(Newman, 1869)
Diagnosis
In life, scale cover of adult female 1.0-3.0 mm long, convex, mussel-shaped (curved or straight, depending on the texture of the host and population density of the scales), strongly tapered towards the exuvial end, dark brown (occasionally with light tan edges and a purplish tinge) with yellowish-brown exuviae at the narrow end LEBEL5.jpg and LEBEL2.jpg . Second instar exuviae of the female with a distinctive reddish-brown spot at the posterior end, like L. gloverii. Male scale cover similar to female cover but smaller, straighter and narrower LEBEL6.jpg and LEPBEL.jpg . Body of adult female translucent white (Davidson and Miller, 1990; Gill, 1997).
Body of slide-mounted adult female elongate, more than 1.8x as long as wide, and membranous, with a rounded head; head without obvious lateral tubercles; eye not developed into a spur; a dorsal double boss present on the prothorax on a level with the anterior spiracle; and with lateral marginal spurs absent from margins of prepygidial segments LEPBES.jpg . Pygidium with median lobes with a pair of gland spines between them; not yoked, and without any club-shaped basal scleroses; perivulvar pores present; with 6 marginal macroducts on each side of pygidium; sclerotized dorsal bosses present on abdominal segments I, II, IV and V LEPBEP.jpg .
Host range
Lepidosaphes beckii is a polyphagous species that has been recorded from hosts belonging to 45 genera in 11 plant families (Davidson and Miller, 1990) but its host range may well be wider. Citrus species are favoured hosts, and Murraya exotica is often heavily infested (Williams and Watson, 1988). Hosts include species of: Agave sisalana, Banksia, Cercidiphyllum, Citrus spp., Croton, Cupressus, Elaeagnus, Ficus, Hibiscus, Ilex, Mangifera indica, Murraya exotica, Musa, Myrtus, Orchidaceae, Persea, Pinus, Piper, Pomaderris, Poncirus, Prunus, Pyrus, Quercus, Raphia, Rosa, Taxus, Theobroma, Vitis and Wigandia.
Affected plant stages: vegetative growing, flowering, fruiting and post-harvest stages
Affected plant parts: aerial parts of the plant - leaves LEBEL4.jpg , bark and fruit LEBEL3.jpg and LEBEL1.jpg
Biology and ecology
Reproduction in L. beckii can be either sexual or parthenogenetic. Each female lays 40-80 eggs, which hatch about 8 days later. The threshold development temperature is 8°C and 1104 day-degrees are required for the completion of one generation. Development time varies considerably with temperature (e.g. in females, development varies from 20 days at 27°C to 40 days at 20°C (Hafez and Salama, 1970)). Up to four generations may be produced each year, depending on climatic conditions. In California, there are 3-4 overlapping generations per year, and all stages are present through the winter (Gill, 1997); in colder climates, overwintering may occur in the egg stage. In southern Chile there is one generation annually (Zuniga, 1971), and two in France (Bénassy et al., 1975); generation counts for several other countries are provided by Davidson and Miller, 1990.
Cohic, 1955, mentioned that L. beckii prefers hot humid conditions and is found in the shady inner part of the canopy of Citrus until overcrowding makes it spread onto the leaves and fruit. Infestations are usually heaviest at the centre of trees and on northern aspects. In California, L. beckii populations are particularly prevalent in coastal areas, which may reflect its low tolerance of extreme temperatures (Gill, 1997). Bénassy et al., 1980, noted that young orange trees were not attacked by L. beckii.
The first instar crawler is responsible for dispersal by crawling, and by being passively carried between hosts by wind or animal agencies. Crawlers can survive for up to 3 days without feeding. Mortality due to abiotic factors is high in this stage. Crawlers often settle underneath the calyx (leaf-like covering of the flower) or on the upper half of the fruit. Dispersal of sessile adults and eggs can also occur through human transport of infested plant material.
Further information is provided by Hafez and Salama, 1970; Beardsley and Gonzalez, 1975; Debach and Rosen, 1991; and Dreistadt, 1994.
