Chlidaspis asiatica

(Archangelskaya, 1930)

Taxonomic note
The morphology of Chlidaspis asiatica varies in response to different substrates; the species occurs in leaf and twig forms. The leaf form was originally described as a separate species, Phenacaspis prunorum, but is now recognized as a ecophenotypic variant of C. asiatica (Danzig, 1993; Takagi and Verma, 2001). The taxonomic position of this species is not well settled (Takagi and Verma, 2001).

Scale cover of adult female in life broadly pear-shaped, 1.25-1.4 mm long, sometimes slightly curved, pure white with orange terminal exuviae (Balachowsky, 1954; Danzig, 1993). Exposed body of adult female orange (Danzig, 1993). Scale cover of male narrow, 0.75-1.25 mm long, white, with three faint longitudinal ridges (Archangelskaya, 1937).

Body of slide-mounted adult female oval, membranous; pygidium with zygotic median lobes, with a pair of marginal setae (but no gland spines) situated between them CHLASS.jpg . Pygidial segment VI bearing several gland spines on either side CHLASP.jpg . Orifices of dorsal ducts more or less circular; orifices of marginal macroducts with the long axes of their orifices not all clearly perpendicular, or parallel to, margin of pygidium, but variable.

In the leaf form of C. asiatica, the median lobes form a distinct notch at the apex of the pygidium, the second lobes have well-developed and sclerostized lobules, and the third lobes are represented as small processes CHLASMGL.jpg . In the twig form, the apical notch between the median lobes is slight; the development of the second lobes varies and they are often reduced or absent; and the third lobes are minute or absent CHLASMGT.jpg . Details of the variation are discussed by Takagi and Verma, 2001.

Host range
Chlidaspis asiatica has been recorded from hosts belonging to two plant families: Rosaceae and Vitaceae (Borchsenius, 1966). Rosaceae are favoured hosts, especially pip fruit; nut trees and vines are also attacked (Balachowsky, 1954). Hosts include species of: Cydonia, Malus spp., Prunus spp., Pyrus spp. and Vitis vinifera.

Affected plant stages: vegetative growing, flowering and fruiting stages

Affected plant parts: on bark of branches and twigs all year; in summer, spreads to leaves (both surfaces) and sometimes fruits

Biology and ecology
In the former USSR, C. asiatica has two generations per year and overwinters as adult females on the bark (Danzig, 1993). The data provided by Bustshik, 1960, with only single dates for larval emergence, male flight and female oviposition, suggested there was only one generation per year in Turkmenistan.

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.

Economic impact
Danzig and Pellizzari, 1998, describe C. asiatica as a dangerous pest in the Palaearctic region. It was mentioned as a dangerous pest of stone fruits in Central Asia by Kozár, 1990b, and Balachowsky, 1954, and Danzig, 1993, say it was damaging to plum, apricot and almond. Takagi and Verma, 2001, said that C. asiatica is not a serious pest on apple or plum in India (Himachal Pradesh), due to the action of natural enemies.

Detection and inspection methods
Examine the bark of the hosts listed above, for broadly pear-shaped, sometimes slightly curved, pure white scale covers, each with orange terminal exuviae.

Natural enemies
Takagi and Verma, 2001, mention that populations of C. asiatica appear to be regulated by some parasitic natural enemy in India (Himachal Pradesh). Some natural enemies of C. asiatica are listed by Herting and Simmonds, 1972.

- Aphytis proclia
- Chermis mayri
- Coccobius testaceus
- Coccophagoides similis
- Polynema sp.
- Pteroptrix lauri

See Chlidaspis asiatica distribution.

Microscopic examination of slide-mounted adult females is required for authoritative identification to species.

Chlidaspis asiatica probably originated in Central Asia, and has not spread very far beyond its original range. It has not been recorded from western Europe, Africa, the Western Hemisphere, Australia, or from the Pacific islands.

Former USSR
Armenia: present, no further details (Danzig, 1993; Danzig and Pellizzari, 1998)
Russia: present, no further details (Archangelskaya, 1937)
Transcaucasus: present, no further details (Danzig and Pellizzari, 1998)
Tadjikistan: present, no further details (Danzig and Pellizzari, 1998)
Turkmenistan: present, no further details (Bustshik, 1960; Danzig, 1993)
Tadjikistan: present, no further details (Danzig, 1993)
Uzbekistan: present, no further details (Danzig, 1993; Danzig and Pellizzari, 1998)

Afghanistan: present, no further details (Takagi and Verma, 2001)
Himachal Pradesh: present (Takagi and Verma, 2001)
Iran: present (Seghatoleslami, 1977; Danzig and Pellizzari, 1998)
Turkey: present, no further details (Erler et al., 1996)