(Bouché, 1833)
Diagnosis
In life, scale cover of adult female 1.5-2.5 mm diameter, circular and slightly convex, whitish to tan with brown subcentral exuviae DIAECHL6.jpg . Male scale cover white, elongate oval with three weak longitudinal ridges and yellow terminal exuviae (Davidson and Miller, 1990) DIAECHL2.jpg . Body of adult female greenish-yellow in life (Gill, 1997).
Body of slide-mounted adult female less than twice as long as wide, body widest at prothorax or head; without any lateral tubercles on prosoma DIAECHS.jpg . Pygidium with median lobes not zygotic, set well apart, not inset to form an obvious apical notch, with a pair of setae between their bases; bases of marginal segmental setae on pygidium not obviously enlarged and sclerotized; submedian macroducts present on pygidium DIAECHP2.jpg .
The first instar female and first and second instar male nymphs were described by Howell, 1975, and Howell and Tippins, 1977.
Host range
Diaspis echinocacti has been recorded from smooth surfaces of cacti and succulent hosts (Borchsenius, 1966); Davidson and Miller, 1990, recorded hosts belonging to 57 genera of cacti in two plant families. Hosts include species of: Astrophytum, Boehmeria, Cactaceae, Carnegiea, Cassia, Cereus spp., Chuquiraga, Corryocactus, Echinocactus, Epiphyllum, Harrisia, Hatiora, Hylocereus, Mammillaria, Melocactus, Opuntia spp., Opuntia cochonillifera, Pachycereus, Portulaca, Pterocactus, Schlumbergera, Trichocereus spp. and Zygophyllum.
Affected plant stages: vegetative growing, flowering, fruiting and post-harvest stages
Affected plant parts: all aerial parts of the plant (pads DIAECHL4.jpg , stems and fruit)
Biology and ecology
According to Oetting, 1984, D. echinocacti reproduces sexually and has multiple, overlapping generations each year. Each female lays about 150 eggs (276 is the maximum recorded) and lives for up to 230 days. Development from egg to adult takes about 23 days for females (24 for males) at 27°C and a generation is about 50 days long (Gill, 1997).
Crawlers are the primary dispersal stage and move to new areas of the plant or are dispersed by wind or animal contact. Mortality due to abiotic factors is high in this stage. Dispersal of sessile adults and eggs occurs through human transport of infested plant material.
Diaspis echinocacti is often used as a substitute host for rearing hymenopterous parasitoids in the laboratory. The species has 2n-16 chromosomes; it is thought to be probably tetraploid, based on the total length of its chromosome complement (Nur, 1990).
Symptoms
Diaspis echinocacti can cause entire cactus pads or even whole plants to wither and die (Davidson and Miller, 1990). Feeding by the diaspidid resulted in the development of chlorotic areas on the fruits of Opuntia in Sicily (Russo and Siscaro, 1994).
Economic impact
Diaspis echinocacti can be a particularly serious pest of susceptible hosts in greenhouses, sometimes causing entire cactus pads or even whole plants to wither and die (Davidson and Miller, 1990). It was reported as a pest of Opuntia sp. in French Polynesia by Reboul, 1976. In Argentina, this species can cause desiccation of host-plants growing at high altitudes (Claps et al., 2001a). Danzig and Pellizzari, 1998, describe D. echinocacti as a pest in the Palaearctic region. Foldi, 2001, lists this species as an occasional pest in France. It is a pest of 'forage palm' (Opuntia cochonillifera) in Brazil (Almeida, 1986; Lima and Barbosa, 1988). Gill, 1997, mentions that control treatments are occasionally required on cactus nursery stock in California and elsewhere against D. echinocacti. The species has recently become a pest of Opuntia in Sicily (Russo and Siscaro, 1994).
Detection and inspection methods
Examine all the aerial parts of the cactus (pads, stems and fruit) for circular, slightly convex, whitish to tan scale covers with brown subcentral exuviae. There may be associated signs of wilting or desiccation.
Natural enemies
Parasitoids:
- Aphytis spp.
- Aphytis mytilaspidis, in Greece
- Plagiomerus diaspidis, in USA (California), Mexico, Sicily
- Zaomma cestus, in South Africa
Predators:
- Aleurodothrips fasciapennis, attacking: eggs, nymphs, adults, in Indonesia; introduced to: Fiji
- Calloeneis sp., in Brazil (Alagoas)
- Coccidophilus citricola, in Argentina
- Curinus sp., in Brazil
- Exothorhis echinocactii, in Australia (Queensland)
- Pentilia egena, in Brazil (Alagoas)
- Saniosulus nudus, in Australia (Queensland)
Distribution
See Diaspis echinocacti distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Diaspis echinocacti DIAECHP2.jpg could be confused with Hemiberlesia cyanophylli HEMCYAP.jpg in the field, but the species are very different when examined as slide mounts.
Comments
Diaspis echinocacti is probably native to the New World (Gill, 1997), but it has spread wherever cacti are grown. In northern countries the species is found under glass (Danzig and Pellizzari, 1998). It has not been recorded from most of the Pacific islands.
