpshooters, oviposition does not appear to result in noticeable blisters or other defects in the plant (Boyd & Hoddle, 2007).

Morphology

Eggs- little is known about the egg stage of G. atropunctata. Egg size and shape has not been described.

Larvae- Severin (1949) found that 1 day post hatching, nymphs ranged from 1.35 to 1.72 mm in length and between 4.72 and 5.39 mm one day after becoming a 5^th instar. He also found that nymphal size was non overlapping, under the conditions the study was performed in, so instars could be identified by size. Nymphs are primarily white but have a yellowish tinge on the sides of the abdomen.

Pupae- no pupal stage

Adults- Under greenhouse conditions, adult male size ranged from 5.6 to 6.0 mm while females were 6.0 to 6.8 mm long (from head to end of the body) (Severin, 1949a). The head plus wing length was slightly longer than body length (Severin, 1949a). In general, the vertex is rounded and yellowish (or yellowish green) with a black spot at the tip and additional dark marks on the head. However, this species exhibits large variations in colour related to latitude. In its current range, southern populations are primarily blue with several highly contrasting markings on their pronotum and head whereas northern populations are dark green or blueish green with less contrasty markings (Severin, 1949a; Ballman et al., 2011). Legs are yellow to bright orange (Baker 1898).

Detection and inspection methods

The oviposition location cannot be identified on a plant until either a nymph or parasitoid emerges (Boyd & Hoddle, 2007).

In the native range (North America) of G. atropunctata, double sided yellow sticky traps (with appropriate measures to prevent unintentional trapping of vertebrates) are placed in vineyards and surrounding vegetation, then checked weekly. Additionally, sweep netting or visual examination can be used to monitor for G. atropunctata.

Any plants for planting should be inspected for insects or imported from areas where G. atropunctata does not occur. There is no evidence that harvested fruits of any host are a threat, primarily because sharpshooters do not oviposit on fruits and adults are unlikely to remain associated with fruit during the harvest, processing, and transportation process (European Food Safety Authority, 2019).

Redak et al. (2004) identified G. atropunctata as having a high threat of becoming an invasive vector globally due to several characteristics. These include the fact it utilizes a wide range of host plants, including several commercially important ornamental species that are transported worldwide, and also because it occurs in diverse habitats and ecosystems. However, G. atropunctata appears to have limited dispersal capabilities as in its native range disease transmission is most likely to occur at the edges of agricultural areas close to its preferred natural habitat. It has been shown that both disease prevalence and G. atropunctata density declines with distance away from these natural areas (Daugherty et al., 2012).

Economic impact

In its native range, G. atropunctata is considered to be one of the primary vectors of Xylella fastidiosa. It is an extremely efficient transmitter of X. fastidiosa, can occur in high densities, and has a wide geographic range. However, due to its preference for riparian habitats, disease outbreaks tend to be limited to plants adjacent to these areas (Purcell, 1975). Severin (1949b) found that G. atropunctata successfully transmitted X. fastidiosa from infected to healthy grapevine 65 % of the time and healthy alfalfa 35 % of the time. However, it was unable to transmit the bacterium from infected alfalfa to healthy alfalfa. G. atropunctata has a short (2 hours or lower) latent period that extends to 7 hours for transmission between grapevines (Severin, 1949b). Additionally, Severin (1949b) found that infected individuals can continue to transmit the bacterium for virtually their entire adult life however it is unknown if they can retain the bacterium under natural conditions (e.g. while overwintering).

Control

In California, insecticides are the most common control method, although spraying can be limited to the edge areas. Surrounding vegetation can be replaced with plant species not conducive to oviposition which can drastically reduce G. atropunctata abundance in agricultural areas. However, in many areas this would cause severe environmental damage as the riparian areas that G. atropunctata prefers, are already under anthropogenic threat. Research suggests these pests fly relatively close to the ground (less than 5 m above the ground) and therefore the creation of natural or artificial barriers could prevent sharpshooters from entering agricultural areas. However, a study by Daugherty et al. (2012) found that using barriers (in this study trees) at the borders of vineyards significantly reduced the numbers of G. atropunctata in a few years, though there was no significant decrease in numbers in most years. However, they suggest applying insecticides to barriers could improve efficacy and could be preferable to applying insecticides directly to grapevine or other crops.

Two mymarids (Hymenoptera): Polynema sp. near eutettexi and Gonatocerus latipennis have been identified as egg parasitoids of G. atropunctata. In particular, Boyd & Hoddle (2006) identify Polynema sp. near eutettexi as a potentially important natural control agent within its native range and further show this taxon will not parasitize eggs laid by the beet leafhopper, Neoaliturus tenellus which is the typical host of P. eutettexi (Boyd et al., 2008).

Phytosanitary risk

G. atropunctata can transmit X. fastidiosa which causes several diseases in a wide range of cultivated and wild host plants (EPPO, 2019). G. atropunctata is listed primarily as a vector of Pierce’s Disease (Redak et al., 2004, EFSA PLH Panel, 2019). Greenhouse experiments have demonstrated it is a highly efficient vector, with a short latent period coupled with an extended period where insects can transmit the bacterium after exposure. Although Redak et al. (2004) considers G. atropunctata to be a likely candidate for establishing populations outside its native range, they determined that impacts would likely be limited to the local area. This is primarily due to observations within the native range where G. atropunctata tends to be limited to areas directly adjacent to riparian regions and similarly most disease transmission occurs on the edges, nearby the riparian zone. Due to its risk to Europe, G. atropunctata is listed as an EU A1 Quarantine pest (Annex II A) and is regulated as a quarantine pest in Moldova, Morocco and Tunisia, and as a A1 pest in Georgia, Switzerland, Türkiye and the United Kingdom (EPPO, 2024).