Symptoms
On Citrus, heavy infestation causes chlorosis of the leaves LEBEL4.jpg , defoliation, discolouration and poor maturation of the fruit; and desiccation, weakening and dieback of the branches or even entire trees (Cohic, 1955; Gill, 1997). Damage to fruit occurs in heavy infestations, where spotting and often deformity of fruits affects market value. Areas surrounding scales on fruit remain green long after the rest of the fruit ripens. The areas surrounding the scale insects on leaves turn yellow and when severely infested the entire leaf may be discoloured prematurely and be shed.
Economic impact
Lepidosaphes beckii is one of the most important pests of Citrus wherever it is grown (Williams and Watson, 1988), more important than Aonidiella aurantii (Gill, 1997). Nymphs and adults suck sap from the foliage and branches, weakening the branches and reducing productivity. On the fruits, infestation causes disfiguration and poor maturation, which decreases their market value and can make them unmarketable (Cohic, 1955). Lepidosaphes beckii is regarded as a serious pest in Argentina (Claps et al., 2001a). Danzig and Pellizzari, 1998, described it as a dangerous pest in the Palaearctic, and Foldi, 2001, lists it as an economically important pest in France.
Phytosanitary risk
Dispersal of scale insects is predominantly though infected planting stock, thus imported host-plant material for planting or propogation should be thoroughly checked for the presence of scales.
Detection and inspection methods
Examine plant material in good light; purplish brown scale covers may be present on bark, stems, leaves and fruit, especially in shaded parts of the canopy. Infestations are usually heaviest at the centre of trees and on northern aspects. Densities of scales may be greater on the midribs of leaves and in pits in the rinds of fruits. Heavy infestations may go unnoticed owing to the cryptic colour of the scales.
Phytosanitary protection
Lepidosaphes beckii is mentioned on quarantine lists (Burger and Ulenberg, 1990).
Natural enemies
Parasitoids:
- Aphytis columbi, attacking: nymphs, in Australia
- Aphytis chrysomphali, attacking: nymphs in Australia
- Aphytis holoxanthus , attacking: nymphs, in Australia
- Aphytis lepidosaphes, ectoparasite attacking: eggs, nymphs, adults, in China, Taiwan. Introduced: USA, Central and South America, southern Europe, Egypt, South Africa, Australia, New Caledonia, Hawaii, California
- Aphytis lingnanensis, attacking: nymphs, in China, Taiwan and Japan. Introduced: USA (California), South Africa, Australia, Mexico, Argentina, Chile, Cyprus, Israel, Morocco
- Encarsia citrina, attacking: nymphs, in Japan. Introduced to: USA; Australia; Mediterranean Basin; Turkey; Italy, Indonesia (Bali), Tahiti, Fiji, Cook Islands, Africa
- Signiphora fax
Predators:
- Aleurodothrips fasciapennis, attacking: eggs, nymphs, adults, in Indonesia; introduced to: Fiji
- Chilocorus spp., attacking: nymphs, adults
- Chilocorus nigrita, attacking: nymphs, adults, in India and South-East Asia, introduced to Africa, Oman
- Chrysopa sp., in Brazil (Sao Paulo)
- Haplothrips callani, in South Africa
- Haplothrips merrilli, in Cuba, USA (Florida), Puerto Rico
- Hemisarcoptes spp., attacking: nymphs, adults, in Canada, California, West and South Africa and the Middle East; introduced to British Columbia, Bermuda and New Zealand
- Hemisarcoptes malus, attacking: nymphs, adults
- Karnyothrips flavipes
- Pentilia egena, in Brazil (Sao Paulo)
- Rhyzobius pulchellus, attacking: nymphs, adults, in Vanuatu, New Caledonia
Distribution
See Lepidosaphes beckii distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species. In life, L. beckii can be distinguished from L. gloverii by having a shorter, broader scale cover. Lepidosaphes beckii can be distinguished from species of Unaspis in life by the colour of the male scale covers, which are brown in L. beckii and white and carinated in Unaspis species (Gill, 1997).
