Diversinervus elegans Silvestri
Taxonomic placing: Insecta, Holometabola, Hymenoptera, Apocrita, Chalcidoidea, Encyrtidae.
Distribution: Cosmopolitan. Apparently of central African origin.
Hosts: Various Coccidae and Aphidoidea.
Morphology: Female about 1.3 mm in length, yellow and brown, venter and antennae mostly brown, legs whitish. Male mostly dark, shiny blue, legs whitish, about 1.4 mm in length. The antennae of females and males bear dense hairs.
Life history: An endoparasitoid of several Coccidae, especially of Saissetia oleae. The preovipositing host females (known as the “rubber stage”) and its ovipositing females are the preferred host stages. Its other hosts enables D. elegans to be active almost the year around, being most abundant in spring, with a smaller peak in autumn. Reproduction is by arrhenotoky, and several eggs may be placed in each host. The pupae of D. elegans may sometimes remain in the host for long periods before adult emergence, an adaptation that can carry the parasitoid over periods of host scarcity.Diversinervus elegans can be mass-reared on Coccus hesperidum.
Economic importance: Diversinervus elegans is a major enemy of S. oleae in olive groves as well as citrus orchards; but its activities may be disrupted by pesticides. The endoparasitoid was shipped from Israel to Crete and reduced S. oleae populations by about 30%.
References
Abd-Rabou, S. 1999. Parasitoids attacking the Mediterranean black scale, Saissetia oleae (Hemiptera: Coccidae) on olive in Egypt. Entomologica, Bari 33: 169-172.
Bartlett, B.R. and Medved, R.A. 1966. The biology and effectiveness of Diversinervus elegans (Encyrtidae: Hymenoptera), an imported parasite of Lecaniine scale insects in California. Annals of the Entomological Society of America 59: 974-976.
Paraskakis. M., Neuenschwander, P. and Michelakis, S. 1980. Saissetia oleae (Oliv.) (Hom., Coccidae) and its parasites on olive trees in Crete, Greece. Zeitung fur agewandte Entomologie 90: 450-464.
Rosen, D. 1967. The hymenopterous parasites of soft scales on citrus in Israel. Beiträge zur Entomologie 17: 251-279.
Rosen, D., Harpaz, I. and Samish, M. 1971. The species of Saissetia (Homoptera: Coccidae) injurious to olive in Israel and their natural enemies. Israel Journal of Entomology 6: 35-53.
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