(Cockerell, 1896)
Diagnosis
Scale cover of adult female in life oval or circular, convex, brown with orange-yellow submarginal or subcentral exuviae PSDUL1.jpg . Scale cover of male similar to that of female but smaller, elongate oval, brown with orange-yellow submarginal exuviae (Davidson and Miller, 1990) PSDUPL.jpg .
Body of slide-mounted adult female approximately elongate pyriform, but with a pronounced constriction between pro- and mesothorax; cuticle becoming sclerotized with maturity PSDUPS.jpg . Pygidium with dorsal areolate sclerotized area present; median lobes each only slightly longer than wide; paraphyses present, each without a detached knob at inner end; perivulvar pores present in four groups; and apex of pygidium rounded or slightly pointed PSDUP1.jpg .
Host range
Pseudaonidia duplex has been recorded from hosts belonging to 57 genera in 10 plant families (Davidson and Miller, 1990). Hosts include species of: Arbutus, Azalea, Camellia, Cinnamomum, Citrus, Diospyros kaki, Eurya, Ficus, Ligustrum, Michelia, Myrica rubra, Olea, Prunus, Pyrus, Quercus, Rhododendron, Rhus, Rosa and Vitis vinifera.
Affected plant stages: vegetative growing, flowering and fruiting stages
Affected plant parts: mainly on bark of stems and branches PSDUL2.jpg ; less often, on fruits and leaves
Biology and ecology
In northern Taiwan, peak populations were reached in late summer (Shiao, 1978); there were four generations per year, and overwintering was as fertilized females; the life-span of the female was 76-200 days and that of the male was 34-59 days; the ratio of females to males was about 2:3; and each female laid about 160 eggs. There was a negative relationship between development and temperature (Shiao, 1977).
In Japan on tea plants, P. duplex had only one generation per year (Murakami, 1970). Cressman et al., 1935, recorded 3-3.5 generations per year in Louisiana, overwintering as mated females, and a development time of 51 days from egg to egg-laying female (Cressman and Plank, 1935).
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
Pseudaonidia duplex is a serious pest of tea in northern Taiwan (Shiao, 1977), infesting the stem, branches and leaves, making the bushes weak and unproductive; persistent attacks may kill pruned bushes (Chua and Wood, 1990). In the USA, P. duplex is a pest of ornamental plantings (Kosztarab, 1996). in China (Zhejiang), Wang et al., 2000, recorded it as an important pest of Arbutus, and Wang et al., 1998, mentioned that it was an important pest of Myrica rubra.
Detection and inspection methods
Examine the bark of stems and branches of the hosts listed above, for oval or circular, convex, brown scale covers, each with orange-yellow submarginal or subcentral exuviae PSDUL1.jpg .
Natural enemies
Parasitoids:
- Anabrolepis bifasciata in Taiwan
- Aphytis sp. in Taiwan
- Neochrysocharis sp. in Taiwan
- Thompsonisca sp. in Taiwan
Predators:
- Karnyothrips flavipes
- Pharoscymnus taoi, in Taiwan
- Platoeceticus gloveri, in southern USA
Pathogens:
- Nectria auranticola, in Taiwan
Distribution
See Pseudaonidia duplex distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Comments
The area of origin of Pseudaonidia duplex was probably in the Oriental region, but the species has spread. It has not been recorded from Australia, the Pacific islands, Africa or from western Europe.
Europe
Former USSR
Abkhazia: present, no further details (Nakahara, 1982)
Transcaucasus: present, no further details (Danzig and Pellizzari, 1998)
West Gruzia: present, no further details (Nakahara, 1982)
Asia
China:
Anhui: present, no further details (Tao, 1999)
Beijing: present, no further details (Tao, 1999)
Guangdong: present, no further details (Tao, 1999)
Guangxi: present, no further details (Tao, 1999)
Guizhou: present, no further details (Tao, 1999)
Hong Kong: The Natural History Museum collection, London, UK
Hubei: present, no further details (Tao, 1999)
Hunan: present, no further details (Tao, 1999)
Jiangsu: present, no further details (Tao, 1999)
Jiangxi: present, no further details (Tao, 1999)
Sichuan: present, no further details (Tao, 1999)
Yunnan: present, no further details (Tao, 1999)
Xizang: present, no further details (Tao, 1999)
Zhejiang: present, no further details (Tao, 1999; Wang et al., 2000)
India: present, no further details (Davidson and Miller, 1990)
Assam: The Natural History Museum collection, London, UK
Japan: present, cannot read any further details (Kawai, 1980; Danzig and Pellizzari, 1998)
Honshu: present, no further details (Danzig and Pellizzari, 1998)
Korea: present, no further details (Davidson and Miller, 1990)
Sri Lanka: present, no further details (Davidson and Miller, 1990)
Taiwan: present, no further details (Wong et al., 1999)
Western Hemisphere
Argentina: present, no further details (Tao, 1999; Claps et al., 2001a)
Central America: present, no further details (Danzig and Pellizzari, 1998)
USA
Alabama: present, no further details (Nakahara, 1982)
Florida: present, no further details (Nakahara, 1982)
Georgia: present, no further details (Nakahara, 1982)
Louisiana: present, no further details (Nakahara, 1982)
Mississippi: present, no further details (Nakahara, 1982)
New Orleans: The Natural History Museum collection, London, UK
Texas: present, no further details (Nakahara, 1982)
Virginia: present, no further details (Nakahara, 1982)