Europe
Former USSR (under glass)
Georgia, Republic of: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Turkmenistan: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
France: present, no further details (Foldi, 2001; Danzig and Pellizzari, 1998)
Germany: present, no further details (Danzig and Pellizzari, 1998)
Gibraltar: The Natural History Museum collection, London, UK
Italy: 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 (Danzig and Pellizzari, 1998)
Mediterranean region: outdoors or under glass (Nakahara, 1982)
Portugal
Azores: present, no further details (Nakahara, 1982)
Madeira Is: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Spain: present in Alicante, Almería, Madrid, Murcia and Valencia (Amparo Blay Golcoechea, 1993)
Balearic Is: present (Amparo Blay Golcoechea, 1993)
Canary Is: present, no further details (Amparo Blay Golcoechea, 1993)
United Kingdom: restricted to a few botanical collections, under glass (C.P. Malumphy, Central Science Laboratory, UK, pers. comm.)
England: The Natural History Museum collection, London, UK
Asia
China
Guangdong: present, no further details (Tao, 1999)
Hong Kong: The Natural History Museum collection, London, UK
Inner Mongolia: present, no further details (Tao, 1999)
Jiangsu: present, no further details (Tao, 1999)
Yunnan: present, no further details (Tao, 1999)
Xizang: present, no further details (Tao, 1999)
India: present, no further details (Nakahara, 1982)
Kerala: The Natural History Museum collection, London, UK
Maharashtra: The Natural History Museum collection, London, UK
Orissa: The Natural History Museum collection, London, UK
Tamil Nadu: The Natural History Museum collection, London, UK
Iraq: present, no further details (Danzig and Pellizzari, 1998)
Israel: present, no further details (Danzig and Pellizzari, 1998)
Japan: present, no further details (Kawai, 1980; Tao, 1999)
Réunion: present, no further details (Nakahara, 1982)
Iran: present, no further details (Nakahara, 1982)
Iraq: present, no further details (Nakahara, 1982)
Israel: present, no further details (Nakahara, 1982)
Japan: present, no further details (Nakahara, 1982)
Korea: present, no further details (Danzig and Pellizzari, 1998)
Pakistan: present, no further details (Nakahara, 1982)
Philippines: present, no further details (Nakahara, 1982)
Syria: present, no further details (Nakahara, 1982)
Turkey: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Africa
Algeria: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Ascension Is: The Natural History Museum collection, London, UK
Cameroon: present, no further details (Nakahara, 1982)
Cape Verde Is: The Natural History Museum collection, London, UK
Egypt: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Guinea: present, no further details (Nakahara, 1982)
Madagascar: present, no further details (Nakahara, 1982)
Mauritius: present, no further details (Williams and Williams, 1988)
Morocco: present, no further details (Nakahara, 1982)
Mozambique: present, no further details (Nakahara, 1982)e
Réunion: present, no further details (Williams and Williams, 1988)
Senegal: present, no further details (Nakahara, 1982)
South Africa: present, no further details (Nakahara, 1982)
St Helena: present, no further details (Nakahara, 1982)
Tunisia: The Natural History Museum collection, London, UK
Western Hemisphere
Argentina
Buenos Aires: present, no further details (Claps et al., 2001a)
Catamarca: present, no further details (Claps et al., 2001a)
Córdoba: present, no further details (Claps et al., 2001a)
Formosa: The Natural History Museum collection, London, UK
Jujuy: present, no further details (Claps et al., 2001a)
Mendoz: present, no further details (Claps et al., 2001a)a
La Rioja: present, no further details (Claps et al., 2001a)
Salta: present, no further details (Claps et al., 2001a)
San Juan: present, no further details (Claps et al., 2001a)
Santiago del Estero: present, no further details (Claps et al., 2001a)
Tucumán: present, no further details (Claps et al., 2001a)
Barbados: present, no further details (Bennett and Alam, 1985)
Brazil
Alagoas: present, no further details (Almeida, 1986)
Bahia: present, no further details (Claps et al., 2001a)
Paraná: present, no further details (Claps et al., 2001a)
Pernambuco: present, no further details (Lima and Gama, 2001)
Rio de Janeiro: present, no further details (Claps et al., 2001a)
Rio Grande do Sul: present, no further details (Claps et al., 2001a)
Sao Paulo: present, no further details (Claps et al., 2001a)
Central America: present, no further details (Danzig and Pellizzari, 1998)
Chile
Atacama: present, no further details (Claps et al., 2001a)
Coquimbo: 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)
Valparaiso: present, no further details (Claps et al., 2001a)
Curaçao: The Natural History Museum collection, London, UK
Guyana: The Natural History Museum collection, London, UK
Haiti: The Natural History Museum collection, London, UK
Jamaica: The Natural History Museum collection, London, UK
Mexico: widespread (Miller, 1996; Coronado Branco et al., 1998)
New World: widely distributed (Nakahara, 1982)
North America: present, no further details (Danzig and Pellizzari, 1998)
Peru: The Natural History Museum collection, London, UK
Trinidad: The Natural History Museum collection, London, UK
Uruguay: The Natural History Museum collection, London, UK
USA: reported from most states (Nakahara, 1982)
California: widespread (Gill, 1997)
Hawaii: present, no further details (Nakahara, 1981)
Texas: The Natural History Museum collection, London, UK
Oceania
Australia: present, no further details (CSIRO, 2001)
Queensland: present, no further details (Gerson, 1994)
Papua New Guinea: present (Williams and Watson, 1988)