(Cockerell, 1899)
Diagnosis
Scale cover of adult female in life usually embedded under epidermis of host; oval or circular, convex, brown with orange-yellow submarginal or subcentral exuviae PSPAEL1.jpg and PSPAEOL.jpg . Scale cover of male similar to that of female but smaller, elongate oval, brown with orange-yellow submarginal exuviae (Davidson and Miller, 1990) PSPAEOL.jpg . Exposed body of adult female purplish; adult male alate, with a purplish body (Stoetzel, 1975).
Body of slide-mounted adult female approximately elongate pyriform, but with a pronounced constriction between pro- and mesothorax, and some degree of development of lateral lobes on other thoracic segments; cuticle remaining membranous at maturity PSPAEOS.jpg . Pygidium with dorsal areolate sclerotized area present; paraphyses present, each without a detached knob at inner end; and perivulvar pores present in two groups PSPAEOP1.jpg .
The first and second instar nymphs of both sexes of P. peaoniae were described and illustrated by Tippins et al., 1981.
Host range
Pseudaonidia paeoniae has been recorded from hosts belonging to 15 genera in four plant families (Davidson and Miller, 1990). Hosts include species of: Azalea, Camellia, Ilex, Paeonia and Rhododendron.
Affected plant stages: vegetative growing, flowering and fruiting stages
Affected plant parts: on bark of stems and branches PSPAEL1.jpg , often under bark flakes
Biology and ecology
In Japan on tea plants, P. paeoniae had only one generation per year (Murakami, 1970); also in Georgia (Tippins et al., 1977); southern USA (Westcott, 1973); Alabama (English and Turnipseed, 1940); Maryland (McComb and Davidson, 1969) and the former USSR (Tikhonov, 1966; Kunincka, 1970). Under glass in the USA, Stoetzel, 1975, recorded continuous reproduction all year round; each adult female produced a batch of 30-50 eggs, followed by 2-4 per day until death. Overwintering probably occurs as adult females; adult males are winged (Kosztarab, 1996).
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
Heavy infestations can kill twigs and branches (Johnson and Lyon, 1991).
Economic impact
Pseudaonidia paeoniae is an important pest of azaleas, camellias and other ornamental plants in USA (Georgia) (Tippins et al., 1981).
Detection and inspection methods
Closely examine stems and branches of the host-plants listed above, especially under bark flakes, for oval or circular, convex, brown scale covers, usually embedded under the epidermis of the host PSPAEL1.jpg .
Phytosanitary risk
Pseudaonidia paeoniae is mentioned on quarantine lists (Burger and Ulenberg, 1990).
Natural enemies
The natural enemies of P. paeoniae have not been studied.
Distribution
See Pseudaonidia paeoniae distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Comments
The area of origin of Pseudaonidia paeoniae was probably in the Oriental region, but the species has spread. It has not been recorded from Australia, the Pacific islands, Africa, Central or South America, or from most of western Europe.
Europe
Former USSR
Georgia, Republic of: present, no further details (Nakahara, 1982)
Transcaucasus: present, no further details (Danzig and Pellizzari, 1998)
Italy: present, no further details (Longo et al., 1995; Danzig and Pellizzari, 1998)
Asia
China: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Jiangxi: present, no further details (Tao, 1999)
Yunnan: present, no further details (Tao, 1999)
Japan: present, no further details (Nakahara, 1982; Danzig and Pellizzari, 1998)
Western Hemisphere
USA
Alabama: present, no further details (Nakahara, 1982)
Arkansas: present, no further details (Nakahara, 1982)
District of Colombia: present, no further details (Nakahara, 1982)
Delaware: 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)
Maryland: present, no further details (Nakahara, 1982)
Missouri: present, no further details (Nakahara, 1982)
Mississippi: present, no further details (Nakahara, 1982)
North Carolina: present, no further details (Nakahara, 1982)
New Jersey: present, no further details (Nakahara, 1982)
New York: present, no further details (Nakahara, 1982)
Pennsylvania: present, no further details (Nakahara, 1982)
South Carolina: present, no further details (Nakahara, 1982)
Texas: present, no further details (Nakahara, 1982)
Virginia: present, no further details (Nakahara, 1982)