Diadromus collaris (Gravenhorst, 1829)

Rousse, Pascal, van Noort, Simon & Diller, E., 2013, Revision of the Afrotropical Phaeogenini (Ichneumonidae, Ichneumoninae), with description of a new genus and twelve new species, ZooKeys 354, pp. 1-85 : 28-31

Diadromus collaris (Gravenhorst, 1829) Figs 11-12

Diadromus cabrerai Berthoumieu, 1903; Diadromus punicus Berthoumieu, 1898; Diadromus rufiscapus Pic, 1902; Heterischnus hispanicus Berthoumieu, 1904; Ischnus collaris Gravenhorst, 1829; Ischnopsidea brevicauda Hellén, 1949; Phaeogenes bellulus Kriechbaumer, 1894; Phaeogenes similis Bridgman, 1881.

Material examined.

South Africa 1 female: South Africa Brits, Tvl. viii.X.1993 R. Kfir AcP 9336; ex pupae of Plutella xylostella on cabbage IIE 23016 (BMNH); 2 females: RSA [Republic of South Africa], S. DBerg, Sani Pass, 29°37'S, 29°23'E, Malaise trap, V. Kolyada and M. Mostovski coll., 2-5.03.04 (NMSA); 2 females: SAfr, KZN, PMB [Pietermaritzburg], Hilton, 29°32'30"S, 30°18'18"E, 1131m, 10-23.12.03, Malaise trap / garden M. Mostovski coll. (NMSA). Sweden 1 female: Sweden SK. Dalby. 13.v.1938. D. M.S. P. & J. F. P. B. M.1938-414 (BMNH).

Diagnosis.

Head black, body usually reddish–orange with apex of mesosoma, and base and apex of metasoma black; body sometimes far more extensively black marked; face, frons, vertex and temple shallowly and densely to moderately densely punctate; malar line long; antenna with 23-30 flagellomeres, slightly widened from basal third; mesosoma entirely polished and moderately setose; pronotum moderately punctate with a large median smooth area; mesopleuron densely punctate, speculum smooth; metapleuron coarsely punctate–rugose; mesonotum moderately punctate; scuto–scutellar groove smooth; scutellum carinate to mid–length; propodeum shallowly punctate rugose, area petiolaris concave, carination complete with area superomedia hexagonal, slightly wider than long; hind wing with distal abscissa of Cu1 discernible though faint; metasoma alutaceous but apical half of tergite 1 and base of tergite 2 longitudinally stri ate. B 4.5-5.3; A 3.1-3.2; F 3.3-3.7 (ranges measured on all observed material); HdWi 1.7; HfWi 1.2; Ci 1.8; Mi 0.9; Di 3.2; IOi 1.6; OOi 1.6; Fli1 3.5; Fli15 1.4; Fli23 1.1; OTi 0.4 (indices measured on BMNH South African female specimen).

Distribution.

South Africa, Mexico. Otherwise widespread from Europe and the Middle East to the Indo–Australian region, China and Japan. Introduced into numerous countries in the Indo–Australian and West Indies regions for biocontrol purpose.

Ecology.

Commonly used as a biological control agent of Plutella xylostella ( Lepidoptera : Plutellidae ) on cultivated cruciferous crops ( Brassica spp.). Also reared from Acrolepiopis assectella ( Lepidoptera : Plutellidae ) ( Kalmès and Rojas–Rousse 1980). The geographical origin of this species is not clear, neither is that of its host Plutella xylostella , which was originally considered to be European. Kfir (1998), based on an assessment of the origins of the moth’s host plants and the complex of natural enemies attacking the diamondback moth, suggested that the host species is from southern Africa. Diadromus collaris is very common in South Africa, where it reproduces sexually ( Kfir 1997, 1998), and in Europe, where it was reported to be thelytokous with mainly females known. It hence was speculated to be of African origin ( Kfir 1998). However, Liu et al. (2001) report that Diadromus collaris is arrhenotokous in Australia, Malaysia, China, Taiwan and France, and suggested that the diamondback moth originates in China. Diadromus collaris is probably present throughout the Afrotropical region; however, it is not present in Reunion, where the diamondback moth is only a minor pest (Rousse pers. obs.).