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CITRICOLA SCALE, Coccus pseudomagnoliarum (Kuwana) -- Coccidae

Following its discovery in southern California in 1907, citricola scale became an important pest of citrus (Quayle 1938). It was then found in Japan and Arizona. Since 1951 it has been found in the Soviet Union (1951), Iran (1963), Greece (1972), Turkey (1971), Italy (1976), Sicily (1973) and Australia (1978) (Kennett et al. 1999).

As of 1991 the only attempts at biological control of citricola scale were made in California. Although unsuccessful in every area except southern California, the results are considered significant because of the complete lack of progress (Flanders & Bartlett 1964, Kennett et al. 1999). During 1922-1985 six species of monophagous and oligophagous parasitoids were introduced from Japan but failed to establish (Gressitt et al. 1953). Citricola scale was eventually controlled in southern California by a complex of parasitoids, including native, cosmopolitan and exotic species, the latter being introduced against the black scale, Saissetia oleae (Bartlett 1953). Under the greater climatic extremes of central and northern California, the same species of parasitoids were ineffective in controlling citricola scale on citrus, and it continues to remain a pest. (Kennett et al. 1999).

A general failure to establish parasitoids imported from Japan, in particular the host-specific Metaphycus orientalis (Compere) and Microterys okitsuensis Compere, is attributed to an inability to bridge the summer period, at which time the univoltine, even-brooded host scales are too small for parasitoids to reproduce (Compere 1924, Flanders & Bartlett 1964, Kennett 1988, Kennett et al. 1999). Parasitoids that have moved over to citricola scale after it invaded other countries recently, suggests that biological control might be possible in the more extreme climatic conditions of central California (Oncuer 1974, Kennett 1988, Kennett et al. 1999) (also see Gressitt et al. 1954, Bartlett 1960, Annecke 1963, Bartlett & Ball 1964, Saakian-Baranova 1965, 1966; and Yasumatsu & Watanabe 1965).

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

Annecke, D. P. 1963. The encyrtid and aphelinid parasites (Hymenoptera: Chalcidoidea) of soft brown scale, Coccus hesperidum Linnaeus (Hemiptera: Coccidae) in South Africa. South Africa Dept. Agric. Tech. Serv., Ent. Mem. 7. 75 p.

Bartlett, B. R. 1953. Natural control of citricola scale in California. J. Econ. Ent. 46: 25-8.

Bartlett, B. R. 1960. Biological races of the black scale, Saissetia oleae, and their specific parasites. Ann. Ent. Soc. Amer. 53: 383-85.

Bartlett, B. R. & J. C. Ball. 1964. The developmental biologies of two encyrtid parasites of Coccus hesperidum and their intrinsic competition. Ann. Ent. Soc. Amer. 57: 496-503.

Compere, H. 1924. A preliminary report on the parasitic enemies of the citricola scale [Coccus pseudomagnoliarum (Kuwana)] with descriptions of two new chalcidoid parasites. Bull. So. Calif. Acad. Sci. 24: 113-23.

Flanders, S. E. & B. R. Bartlett. 1964. Observations on two species of Metaphycus (Encyrtidae, Hymenoptera) parasitic on citricola scale. Mushi 38: 39-42.

Gressitt, J. L. 1953. The coconut rhinoceros beetle (Oryctes rhinoceros) with particular reference to the Palau Islands. Bul. 212, B. P. Bishop Museum, Honolulu. 157 p.

Gressitt, J. L., S. E. Flanders & B. Bartlett. 1954. Parasites of citricola scale in Japan, and their introduction into California. Pan-Pacific Ent. 30: 5-9.

Kennett, C. E. 1988. Results of exploration for parasitoids of citricola scale Coccus pseudomagnoliarum (Homoptera: Coccidae), in Japan and their introduction in California. Kontyu 56: 445-57.

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

Oncuer, C. 1974. The Coccus species (Homoptera: Coccidae) damaging citrus groves in the Aegean region; studies on their morphological characters, distribution and natural enemies. Bitki Koruma Balteni, Suppl. 1. 51 p.

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

Saakian-Baranova, A. A. 1965. On the host-parasite relations between Coccus hesperidum L. (Homoptera, Coccidae) and some Encyrtidae. Trudy Zool. Inst. Akad. Nauk., USSR 45: 733-52. [in Russian w/ English summary].

Yasumatsu, K. & C. Watanabe. 1965. A tentative catalogue of insect natural enemies of injurious insects in Japan. Pt. II. Host-parasite-predator catalogue. Kyushu Univ. Faculty Agric., Ent. Lab. 116 p