A comparison between two strains from Japan and Europe of Aphidius ervi

A European strain of Aphidius ervi shall be introduced into Japan for the c ontrol of Macrosiphum euphorbiae on greenhouse tomatoes. We compared this s train, which is originating from The Netherlands (EVP), with a native strai n from Hokkaido, Northern Japan (SPR) in several characteristics. The perce ntage of parasitism of SPR and EVP was significantly different, when attack ing three aphid species: 13% and 30% on M. euphorbiae on tomato, 68% and 93 % on Acyrthosiphon pisum on broad bean and 10% and 42% on Aulacorthum solan i on sweet pepper, respectively. SPR and EVP differed morphologically (in t he colouration of the petiole) and in the esterase banding patterns. Furthe rmore, cross mating experiments showed that SPR and EVP are partially repro ductively isolated from each other. Complete reproductive isolation is evid ent in the one direction cross (EVP females and SPR males).