Metaphycus
Taxonomic placing: Insecta, Holometabola, Hymenoptera, Apocryta, Chalcidoidea, Encyrtidae.
Common name: None.
Geographical distribution: Wherever the hosts, usually soft scales (Coccidae), occur.
Hosts: Mostly soft scales, but also members of other Coccoidea, including the Diaspididae.
Morphology: Both males and females are about 1-1.5 mm in length, with mostly yellow bodies. The eyes are greenish and some antennal and leg segments are black. The larva is yellow.
Life history: The over 250 species of Metaphycus are endoparasitoids of soft scales and a few other Coccoidea. Males locate females by their pheromones. Single eggs are laid in small hosts, more (up to a dozen or more) in large scales (Metaphycus lounsburyi (Howard) may lay up to 40 eggs in a female of Saissetia oleae). The sex-ratio is affected by host size, as larger hosts lead to more endoparasitoid female offspring. When several eggs are deposited in the same host (“super parasitism”), physical conflict may occur, resulting in the death of the smaller larvae. Another factor that affects the developing larvae is encapsulation. For instance, when Metaphycus helvolus (Compere) attacks adults of Coccus hesperidum, all parasite larvae die. Rates of encapsulation in some hosts are low during winter, high in summer. Most species of Metaphycus complete a generation in 2-3 weeks, females deposit about 35-50 eggs and may live for several weeks. Host feeding prolongs adult lives, increases theor fecundity and kills the host-scales
Economic importance: Several species of Metaphycus control or greatly reduce the numbers of several pestiferous soft scales in the Middle East. These pests and their endoparasitoids include:
Ceroplastes floridensis: Metaphycus flavus Howard.
Ceroplastes cirripediformis: M. flavus.
Coccus hesperidum: M. flavus, Metaphycus helvolus, Metaphycus lounsburyi, Metaphycus luteolus (Timberlake), Metaphycus stanleyi Compere and Metaphycus swirskii Annecke and Mynhardt.
Milviscutulus mangiferae: M. flavus.
Parasaissetia nigra: M. stanleyi.
Protopulvinaria pyriformis: M. helvolus, M. stanleyi, M. swirskii.
Saissetia coffeae: M. flavus, M. helvolus, M. lounsburyi, M. stanleyi, Metaphycus zebratus Mercet and M. swirskii.
Saissetia oleae: M. flavus, M. helvolus M. lounsburyi, and M. zebratus and the diaspidid
Acanthomytilus sacchari: Metaphycus flavus and Metaphycus swirskii.
At times the controlling effect of these natural enemies is diminished by ants and by encapsulation by some hosts. Several of these Metaphycus spp. are in world-wide commerce and have successfully been introduced into various regions and became established there.
References
Abd-Rabou, S. The role of augmentative releases of indigenous parasitoid Metaphycus lounsburyi (Hymenoptera: encyrtidae) in enhancing the biological control of Saissetia oleae (Homoptera: coccidae) on olive in Egypt. Archives of Phytopathology and Plant Protection 37: 233-237.
Avidov, Z. and Podoler, H. 1970. Studies on the life history of Metaphycus flavus (How.) (Encyrtidae). Israel Journal of Entomology 3: 1-16.
Bernal, J.S., Luck, R.F. and. Morse, J.G. 1999. Host influences on sex ratio, longevity, and egg load of two Metaphycus species parasitic on soft scales: implications for insectary rearing. Entomologia Experimentalis et Applicata 92:191–204.
Blumberg, D. 1997. Parasitoid encapsulation as a defense mechanism in the Coccoidea (Homoptera) and its importance in biological control. Biological Control 8: 225–236.
Daane, K.M. and Caltagirone, L.E. 1989. Biological control of black scale in olives. California Agriculture 9: 1-3.
Kapranas, A., Lo Giudice, D., Peri, E., .Millar, J.G. and Colazza, S. 2013. Emergence, dispersal, and mate finding via a substrate-borne sex pheromone in the parasitoid Metaphycus luteolus. Entoimologia Experimentalis et Applicata 148: 74-83.
Prinsloo, G.L. 1997. Encyrtidae. Pages 69-109 in Ben-Dov, Y. and Hodgson, C.J. (Eds) Soft Scale Insects, Their Biology, Natural Enemies and Control. Vol. 7B. Elsevier Science H.V. Amsterdam.
Tena, A., Kapranas, A., Garcia-Mari, F. and Luck, R.F. 2009. Larval cannibalism during the late developmental stages of a facultatively gregarious encyrtid endoparasitoid. Ecological Entomology 34: 669–676.
Tena, A. and Garcia-Mari, F. 2009. Brood size, sex ratio and egg load of Metaphycus lounsburyi (Hymenoptera: Encyrtidae) when parasitizing adult females of black scale Saissetia oleae (Hemiptera: Coccidae) in the field. Biological Control 51: 110–115.
Watson, G.W. and El-Serwy, S.A. 2008. Aspects of the biology, ecology and parasitism of Acanthomytilus sacchari (Hall) (Hemiptera: Diaspididae) on sugarcane in Egypt. Proceedings of the XI International Symposium on Scale Insect Studies, pp. 322