There are a range of phytosanitary measures that may be taken to reduce the risk of introduction and spread of G. atropunctata. These include pre-export inspections to ensure that consignments of host plants for planting are pest free. However, because it is currently not possible to identify oviposition sites, visual examination could miss viable eggs. Sourcing host plants for planting from pest free areas or in a pest-free place of production and phytosanitary certificates and plant passports are recommended measures.

Baker CF (1898) New Tettigoninae, with notes on others. Psyche: A Journal of Entomology 8, 285-286.

Ballman ES, Rugman-Jones PF, Stouthamer R & Hoddle MS (2011) Genetic structure of Graphocephala atropunctata (Hemiptera: Cicadellidae) populations across its natural range in California reveals isolation by distance. Journal of Economic Entomology 104, 279–287. https://doi.org/10.1603/EC10112

Boyd EA & Hoddle MS (2006) Oviposition and flight activity of the blue-green sharpshooter (Hemiptera: Cicadellidae) on southern California wild grape and first report of associated egg parasitoids. Annals of the Entomological Society of America 99, 1154-1164.

Boyd EA, Hoddle MS (2007) Host specificity testing of Gonatocerus spp. egg-parasitoids used in a classical biological control program against Homalodisca vitripennis: a retrospective analysis for non-target impacts in southern California. Biological Control 43, 56-70.

Boyd EA, Triapitsyn SV & Hoddle MS (2008) Taxonomic notes on Polynema eutettexi Girault (Hymenoptera: Mymaridae) and a similar species reared as an egg parasitoid of Graphocephala atropunctata (Signoret)(Hemiptera: Cicadellidae) in California. The Pan-Pacific Entomologist 84, 194-199.

Daugherty MP, Gruber BR, Almeida RP, Anderson MM, Cooper ML, Rasmussen YD & Weber EA (2012) Testing the efficacy of barrier plantings for limiting sharpshooter spread. American journal of enology and viticulture 63, 139-143.

Delong D & Severin H (1949) Characters, distribution, and food plants of leafhopper vectors of virus causing Pierce’s disease of grapevines. Hilgardia 19, 171-186. https://doi.org/10.3733/hilg.v19n06p171

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European Food Safety Authority PLH Panel (Panel on Plant Health), Bragard C, Dehnen-Schmutz K, Di Serio F, Gonthier P, Jacques M-A, Jaques Miret JA, Justesen AF, Magnusson CS, Milonas P, Navas-Cortes JA, Parnell S, Potting R, Reignault PL, Thulke H-H, Van der Werf W, Civera AV, Yuen J, Zappala L, Malumphy C, Lopes JRS, Czwienczek E & MacLeod A (2019) Scientific Opinion on the pest categorisation of non-EU Cicadomorpha vectors of Xylella spp. EFSA Journal 17, 5736. https://doi.org/10.2903/j.efsa.2019.5736

European Food Safety Authority (2013) Statement of EFSA on host plants, entry and spread pathways and risk reduction options for Xylella fastidiosa Wells et al. EFSA Journal 11, 3468.

Freitag JH (1951) Host range of the Pierce's disease virus of grapes as determined by insect transmission. Phytopathology 41, 920-932.

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Hill BL & Purcell AP (1995) Multiplication and movement of Xylella fastidiosa within grapevine and four other plants. Phytopathology 85, 1368-1372.

Hopkins DL, Adlerz WC (1988) Natural hosts of Xylella fastidiosa in Florida. Plant Disease 72, 429-431.

Purcell AH (1975) Role of the blue-green sharpshooter, Hordnia circellata, in the epidemiology of Pierce's disease of grapevines. Environmental Entomology 4, 745-752. https://doi.org/10.1093/ee/4.5.745

Purcell AH & Saunders SR (1999) Fate of Pierce's disease strains of Xylella fastidiosa in common riparian plants in California. Plant Disease 83, 825-830.

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Severin HP (1949a) Life history of the blue-green sharpshooter, Neokolla circellata. Hilgardia 19, 187-189.

Severin HP (1949b) Transmission of the virus of Pierce’s disease of grapevines by leafhoppers. Hilgardia 19, 190-206.

Weber E (2006) Evaluation of blue-green sharpshooter flight height. In Symposium Proceedings: Pierce’s Disease Research Symposium, pp. 27-29.

Wistrom C & Purcell AH (2005) The fate of Xylella fastidiosa in vineyard weeds and other alternate hosts in California. Plant Disease 89, 994-999.

This datasheet was prepared in 2024 by Therese A Catanach, Academy of Natural Sciences of Drexel University. Her valuable contribution is gratefully acknowledged.

EPPO (2024) Graphocephala atropunctata. EPPO datasheets on pests recommended for regulation. https://gd.eppo.int (accessed 2024-09-27)

This datasheet was first published online in 2024. It is maintained in an electronic format in the EPPO Global Database. The sections on 'Identity', ‘Hosts’, and 'Geographical distribution' are automatically updated from the database. For other sections, the date of last revision is indicated on the right.