(Cockerell, 1893)
Diagnosis
Scale cover of adult female in life elongate mussel-shaped, 1.75-2.5 mm long, straight or curved, whitish to dark brown, with slightly darker terminal exuviae. Scale cover of male similar to that of female but smaller (1.0-1.25 mm long) and narrower, with terminal exuviae (Ferris, 1941; Dekle, 1976).
Body of slide-mounted adult female membranous except for pygidium, elongate AONAS.jpg . Pygidium with several pairs of lobes; median lobes not zygotic, well separated, with a pair of gland spines between their bases but without any basal scleroses; perivulvar pores absent; at least some gland spines occurring in groups of 2 or 3; pygidium with 6 or 7 enlarged marginal macroducts on each side; and dorsal macroducts scattered, not arranged in rows AONAP.jpg .
Host range
Aonidomytilus albus has been recorded on species of: Atriplex, Carica papaya, Chrysanthemum, Flourensia, Harrisia, Malvaceae, Malvastrum, Mangifera indica, Manihot esculenta, Manihot spp., Mimosa, Sechium, Solanum, Suaeda and Ziziphus.
Affected plant stages: vegetative growing, flowering, fruiting and post-harvest stages
Affected plant parts: lower stems and ventral surfaces of leaves
Biology and ecology
Reproduction is bisexual. Eggs hatch in 3-4 days; in 20-25 days the immature stages are full grown (Lal and Pillai, 1981). 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.
Symptoms
On cassava, A. albus coats the stems, side shoots and even sometimes the leaf petioles with scales. Heavy infestation causes dessication of the stems, causing them to become thin and weak, and break in the wind; death of the plant may result. Breakage of stems leads to profuse branching, and infested plants often appear bushy. The severity of attack becomes worse in drought conditions, aggravating drought stress. Crowded planting encourages development and spread of infestations; wide spacing of plants, and use of clean planting material, reduces the risk of serious infestation. Infested cuttings often do not root. Root development in infested plants is poor, and the roots become unpalatable (Lal and Pillai, 1981).
Economic impact
Aonidomytilus albus is a serious pest of cassava in East and West Africa, Argentina, Brazil, India, Madagascar, Mexico, Taiwan, Thailand, West Indies and USA (Florida) (Simmonds, 1960; Anon, 1978; Lal and Pillai, 1981; Wongkobrat, 1988). In Brazil, this species is a pest on Manihot and Solanum spp. (Foldi, 1988). It can cause serious damage locally in Kenya (Bruijn and Guthrie, 1982). Severe attacks on cassava cuttings kept for planting can lead to losses (Lal and Pillai, 1981; Chua and Wood, 1990); it is not so often a field pest (Lal and Pillai, 1981).
Detection and inspection methods
Look for bushy growth of cassava in the field. In the field or in the cuttings store, examine stems of cassava closely for pale to dark brown, mussel-shaped scale covers.
Natural enemies
Parasitoids:
- Signiphora fax
Distribution
See Aonidomytilus albus distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Comments
Aonidomytilus albus is a tropical species of New World origin. It has not been recorded from Australia, or from the Pacific islands.
Asia
China
Hainan: present, no further details (Tao, 1999)
India: present, no further details (Williams and Williams, 1988)
Andhra Pradesh: The Natural History Museum collection, London, UK
Karnataka: The Natural History Museum collection, London, UK
Tamil Nadu: present, no further details (CIE, 1978a)
Indonesia: present, no further details (Nakahara, 1982)
Sri Lanka: present, no further details (Williams and Williams, 1988)
Taiwan: present, no further details (Williams and Williams, 1988; Tao, 1999)
Thailand: present, no further details (Wongkobrat, 1988)
Africa
Angola: present, no further details (CIE, 1978a; Nakahara, 1982)
Cape Verde Is: The Natural History Museum collection, London, UK
Congo Democratic Republic: present, no further details (Nakahara, 1982)
Côte d'Ivoire: present, no further details (CIE, 1978a; Nakahara, 1982)
Gambia: present, no further details (Nakahara, 1982)
Ghana: present, no further details (CIE, 1978a; Nakahara, 1982)
Guinea Bissau: The Natural History Museum collection, London, UK
Kenya: present, no further details (Bruijn and Guthrie, 1982; Nakahara, 1982)
Liberia: present, no further details (Nakahara, 1982)
Madagascar: present, no further details (CIE, 1978a; Nakahara, 1982)
Malawi: present, no further details (CIE, 1978a; Nakahara, 1982)
Mauritius: present, no further details (Williams and Williams, 1988)
Mozambique: present, no further details (CIE, 1978a; Nakahara, 1982)
Nigeria: present, no further details (CIE, 1978a; Nakahara, 1982)
Senegal: present, no further details (CIE, 1978a; Nakahara, 1982)
Tanzania: present, no further details (CIE, 1978a; Nakahara, 1982)
Uganda: present, no further details (CIE, 1978a; Nakahara, 1982)
Zambia: The Natural History Museum collection, London, UK
Western Hemisphere
Argentina: present, no further details (CIE, 1978a; Nakahara, 1982)
Catamarca: very common, mainly on native plants (Claps et al., 2001a)
Jujuy: very common, mainly on native plants (Claps et al., 2001a)
Mendoza: very common, mainly on native plants (Claps et al., 2001a)
Salta: very common, mainly on native plants (Claps et al., 2001a)
San Juan: present, no further details (CIE, 1978a)
Santiago del Estero: very common, mainly on native plants (Claps et al., 2001a)
Tucumán: very common, mainly on native plants (Claps et al., 2001a)
Bahamas: present, no further details (CIE, 1978a; Nakahara, 1982)
Barbados: present, no further details (CIE, 1978a; Bennett and Alam, 1985)
Belize: present, no further details (CIE, 1978a)
Brazil: present, no further details (Nakahara, 1982; Kondo, 2001)
Amazonia: present, no further details (Claps et al., 2001a)
Bahia: present, no further details (Silva et al., 1968; Claps et al., 2001a)
Ceará: present, no further details (Bastos et al., 1979)
Paraíba: present, no further details (Silva et al., 1968; Claps et al., 2001a)
Rio Grande do Sul: present, no further details (Silva et al., 1968; Claps et al., 2001a)
Colombia: present, no further details (Lozano et al., 1977; Kondo, 2001)
Cuba: present, no further details (CIE, 1978a)
Dominican Republic: present, no further details (CIE, 1978a)
French Guiana: The Natural History Museum collection, London, UK
Guyana: The Natural History Museum collection, London, UK
Haiti: present, no further details (CIE, 1978a)
Honduras: present, no further details (Nakahara, 1982)
Jamaica: present, no further details (CIE, 1978a; Kondo, 2001)
Mexico: present, no further details (Miller, 1996; Kondo, 2001)
Peru: present, no further details (Nakahara, 1982)
St Vincent: present, no further details (CIE, 1978a)
Suriname: present, no further details (CIE, 1978a; Nakahara, 1982)
USA: present, no further details (Williams and Williams, 1988)
Florida: present, no further details (Nakahara, 1982; Miller, 1996)
New Mexico: present, no further details (CIE, 1978a)