(Cockerell, 1895)
Taxonomy
The reference to Aspidiotus curcumae Kasargode (a nomen nudum) by Kotikal and Kulkarni, 2000, probably refers to Aspidiella hartii.
Diagnosis
Scale cover of adult female in life circular, brown to brownish-grey with slightly paler, approximately central exuviae ASPHARL1.jpg ; a circular white ventral scale is produced, which shows conspicuously on the host if the dorsal scale cover is removed ASPHARL3.jpg . Scale cover of male smaller and more elongate than that of female ASHARL.jpg . Exposed body of adult female creamy white or very pale yellow. ASPHARL2.jpg and ASPHARL4.jpg
Body of slide-mounted adult female pyriform to elongate-pyriform, membranous ASHARS.jpg . Pygidial margin without any paraphyses; only two pairs of rounded lobes present; plates present on margin lateral to where third lobes would be; median lobes with basal scleroses poorly developed and parallel; pygidial margin weakly crenulate ASHARP1.jpg .
Host range
Aspidiella hartii has been recorded on hosts from the plant family Dioscoreaceae (Borchsenius, 1966) and Zingiberaceae. The species is associated with yams, especially tubers in storage, but also occurs on other root crops, especially Zingiberaceae when grown in proximity with yams (Williams and Watson, 1988). Hosts include species of: Colocasia, Curcuma longa, Dioscorea, Ipomoea batatas and Zingiber.
Affected plant stages: vegetative growing, flowering, fruiting and post-harvest stages
Affected plant parts: tubers and roots ASPHARL6.jpg ; occasionally on aerial parts of the plant also
Biology and ecology
Little is known about the biology of A. hartii (Heu, 1986); apparently reproduction is sexual. Dispersal over short distances is by first instar crawlers, which 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.
After an infested crop has been harvested or stored, it is best to avoid planting the field or re-filling the storage facility with root crops for some time, to avoid perpetuating the infestation.
Symptoms
Infestation of a crop in the field does not usually show any symptoms on the foliage or stems, as only the tubers and roots are attacked; however, stunted growth may result from heavy infestations (Chua and Wood, 1990). Infestation of stored tubers by A. hartii causes desiccation of the tissues so that they become light, fibrous and unpalatable (Cohic, 1958). The white underscales left on the rhizomes where the scales have been feeding disfigure them, making them less marketable ASPHARL5.jpg .
Economic impact
Aspidiella hartii is a common pest of yams in the old world tropics and the Pacific region (Chua and Wood, 1990); Dioscorea alata and D. esculenta are particularly badly affected (Williams and Watson, 1988). Cohic, 1958, mentioned that infestation of stored tubers by A. hartii caused desiccation of the tissues so that they become fibrous and unpalatable. The white underscales left on the rhizomes where the scales have been feeding disfigure them, reducing the value of the crop or even making it unmarketable. Aspidiella hartii is a potential field and storage pest of Zingiberaceae such as ginger and turmeric, and of other tropical root/rhizome crops that are stored before consumption, e.g. taro and dasheen. The mention of Aspidiotus curcumae as a major pest of turmeric (Curcuma longa) in India (Karnataka) by Kotikal and Kulkarni, 2000, probably refers to Aspidiella hartii.
It is recommended that planting of yam should not follow ginger or tumeric, to avoid build-up of populations in the field. Aspidiella hartii is more damaging to yam than to ginger or tumeric (Chua and Wood, 1990).
Detection and inspection methods
In good light, inspect rhizomes for circular, white underscales and brown scale covers 1.0-2.5 mm across.
Phytosanitary risk
There is a risk of introduction of A. hartii to tropical countries if infested tubers or rhizomes of tropical root/rhizome crops are imported, especially if they are used for planting purposes or are stored together with other root crops that are later used for planting.
