3746_Layout 1 26/02/2015 17:40 Page 1 Entomologist’s Monthly Magazine 151 : 0 –0 Five invasive mealybug species new for Ascension Island (Hemiptera: Pseudococcidae), with a revised checklist of scale insects for the island BY CHRIS MALUMPHY, LIZA F. WHITE, JAYNE HALL, JENNIFER HODGETTS & MARTIN HAMILTON CM*, JH, JH: The Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, U.K.; email: [email protected] MH: Royal Botanic Gardens, Kew, Richmond, Surrey. TW9 3AB, U.K. LW: Ascension Island Government, Georgetown, Ascension Island, ASCN IZZ Accepted: January 9th , 2015 ABSTRACT Five invasive mealybug species are recorded for the first time from Ascension Island: Antonina graminis (Maskell) was collected from Cyperus appendiculatus ; Chorizococcus rostellum (Lobdell) from Sporobolus caespitosus ; Dysmicoccus brevipes (Cockerell) from C. appendiculatus ; Phenacoccus solani Ferris from Euphorbia origanoides and Portulaca oleracea ; and Planococcus minor (Maskell) from E. origanoides . Two of these host plants, E. origanoides and S. caespitosus , are endemic to Ascension Island and classed as ‘Critically Endangered’ on the International Union for the Conservation of Nature (IUCN) Red List. The biology, host range, distribution and economic importance of these mealybugs are reviewed, and their potential impact discussed. An updated and revised checklist of scale insects of Ascension Island is presented in an appendix. Keywords: plant health, invasive species, biosecurity, UK Overseas Territory, South Atlantic INTRODUCTION Ascension Island is a small (total area of 97 km 2), geologically young (1 million years), extremely isolated, volcanic island located in the equatorial waters of the South Atlantic Ocean (7º56′S, 14º22′W), approximately 1,600km from the coast of Africa and 2,250km from the coast of South America. It is governed as part of the UK Overseas Territory (UKOT) of Saint Helena, Ascension and Tristan da Cunha. During the 19th Century many species of plants, including tropical and European crops, were introduced to Ascension Island from the Royal Botanic Gardens, Kew, UK (Kew), and Cape Town, South Africa. Approximately 300 species of vascular plants were introduced, both deliberately and accidently (Cronk, 1980), which eventually dominated most of the island’s native plant communities. Inevitably, invasive plant pests were introduced along with their host plants. Colonisation of the island by non-native plants and animals pushed some of the endemic species, such as Oldenlandia adscensionis (DC.) Cronk, to extinction (Lambdon et al ., 2012b). Some species previously thought to be extinct, have been rediscovered during recent botanical surveys; for example, the Ascension Island parsley fern Anogramma ascensionis (Hook.) Diels was rediscovered in 2009 growing on unstable cliff faces (Lambdon et al ., 2010). Scale insects (Hemiptera: Coccoidea) are one of the most commonly transported groups of arthropods in international plant trade and among the most successful *corresponding author 3746_Layout 1 26/02/2015 17:40 Page 2 0 Entomologist’s Monthly Magazine (2015) Vol. 151 invasive groups of insects (Miller & Miller, 2003; Pellizzari & Dalla Montá, 1997; Smith et al ., 2007; Thomas, 2006). In recent decades several species of mealybug (Peudococcidae) have proved highly invasive in tropical and subtropical areas resulting in detrimental impacts to agriculture, horticulture and the environment. Examples include: pink hibiscus mealybug Maconellicoccus hirsutus (Green), which has spread from Asia to Africa and the Americas (Williams, 1986; 1996); papaya mealybug Paracoccus marginatus Williams & Granara de Willink, which has spread from the Neotropics to West Africa, Asia and the Pacific region (Muniappan et al ., 2008); bougainvillea mealybug Phenacoccus peruvianus Granara de Willink, which has spread from South America to the Mediterranean (Beltrà et al ., 2010); and solenopsis mealybug Phenacoccus solenopsis Tinsley, which has spread widely in the Neotropical Region, and to Africa, Asia and Australia (Ben- Dov, 2014; Hodgson et al ., 2008). The scale insect fauna of Ascension Island was reviewed by Ashmole & Ashmole (1997) and Williams & Mendel (2007), resulting in 19 exotic species being recorded, including three species of mealybug. Collecting by the fifth author during 2007 and second author during 2013 revealed the presence of five species of mealybug new for Ascension Island. The purpose of this communication is threefold: to provide collection details for the invasive mealybug species new to Ascension Island; to review the biology, host range, distribution and economic importance of these mealybugs; and to discuss their potential impact to the island. A revised and updated checklist of the 24 scale