Detection of hybrids between introduced Torymus sinensis and native T-beneficus (Hymenoptera : Torymidae) in central Japan, using malic enzyme

Torymus sinensis is an introduced parasitoid used to control chestnut gall wasp, Dryocosmus kuriphilus. After the release of T. sinensis, morphologica lly-intermediate individuals between T. sinensis and the native parasitoid, T. beneficus appeared in the field, which were suspected to be the result of interspecific hybridization. In order to confirm whether the intermediat e individuals were hybrids of T. sinensis and T. beneficus (early-season st rain), their genotype for malic enzyme was analyzed by polyacrylamide gel e lectrophoresis. Nine individuals of 821 analyzed Torymus females showed a b anding pattern (FS genotype) of hybrids between T. sinensis and the early-s eason strain of T. beneficus. Of 388 individuals categorized as morphologic ally-intermediate, only 2 individuals showed the FS genotype.