Coccus pseudomagnoliarum (Kuwana)
(Synonym: Coccus aegaeus De Lotto).
Common name: Citricola scale insect.
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Sternorrhyncha, Coccomorpha, Coccidae.
Geographical distribution: Almost cosmopolitan.
Morphology: Body elongated, 2-7 mm long, dark brown and slightly convex, with a central pale longitudinal ridge and two short transverse pale stripes extending inwards from the spiracles. Body of young crawlers almost transparent.
Host plants: Citrus, Celtis, Laurus, Nerium and Ulmus.
Life history: This parthenogenic pest is univoltine, beginning to lay eggs (about 2000/female) in spring. The emerging crawlers settle on leaves, whereon they develop till autumn, when they migrate to twigs and overwinter. They reach adulthood in spring and begin to lay eggs.
Economic importance: A major pest of citrus whose infestations can greatly reduce yields. Damage is due to sucking nutrients from the leaves and twigs and to producing much honeydew that is colonized by sootymold fungi. Tree vigor is affected as a result, twigs may die, and there are fewer flowers and smaller fruit.
Management
Monitoring: Transparent sticky tape traps can be used to monitor the appearance of crawler populations, for timing chemical sprays.
Chemical control: Due to the univoltine life cycle of the pest, chemicals (like oils mixed with an organophosphates should be applied only against the susceptible crawlers, in the spring. However, the pest has developed resistance to such chemicals.
Biological control: Several Encyrtidae, such as Coccophagus spp., especially C. lycimnia (Walker), and Metaphycus spp., especially M. helvolus (Compere) control the pest in different countries, unless their efficacy is curtailed by encapsulation. The predator Chilocorus bipustulatus and other Coccinellidae, like Rhyzobius, also feed on the pest and reduce its numbers.
References
Argyriou, L.C. and Ioanides, A.G. 1975 Coccus aegaeus (Homoptera, Coccoidea, Coccidae) De Lotto: nouvelle espèce de lecanine des Citrus en Grèce. Fruits 30: 161-162.
Blumberg, D. 1997 Parasitoid encapsulation as a defense mechanism in the Coccoidea (Homoptera) and its importance in biological control. Biological Control 8: 225-236.
Chueca, P., Grafton-Cardwell, E.E. and Moltó, E. 2009 Influence of spray equipment and water volume on coverage of citrus and control of citricola scale, Coccus pseudomagnoliarum (Hemiptera: Coccidae) with mineral oil.. Journal of Economic Entomology 102: 296-303.
Dreistadt, S.H. 1996. Citricola scale (Homoptera: Coccidae) abundance on Chinese hackberry and scale control with spray oil or acephate trunk implants. Journal of Economic Entomology 89: 481-487.
Mohamed, E.M., Basheer, A.M. and Abukaf, N. 2012. Survey of parasitoid species of citricola scale insect, Coccus pseudomagnoliarum (Kuwana) (Homoptera: Coccidae) and their effect in citrus orchards at Lattakia, Syria. Egyptian journal of pest control 22: 61-65.
Ouyang, Y., Chueca, P., Scott, S.J., Montez, G.H. and Grafton-Cardwell, E.E. 2010. Chlorpyrifos bioassay and resistance monitoring of San Joaquin Valley California citricola scale populations. Journal of Economic Entomology 103: 1400-1404.
Richards, A.M. 1981. Rhyzobius ventralis (Erichson) and R. forestieri (Mulsant) (Coleoptera: Coccinellidae), their biology and value for scale insect control. Bulletin of Entomological Research 71: 33-47.
Tena, A. and Garcia-Mari, F. 2008. 2008. Suitability of citricola scale Coccus pseudomagnoliarum (Hemiptera: Coccidae) as host of Metaphycus helvolus (Hymenoptera: Encyrtidae): Influence of host size and encapsulation. Biological Control 46: 341-347.
Websites
http://idtools.org/id/citrus/pests/factsheet.php?name=Citricola%20scale