insects now known to occur in Ascension Island is presented in Appendix 1. METHODS A botanical survey of Ascension Island by Kew during 2007 discovered stressed and dead plants in the wild, and in cultivation at the Ascension Island Government conservation nurseries. Samples of scale insects were collected by the fifth author from endemic plants as part of this survey. Further samples of scale insects were collected during 2013 by the second author from endemic and introduced plants, as part of the Overseas Territories Environment Programme (OTEP) funded project: An Ecosystem Approach to Plant Conservation on Ascension Island. All of the samples were preserved in ethanol and submitted to The Food and Environment Research Agency (FERA), UK, where they were slide-mounted according to the procedures published by Malumphy (2002), and identified by the first author using diagnostic keys provided by Cox (1989), Granara de Willink (2003; 2009), Granara de Willink & Szumik (2007), Williams (1985; 2004), Williams & Granara de Willink (1992), and Williams & Watson (1988). Slide-mounted voucher specimens were deposited at FERA. RESULTS Ten species of scale insect were identified in the samples collected in 2007 and 2013, including five species of mealybug recorded for the first time for Ascension Island. A summary of the distribution, host range, and economic importance of the new mealybugs is provided below. Detailed information on all the species of scale insect recorded from the island can be obtained from an online catalogue ScaleNet (http://www.sel.barc.usda.gov/scalenet/scalenet.htm). 3746_Layout 1 26/02/2015 17:40 Page 3 Entomologist’s Monthly Magazine (2015) Vol. 151 0 MEALYBUGS NEW FOR ASCENSION ISLAND Antonina graminis (Maskell) – Rhodes grass mealybug Of Asiatic origin, A. graminis is a highly successful coloniser that has spread widely in the tropics and subtropics (Ben-Dov, 2014). It is parthenogenetic, ovoviviparous, and may have up to five generations a year, depending on climatic conditions. It is oligophagous on grasses (rarely on bamboo) (Poaceae), and has been recorded feeding on more than 50 grass genera (Hendricks & Kosztarab, 1999; Ben-Dov, 2014). It is a pest of pasture and turf grass and the most severe damage appears to be caused to Rhodes grass Chloris gayana . Infested plants turn brown and may die. It is an occasional pest of Bermuda grass C. dactylon , sugarcane Saccharum officinarum , Johnson grass Sorghum halepense , and St. Augustine grass Stenotaphrum secundatum . Collection data . Razor’s Edge (N: 0576065; E: 9122015): three adult females hidden at the base of the leaves of wild populations of Cyperus appendiculatus (Cyperaceae), 7.xi.2013, leg. C. Supple & L.F. White. Chorizococcus rostellum (Lobdell) – Bermuda grass mealybug Chorizococcus rostellum is suspected to be native to the Americas (Williams & Granara de Willink, 1992) and has spread to southern and Central Europe, South Africa, Australia and Hawaii. It is oligophagous on Poaceae, and occasionally found on herbaceous plants and other non-grass hosts (Ben-Dov, 2013). It is very common on numerous grass species, particularly Bermuda Grass Cynodon dactylon in the southern USA, and has been found on sugarcane in Hawaii (Beardsley, 1960), but has not been reported to be an economic pest. Collection data. Conservation Department’s Green Mountain conservation nursery: on Sporobolus caespitosus (Poaceae), 25.x.2007, leg. M. Hamilton. Dysmicoccus brevipes (Cockerell) – pineapple mealybug This species originated in tropical America (Rohrbach et al ., 1988) and has spread to all zoogeographical regions, mainly in the tropics and subtropics (CIE, 1972; Ben-Dov, 1994). It is broadly polyphagous, feeding on plants belonging to at least 63 families, with a preference for Arecaceae, Bromeliaceae, Cyperaceae, Fabaceae, Poaceae and Rubiaceae. It is a major economic pest of pineapple on which it transmits the Pineapple Mealybug Wilt Disease . Other crops affected include avocado, banana, celery, citrus, clover, cocoa, coconut, coffee, cotton, custard apple, figs, ginger, guava, maize, mango, oil palm, orchids, groundnut, peppers, pineapple, plantain, potato and sugarcane. Collection data . There were large numbers of mealybugs present in each of these samples. North East Bay Road: project site (N: 0572828; E: 9124167), on C. appendiculatus , 7.x.2013, leg. L.F. White. Razor’s Edge (N: 0576065; E: 9122015): on C. appendiculatus , 7.xi.2013, leg. C. Supple & L.F. White. White Horse Hill, Restoration Site (N: 0575843; E: 9121367): on C. appendiculatus, 12.ix.2013, leg. L.F. White. Phenacoccus solani Ferris – solanum mealybug This species is native to North America, and in recent years has spread widely throughout the tropical and subtropical