Comments
Gill, 1997, suggested that Lepidosaphes beckii might originate from the Oriental region. It is widely distributed now, throughout the tropical and subtropical regions of the world (Davidson and Miller, 1990; DeBach and Rosen, 1991). In northern countries it is found only under glass (Danzig and Pellizzari, 1998). In spite of the record published by Danzig and Pellizzari, 1998, L. beckii is not established in the United Kingdom (C.P. Malumphy, Central Science Laboratory, UK, pers. comm.).
Europe
Cyprus: present, no further details (CIE, 1982)
Former USSR
Azerbaijan: present, no further details (CIE, 1982)
Georgia, Republic of: present, no further details (CIE, 1982)
Russian Federation: present, no further details (CIE, 1982)
Transcaucasus: present, no further details (Danzig and Pellizzari, 1998)
Former Yugoslavia: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
France: present, no further details (Foldi, 2001)
Corsica: present, no further details (CIE, 1982; Bénassy et al., 1980)
Germany: present, no further details (Danzig and Pellizzari, 1998)
Greece: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Crete: present, no further details (CIE, 1982)
Italy: present in the south (Longo et al., 1995; Danzig and Pellizzari, 1998)
Sardinia: present, no further details (Longo et al., 1995)
Sicily: present, no further details (Longo et al., 1995)
Malta: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Portugal: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Madeira: present, no further details (Danzig and Pellizzari, 1998)
Romania: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Spain: widespread (CIE, 1982; Amparo Blay Golcoechea, 1993)
Canary Is: present, no further details (Amparo Blay Golcoechea, 1993)
Asia
Bhutan: The Natural History Museum collection, London, UK
Brunei Darussalam: The Natural History Museum collection, London, UK
Cambodia: present, no further details (CIE, 1982)
China
Fujian: present, no further details (CIE, 1982; Tao, 1999)
Guangdong: present, no further details (CIE, 1982; Tao, 1999)
Guangxi: present, no further details (Tao, 1999)
Hong Kong: present, no further details (DeBach and Rosen, 1991; Tao, 1999)
Hubei: present, no further details (CIE, 1982)
Jiangsu: present, no further details (Tao, 1999)
Zhejiang: present, no further details (Tao, 1999)
India
Assam: present, not further details (CIE, 1982)
Karnataka: present, not further details (CIE, 1982)
Kerala: present, not further details (CIE, 1982)
Manipur: present, not further details (CIE, 1982)
Sikkim: present, not further details (CIE, 1982)
Tamil Nadu: present, not further details (CIE, 1982)
Uttar Pradesh: The Natural History Museum collection, London, UK
Indonesia
Irian Jaya: present, no further details (Maddison, 1976)
Java: present, not further details (CIE, 1982)
Sumatra: present, not further details (CIE, 1982)
Iran: present, no further details (Seghatoleslami, 1977; Abivardi, 2001)
Iraq: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Israel: present, no further details (DeBach and Rosen, 1991)
Japan: present (CIE, 1982; Kawai, 1980)
Honshu: present, no further details (CIE, 1982)
Kyushu: present, no further details (CIE, 1982)
Laos: present, no further details (CIE, 1982)
Lebanon: present, no further details (CIE, 1982)
Malaysia: present, no further details (CIE, 1982; Waterhouse, 1993)
West Malaysia: present, not further details (CIE, 1982)
Sabah: The Natural History Museum collection, London, UK
Maldive Is: present, no further details (Watson et al., 1995)
Myanmar: present, not further details (CIE, 1982)
Nepal: The Natural History Museum collection, London, UK
Pakistan: The Natural History Museum collection, London, UK
Philippines: present, no further details (CIE, 1982)
Singapore: present, no further details (CIE, 1982)
Sri Lanka: present, no further details (CIE, 1982)
Syria: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Taiwan: present, no further details (Wong et al., 1999; Tao, 1999)
