Diadegma semiclausum

Diadegma semiclausum Hellén

(Also known as Diadegma cerophagus (Gravenhorst).

Systematic position: Insecta, Holometaboa, Hymenoptera, Apocryta, Chalcidoidea, Ichneumonidae.

Geographic distribution: The probable origin of this species is Africa, but it has been introduced into many regions and is now almost cosmopolitan.

Morphology: Females are shiny black, with yellow legs and very long antennae, about 3-4 mm in length.

Life history: Diadegma semiclausum is a parasitoid of the diamond-back moth, Plutella xylostella. A life cycle is completed in 12-16 days, from egg laying (up to 700/female) in the host (usually a young larva) to adult emergence. If honey and nectar are available, adults can live up to 25 days, but without food survival is only 3 days. It is a strong flier. Although usually more abundant in cooler regions, a strain from Syria showed some heat tolerance, which could be used to introduce D. semiclausum into warmer regions for pest control.

Economic importance: Diadegma semiclausum is a major natural enemy of P. xylostella. It has been introduced, and had become established in various regions, even when only 150-300 adults were released. The parasitoid has attacked and killed as many as 70%, or more, of pest populations in many parts of the world. It has the ability to move 15-30 km from release sites, and in Eastern Africa it displaced indigenous parasitoids of P. xylostella.

Effect of pesticides: Carbamates and pyrethroids are very toxic to D. semiclausum, but inhibitors of Chitin synthetase had little effect.


Abbas, M.S.T. 1988. Biological and ecological studies on Diadegma semiclausum Hellen (Hym., Ichneumonidae), a larval parasite of the diamond-back moth, Plutella xylostella (L.) (Lep., Plutellidae) in Egypt. Anzeiger für Schädlingskunde, Pflanzenschutz, Umweltschutz 61: 1–2

Gichini, G., Lohr, B., Rossbach, A., Nyambo, B. and Gathu, R. 2008. Can low release numbers lead to establishment and spread of an exotic parasitoid: the case of the diamondback moth parasitoid, Diadegma semiclausum (Hellen), in East Africa. Crop Protection 27: 906–914.

Haseeb, M., Amano, H. and Nemoto, H. 2000. Pesticidal effects on mortality and parasitism rates of Diadegma semiclausum, a parasitoid of the diamondback moth. BioControl 45: 165-178.

Juric, I., Salzburger, W. and O. Balmer, O. 2017. Spread and global population structure of the diamondback moth Plutella xylostella (Lepidoptera: Plutellidae) and its larval parasitoids Diadegma semiclausum and Diadegma fenestrale (Hymenoptera: Ichneumonidae) based on mtDNA. Bulletin of Entomological Research 107: 155-164.

Kadirvel, P., Srinivasan, R., Lin, M.-y., Al-Jouri E., Walid, I.M. and de la Peña, R.C. 2011. Occurrence of Diadegma semiclausum, a parasitoid of diamondback moth in lowlands of Syria. Journal of Asia-Pacific Entomology 14 52–57.

Löhr, B., Gathu, R., Kariuki, C., Obiero, J. and Gichini, G. 2007. Impact of an exotic parasitoid on Plutella xylostella (Lepidoptera: Plutellidae) population dynamics, damage and indigenous natural enemies in Kenya. Bulletin of Entomological Research 97: 337-50.

Sarfraz , M., Keddie, A.B. and Dosdall L.M. 2005. Biological control of the diamondback moth, Plutella xylostella: a review. Biocontrol Science and Technology 15: 763–789.