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DICTYOSPERMUM SCALE, Chrysomphalus dictyospermi (Morgan) -- Diaspididae

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This is a polyphagous species which is widely distributed in subtropical regions and is the most serious insect pest of citrus in the western Mediterranean (Quayle 1938). It is also of major importance in Greece and Iran, but only a minor problem in California, Florida, Mexico and South America (Kennett et al. 1999).

Dictyospermum scale is known as Spanish red scale in Greece, where it is considered more serious on citrus than either the California red scale or the purple scale. Although such parasitoids as Aphytis chrysomphali and other native species have been considered ineffective, there were no attempts to introduce additional parasitoids prior to 1962 (DeBach & Argyriou 1967). Aphytis lingnanensis, A. melinus and A. coheni were imported via California during 1962-63 for control of both dictyospermum and California red scales. Aphytis melinus became established on both scale species by 1963 (DeBach & Argyriou 1967, <PHOTO>), while A. lingnanensis and A. coheni did not persist after some initial recoveries. Aphytis melinus displaced A. chrysomphali at all original release sites within two years. The effective rate of dispersal for A. melinus was 75-100 km per year (DeBach & Argyriou 1967). DeBach (1974) reported by 1968 only an occasional specimen of C. dictyospermi could be found on previously heavily scale-infested trees at original release sites.

Biological control of dictyospermum scale was begun in Italy in 1908 and in Corsica in 1923 (Greathead 1976). However complete control was obtained only after the establishment of A. melinus in Italy in 1964 and Corsica in 1972 (Greathead 1976, Benassy 1977, Rosen & DeBach 1978). Complete control was obtained with A. melinus in Morocco following establishment of A. melinus in 1966 (Benassy & Euverte 1970). Turkey benefitted from natural dispersal of this parasitoid out of Greece (Tuncyureck & Oncuer 1974). This particular success is apparently an example of a parasitoid controlling a host on which it did not evolve (DeBach 1974).

Please refer to the following references for greater detail on biologies and biological control work of dictyospermum scale (Berlese & Paoli 1916, Paoli 1922a,b; Cressman 1933, Smirnoff 1952, Flanders 1953, Ebeling 1959, DeBach 1962, Inserra 1966)

REFERENCES: [Additional references may be found at: MELVYL Library]

Benassy, C. 1977. Notes on parasites of some diaspine scale insects (Chrysomphalus, Lepidosaphes, Unaspis). Bull. Serv. Defen. Plagas e Insp. Fitopatologica 3: 55-73.

Benassy, C. & G. Euverte. 1970. Note on the action of two species of Aphytis as biological control agents against two citrus coccids, Aonidiella aurantii Mask. and Chrysomphalus dictyospermi (Morg.) in Morocco. Ann. Zool. Ecol. Anim. 2: 357-72.

Berlese, A. 1916. Un endofago esotico efficace contro il Chrysomphalus dictyospermi Morg. Redia 11: 305-07.

Cressman, A. W. 1933. Biology and control of Chrysomphalus dictyospermi (Morg.). J. Econ. Ent. 26: 696-706.

DeBach, P. 1962. Species of Aphytis for possible use in the biological control of Chrysomphalus dictyospermi. Food & Agric. Organ. Plant Protect. Bull. 10. p. 29.

DeBach, P. 1974. Biological Control by Natural Enemies. Cambridge Univ. Press, London, New York. 323 p.

DeBach, P. & L. C. Argyriou. 1967. The colonization and success in Greece of some imported Aphytis spp. (Hym.: Aphelinidae) parasitic on citrus scale insects (Hom.: Diaspididae). Entomophaga 12: 325-42.

Ebeling, W. 1959. Subtropical Fruit Pests. Calif. Univ. Div. Agric. Sci. Pub. 436 p.

Flanders, S. E. 1953. Hymenopteraous parasites of three species of Oriental scale insects. Portici R. Scuola Super. di Agric. Lab. Zool. Gen. e Agric. Bol. 33: 10-28.

Greathead, D. J. 1976. A review of biological control in western and southern Europe. Tech. Comm. No. 7, CIBC. Commonw. Agr. Bur., Farnham Royal, Slough, England. 182 p.

Inserra, S. 1966. Introduzione ed acclimatazione di due Aphytis (A. melinus DeBach ed A. lingnanensis Compere) parassiti ectofagi di alcune cocciniglie degli agrumi. Technica Agric. (Italy) 2. 11 p.

Kennett, C. E., J. A. McMurtry & J. W. Beardsley. 1999. Biological control in subtropical and tropical crops. In: Bellows, T. S. & T. W. Fisher (eds.), Handbook of Biological Control: Principles and Applications. Academic Press, San Diego, New York. 1046 p

Paoli, G. 1922a. Il parassita della bianca-rossa degli agrumi e la sua introduzione in Italia. Il Coltivatore, Casale Monferrato 15. 7 p. [in Italian].

Paoli, G. 1922b. La moltiplicazione dell'endofago della bianca-rossa in Italia. Il Coltivatore 33. [in Italian].

Quayle, H. J. 1938. Insects of Citrus and Other Subtropical Fruits. Comstock Publishing Co., Ithaca, N. Y. 583 p.

Rosen, D. & P. DeBach. 1978. Diaspididae. In: C. P. Clausen (ed.), Introduced Parasites and Predators of Arthropod Pests and Weeds. U.S.D.A. Agric. Handbk. No. 480, Washington, D.C. 545 p.

Smirnoff, W. A. 1952. Aspidiotiphagus lounsburyi Berl. et Paoli (Chalcidoidea, Aphelinidae) parasite de certaines especes de Diaspidoidae (Homopt.) au Maroc. REv. Pathol. Veg. 31: 63-9.

Tuncyreck, M. & C. Oncuer. 1974. Studies on aphelinid parasites and their hosts, citrus diaspine insects, in citrus orchards in the Aegean region. Bull. SROP.OILB 3: 95-108.