Thailand: The Natural History Museum collection, London, UK
Turkey: present, no further details (CIE, 1982)
Vietnam: present, no further details (CIE, 1982)
Africa
Ascension Is: The Natural History Museum collection, London, UK
Algeria: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Angola: present, no further details (CIE, 1982)
Benin: present, not further details (CIE, 1982)
Burundi: present, no further details (CIE, 1982)
Cameroon: present, no further details (CIE, 1982)
Cape Verde Is: present, no further details (CIE, 1982)
Congo Democratic Republic: present, no further details (CIE, 1982)
Côte d'Ivoire: present, not further details (CIE, 1982)
Egypt: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Ethiopia: present, no further details (CIE, 1982)
Gambia: present, no further details (CIE, 1982)
Ghana: present, no further details (CIE, 1982)
Guinea: present, no further details (CIE, 1982)
Kenya: present, no further details (CIE, 1982)
Libya: present, no further details (CIE, 1982)
Madagascar: present, not further details (CIE, 1982)
Malawi: present, no further details (CIE, 1982)
Mauritius: present, no further details (CIE, 1982; Williams and Williams, 1988)
Morocco: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Mozambique: present, no further details (CIE, 1982)
Nigeria: present, no further details (CIE, 1982)
Principe: The Natural History Museum collection, London, UK
Réunion: present, no further details (Williams and Williams, 1988)
Rodrigues: present, no further details (Williams and Williams, 1988)
Rwanda: present, no further details (CIE, 1982)
Sao Tomé: present, no further details (CIE, 1982)
Senegal: present, no further details (CIE, 1982)
Seychelles: present, no further details (CIE, 1982)
Sierra Leone: present, no further details (CIE, 1982)
Somalia: present, no further details (CIE, 1982)
South Africa: present, no further details (CIE, 1982)
St Helena: present, no further details (CIE, 1982)
Swaziland: The Natural History Museum collection, London, UK
Tanzania: present, no further details (CIE, 1982; Bohlen, 1973)
Zanzibar: The Natural History Museum collection, London, UK
Tunisia: present, no further details (CIE, 1982; Danzig and Pellizzari, 1998)
Uganda: present, no further details (CIE, 1982)
Upper Volta: present, not further details (CIE, 1982)
Zimbabwe: present, no further details (CIE, 1982)
Western Hemisphere
Argentina: widespread (Claps et al., 2001a)
Buenos Aires: present, not further details (CIE, 1982)
Mendoza: present, not further details (CIE, 1982)
Paraná Delta: present, not further details (CIE, 1982)
Bahamas: The Natural History Museum collection, London, UK
Barbados: present, no further details (Bennett and Alam, 1985)
Belize: present, no further details (CIE, 1982)
Bermuda: uncommon (Hodgson and Hilburn, 1991)
Bolivia: present, no further details (CIE, 1982)
Brazil: widespread (Silva et al., 1968; Claps et al., 2001a)
Bahia: present, not further details (CIE, 1982)
Cerrados: present, no further details (Murakami et al., 1984)
Paraná: The Natural History Museum collection, London, UK
Sao Paulo: present, no further details (Watanabe et al., 2000a)
Cayman Is: The Natural History Museum collection, London, UK
Chile
Antofagasta: present, no further details (Claps et al., 2001a)
Atacama: present, no further details (Claps et al., 2001a)
Biobío: present, no further details (Claps et al., 2001a)
Coquimbo: present, no further details (Claps et al., 2001a)
Easter Island: present, no further details (Charlín, 1973; Claps et al., 2001a)
La Araucanía: present, no further details (Claps et al., 2001a)
Maule: present, no further details (Claps et al., 2001a)
O'Higgins: present, no further details (Claps et al., 2001a)
Santiago: present, no further details (Claps et al., 2001a)
Tarapacá: present, no further details (Claps et al., 2001a)
Valparaiso: present, no further details (Claps et al., 2001a)
Colombia: present, no further details (CIE, 1982; Kondo, 2001)
Costa Rica: present, no further details (CIE, 1982)