Natural enemies
Parasitoids:
- Adelencyrtus moderatus, in India
- Coccobius comperei, in India
Distribution
See Aspidiella hartii distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Rhizaspidiotus dearnessi (Cockerell) (Dearness scale) RHIDES.jpg is a species not included in the key, which could be mistaken for A. hartii. However, R. dearnessi lacks perivulvar pores and has no plates or space between the median lobes RHIDEP.jpg; these characters are present in A. hartii ASHARP1.jpg. Rhizaspidiotus dearnessi is native to western North America, and has been recorded from Canada, Cuba, Mexico, USA (Alabama, Arizona, California, Colorado, Florida, Georgia, Indiana, Kansas, Massachusetts, Maryland, Missouri, New England, New Jersey, New Mexico, New York, North Carolina, Oklahoma, South Carolina, Texas, Utah, Virginia and Wisconsin) (Nakahara, 1982; Miller, 1996). It is polyphagous on herbaceous plants, but is usually found on the stems, crowns and even on the roots of species of Eriogonum (Polygonaceae), Vaccinium (Ericaceae) and various Compositae such as Ambrosia, Applopappus, Artemisia, Franseria, Gutierrezia and Helianthus. In life, adult female scale cover 1.5-2.5 mm in diameter, circular, fairly convex, tan or grey, with tan subcebtral or submarginal exuviae and a strongly developed ventral scale. Scale cover of male white or tan, oval, with subterminal exuviae. This species is usually well hidden except in heavy infestations (Gill, 1997). In the former USSR (the west of Belorussia), R. dearnessi is a pest of cranberries (Vaccinium oxycoccus), feeding on the overground parts of the plants, sucking the sap from all parts and causing the roots to dry up in severe infestations (Shutova et al., 1981). RHDEL1.jpg , RHIDEL.jpg See also genus Rhizaspidiotus, kingdom Animalia.
Comments
Aspidiella hartii is a tropicopolitan species (Williams and Watson, 1988) whose area of origin is not known. It has not been recorded from Europe, and has been eradicated from USA (Hawaii) (Heu, 2002).
Asia
China
Hong Kong: present, no further details (Heu, 1986)
India: present, no further details (Heu, 1986; Williams and Williams, 1988)
?Karnataka: (as Aspidiotus curcumae) (Kotikal and Kulkarni, 2000)
Kerala: present, no further details (Pillai and Rajamma, 1987)
Maharashtra: present, no further details (CIE, 1966a)
Tamil Nadu: present, no further details (CIE, 1966a)
Malaysia: present, no further details (Heu, 1986)
Philippines: present, no further details (Heu, 1986)
Sri Lanka: present, no further details (CIE, 1966a)
Thailand: The Natural History Museum collection, London, UK
Africa
Côte d'Ivoire: present, no further details (CIE, 1966a; Heu, 1986)
Ghana: present, no further details (CIE, 1966a; Heu, 1986)
Mauritius: present, no further details (Williams and Williams, 1988)
Nigeria: present, no further details (CIE, 1966a; Heu, 1986)
Sierra Leone: present, no further details (CIE, 1966a; Heu, 1986)
Zambia: present, no further details (Heu, 1986)
Western Hemisphere
Antigua: present, no further details (CIE, 1966a)
Barbados: present, no further details (CIE, 1966a; Bennett and Alam, 1985)
?Bermuda: not collected since 1949 (Hodgson and Hilburn, 1991; The Natural History Museum, London, UK)
Cayman Is: present, no further details (CIE, 1966a)
Dominican Republic: present, no further details (CIE, 1966a)
Ecuador: present, no further details (Heu, 1986)
Grenada: present, no further details (CIE, 1966a)
Guadeloupe: The Natural History Museum collection, London, UK
Honduras: present, no further details (Heu, 1986)
Jamaica: present, no further details (CIE, 1966a)
Panama: present, no further details (CIE, 1966a; Heu, 1986)
St Kitts: present, no further details (CIE, 1966a)
St Vincent: present, no further details (CIE, 1966a)
Trinidad: present, no further details (CIE, 1966a; Beardsley, 1966)
Virgin Is: present, no further details (CIE, 1966a)
Oceania
Australia: The Natural History Museum collection, London, UK
Fiji: present (Heu, 1986; Williams and Watson, 1988)
Guam: present, no further details (CIE, 1966a; Heu, 1986)
Loyalty Is: present (Cohic, 1958)
New Caledonia: present (Cohic, 1956; CIE, 1966a)
Papua New Guinea: present (Williams and Watson, 1988)
Solomon Is: present (Williams and Watson, 1988)
Tonga: present (Williams and Watson, 1988)
Vanuatu: present (Williams and Watson, 1988)
Wallis Is: present, no further details (CIE, 1966a)