(Coleman, 1903)
Diagnosis
In life, female scale cover oblong or elongate, moderately convex, 2.0-2.5 mm diameter, consisting of a very large, central blue-black or grey-black second-instar exuviae with a white or light grey rim of scale material; central first-instar exuviae chestnut brown if visible DYNCAL1.jpg . Male scale cover similar to that of the female but more oblong, with subcentral to subterminal exuviae DYNCALL.jpg . Body of living female yellow when young, becoming brown and sclerotized with age (Gill, 1997).
Body of adult female pyriform, about 0.9 mm long; prosoma without any constrictions, becoming expanded and heavily sclerotized with maturity; abdominal segments III and IV each with a group of about 9 submarginal ducts on either side DYNCALO.jpg . Anus smaller than a median lobe, situated more than 2.4x its diameter from base of median lobes. Pygidium tending to retract into prosoma in mature specimens; with three pairs of rounded lobes, paraphyses absent or, if present, shorter than the lobes and quite slender. Plates and perivulvar pores present. Fourth lobes represented by sclerotized points or patches; margin lateral to fourth lobes smooth, without paraphyses, often somewhat sclerotized DYNCALP.jpg .
Host range
Dynaspidiotus californicus has been recorded from hosts belonging to the coniferous plant family Pinaceae (Borchsenius, 1966), especially species of Pinus (Gill, 1997). Hosts include species of: Pinus, Pseudotsuga and Tsuga.
Affected plant stages: vegetative growing, flowering and fruiting stages
Affected plant parts: on the needles only DYNCAL3.jpg
Biology and ecology
Gill, 1997, records 1-3 generations per year in California, and overwintering as second instars. In northern USA there is one generation per year (Kosztarab, 1996). Edmunds, 1973, records D. californicus as probably viviparous or ovoviviparous, each female producing about 40 eggs; dispersal is by wind movement of the first instar crawlers; overwintering is as immature instars; and males are winged. The sex ratio in D. californicus has been found to be strongly biased in favour of females (Nur, 1990).
Symptoms
Dynaspidiotus californicus causes severe chlorosis and reddish discolouration of the needles DYNCAL2.jpg , defoliation and stunted growth, and young trees may be killed outright; defoliation makes the trees prone to sunburn, and the general debilitation makes the trees prone to bark beetle attack (Edmunds, 1973; Gill, 1997).
Economic impact
This species is a serious pest of pines on the west coast of the USA, especially on ponderosa and other yellow pines (McKenzie, 1956; Gill, 1997). Death of trees sometimes occurs (Johnson and Lyon, 1991).
Detection and inspection methods
Inspect needles of the hosts listed above, for oblong or elongate, moderately convex scale covers consisting of very large, central blue-black or grey-black exuviae with a white or light grey rim of scale material DYNCAL3.jpg
DYNCAL2.jpg .
Natural enemies
Parasitoids:
- Encarsia sp., in USA
Predators:
- Chilocorus sp., in USA
- Microweisia sp., in USA
Distribution
See Dynaspidiotus californicus distribution.
Microscopic examination of slide-mounted adult females is required for authoritative identification to species.
Comments
Dynaspidiotus californicus is apparently native to North America (Gill, 1997); it has not been recorded outside this land mass.
Western Hemisphere
Canada: present, no further details (Miller, 1996)
British Colombia: present, no further details (Wood and Ross, 1972)
Mexico: widespread in the north (Miller, 1996; Gill, 1997)
USA: widepread in most of the continental USA (Miller, 1996; Gill, 1997)
California: widespread (Gill, 1997)