Cuba: present, not further details (CIE, 1982)
Dominica: present, not further details (CIE, 1982)
Dominican Republic: present, not further details (CIE, 1982)
Ecuador: present, no further details (CIE, 1982)
El Salvador: present, no further details (CIE, 1982; DeBach and Rosen, 1991)
French Guiana: present, not further details (CIE, 1982)
Grenada: present, not further details (CIE, 1982)
Guadeloupe: present, no further details (DeBach and Rosen, 1991)
Guatemala: present, not further details (CIE, 1982)
Guyana: present, no further details (CIE, 1982)
Haiti: The Natural History Museum collection, London, UK
Honduras: present, no further details (CIE, 1982)
Jamaica: present, no further details (DeBach and Rosen, 1991)
Martinique: present, not further details (CIE, 1982)
Mexico: present (DeBach and Rosen, 1991; Miller, 1996)
Montserrat: present, not further details (CIE, 1982)
Nicaragua: present, no further details (CIE, 1982)
Panama: present, no further details (CIE, 1982)
Paraguay: present, no further details (CIE, 1982)
Peru: present, no further details (CIE, 1982)
Puerto Rico: present, no further details (DeBach and Rosen, 1991)
St Kitts and Nevis: present, not further details (CIE, 1982)
St Lucia: present, not further details (CIE, 1982)
St Vincent: present, not further details (CIE, 1982)
Suriname: present, no further details (CIE, 1982)
Trinidad: present, not further details (CIE, 1982)
Uruguay: present, no further details (CIE, 1982)
USA
Alabama: present, no further details (Nakahara, 1982)
California: restricted distribution in southern coastal parts and Sacramento (Gill, 1997)
Georgia: present, no further details (Nakahara, 1982)
Hawaii: present on Oahu, Hawaii, Maui, Kauai and Molokai (Heu, 2002)
Florida: present, no further details (Nakahara, 1982; DeBach and Rosen, 1991)
Kansas: under glass (Nakahara, 1982)
Louisiana: present, no further details (Nakahara, 1982)
Mississippi: present, no further details (Nakahara, 1982)
Missouri: under glass (Nakahara, 1982)
New York: under glass (Nakahara, 1982)
North Carolina: under glass (Nakahara, 1982)
Oklahoma: under glass (Nakahara, 1982)
Pennsylvania: under glass (Nakahara, 1982)
Tennessee: under glass (Nakahara, 1982)
Texas: present, no further details (Nakahara, 1982; DeBach and Rosen, 1991)
Venezuela: present, no further details (CIE, 1982)
Virgin Is: present, not further details (CIE, 1982)
Oceania
Australia
New South Wales: present, no further details (CIE, 1982; CSIRO, 2001)
Northern Territory: present, no further details (CIE, 1982; CSIRO, 2001)
Queensland: present, no further details (CIE, 1982; CSIRO, 2001)
South Australia: present, no further details (CSIRO, 2001)
Tasmania: present, not further details (CIE, 1982)
Victoria: present, no further details (CSIRO, 2001)
Western Australia: present, no further details (CSIRO, 2001)
Caroline Is: The Natural History Museum collection, London, UK
Cook Is: present (Williams and Watson, 1988)
Fiji: present (Williams and Watson, 1988)
French Polynesia: present, no further details (Reboul, 1976)
Kiribati: present (Williams and Watson, 1988)
Marquesas Is: present, no further details (Borchsenius, 1966)
Marshall Is: present (Beardsley, 1966)
New Caledonia: present (Williams and Watson, 1988)
New Zealand: present, no further details (Charles and Henderson, submitted)
Niue: present, no further details (Williams and Watson, 1988)
Norfolk I.: present, no further details (Williams and Watson, 1988)
Papua New Guinea: present (Williams and Watson, 1988)
Pohnpei: present (Beardsley, 1966)
Samoa: present, no further details (Williams and Watson, 1988)
Solomon Is: present (Williams and Watson, 1988)
South Mariana Is: present (Beardsley, 1966)
Tonga: present (Williams and Watson, 1988)
Truk Is: present (Beardsley, 1966)
Tuamotu Is: present, no further details (Borchsenius, 1966)
Vanuatu: present (Williams and Watson, 1988)
Wallis Is: present, no further details (Cohic, 1959; CIE, 1982)
Western Samoa: present (Williams and Watson, 1988)