Parlatoria blanchardi Targioni Tozzetti

Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Coccoidea, Diaspididae.

Common name: Parlatoria date scale, white scale.

Geographical distribution: The Mediterranean Basin, India, Iraq, Australia, south-west USA (whence it has apparently been exterminated). Commonwealth Institute of Entomology Map #148, 1962.

**Host plants: ** Date palms

**Morphology: ** The dorsal macroducts are two-barred, and the orifices of the marginal macroducts on the pygidium are surrounded by weakly sclerotized rings, not as strong as in other species of Parlatoria, and the body is oval. The Parlatoria date scale has no macroducts within the frame formed by the perivulvar pores, of which there are about 15-20 on each side; by the smooth or weakly notched external margins of the pygidial lobes, and by the hardly-discernible fourth lobe. The anus is located between the posterior groups of perivulvar pores. There are no duct tubercles on the prosoma, which dorsally bears a prominent eye spot placed nearly opposite the anterior spiracles. The body of all stages (including the winged males) and of the eggs is violet, except shortly after molting, when it is white. The female shield is pear shaped, consisting mostly

of the brownish second-stage exuvium, which has a

paler, caudal appendage, secreted by the female. The dorsal exuvium of the

first stage is lighter, placed at one end of the female’s shield, from which

it slightly protrudes. The shield of the male is whitish, elongated, bearing

at one end the pale exuvium of the crawler.

** Life cycle: ** The optimal conditions for the reproduction of this scale are around 24°C and relative humidity of ca 55%, being limited below 15°C and 30% RH. In Egypt and southern Israel the pest has two annual generations, in spring and autumn, whereas in the inner valleys of Israel three complete generations are annually raised. Oviposition continues throughout the year, resulting in considerable overlapping of generations.

**Economic importance: ** The scale infests the rachis, pinnae and fruits of date palms. Feeding on the pinnae causes their yellowing and subsequent tree stunting. Scales disfigure the fruit they settle on, reducing the economic value.

Management

**Chemical control: ** Applications of organophosphates along with white oil may control the pest, but many scales survive such treatments due to being hidden in the axils of pinnae and beneath the dry fibers.

Biological control: In the Middle East

Parlatoria date scale is controlled by a large guild of predators, of which

the most important are ladybeetles (Coleoptera:

Coccinellidae). These include several species of _

Pharoscymnus_ as well as [ _Chilocorus

bipustulatus_](ChilocorusBipustulatus) (L.) and _ Rhyzobius_. Other major

predators include several species of _ Cybocephalus_

(Coleoptera: Cybocephalidae). The

hymenopterous

ectoparasitoid aphelinid

Aphytis phoenicis DeBach and Rosen is a major

parasitoid of the pest. These natural enemies, unless disrupted by pesticides,

mainaitain P. blanchardi** **below its economic injury level.

References

Belkhiri, D., Mehaoua, M.S. and Biche, M. 2011. Study of fecundity of Parlatoria blanchardi of the date palm and essay of chemical control in a palmeraie in Biskra. Acta Horticulturae 994: 379-383.

Blumberg, D. 2008. Date palm arthropod pests and their management in Israel. Phytoparasitica 36: 411-448.

Idder-Ighili, H., Idder, M.A., Doumandji-Mitiche, B. and Chenchouni, H. 2015. Modeling the effects of climate on date palm scale (Parlatoria blanchardi) population dynamics during different phenological stages of life history under hot arid conditions. International Journal of Biometeorology, in press.

Kehat, M. 1967. Some notes on the life cycle of the date palm scale, _

Parlatoria blanchardi_ Targ., in Israel. _ Israel Journal of Agricultural

Research_ **17: ** 175-179.

Matallah, S. and Biche, M. 2011. Biological behavior of Parlatoria blanchardi Targioni 1892 (Homoptera: Diaspididae) towards three cultivars of date palm tree in the region of Biskra, Algeria. Acta Horticulturae 994: 389-394.

Salama, H.S. 1972. On the population density and bionomics of _ Parlatoria

blanchardi_ (Targ.) and _ Mycetaspis personatus_ (Comstock) (Homoptera -

Coccoidea). _ Zeitschrift fur angewandte Entomologie_ **70: ** 403-407.

Websites: http://wbd.etibioinformatics.nl/bis/diaspididae.php?menuentry=soorten&id=154