The parasitoid complex [Hym.: Ichneumonoidea] ofToxoptera aurantii [Hom.: Aphidoidea] in the Mediterranean area

The parasitoid complex of the Black Citrus Aphid,Toxoptera aurantii (B.d.F.) in the Mediterranean area has been complemented on the basis of samples collected in South Italy and Lebanon. To the complex presently belong 10 Ichneumonoid species of the generaAphidius Nees,Diaeretiella Staryý,Ephedrus Haliday,Lipolexis Förster,Lysiphlebus Förster,Praon Haliday andTrioxys Haliday. Of these,Aphidius colemani Viereck, in spite of its wide distribution in the Mediterranean region, seems to be restricted to Near East (Israel and Lebanon) asT. aurantii parasitoid. The nearctic speicesLysiphlebus testaceipes (Cresson) is localized in Spain, South France, Corsica, Central and South Italy, including Sicily. In Italy, this endoparasitoid has heavily interfered with the local dominant congeneric speciesLysiphlebus confusus Tremblay & Eady andLysiphlebus fabarum (Marshall). The possible associative relationships betweenLysiphlebus testaceipes andL. fabarum have been examined in the samples collected in South Italy. The results of the examination suggest that the 2 species are negatively associated with each other, i.e. the abundance of 1 of the 2 species makes it more likely that the other will decrease in numbers. Moreover, the data concerning the relative abundance of both species in the same area indicate that a shift may have occurred in favour ofL. testaceipes between 1977 and 1978. The nearctic parasitoid seems to be able to displace the 2 congeneric species by a competitive biological mechanism which is still in course of investigation.