Use of malic enzyme to detect hybrids between Torymus sinensis and T. beneficus (Hymenoptera: Torymidae) attacking Dryocosmus kuriphilus (Hymenoptera: Cynipidae) and possibility of natural hybridization

Hybrids between the early-season strain of Torymus beneficus and T. sinensis, in which the malic enzyme (ME) is fixed at the F and S alleles, respectively, can be discriminated from their parents by the enzyme banding pattern using PAG electrophoresis. The ME locus of hybrids between the late-season strains of T. beneficus and T. sinensis is fixed at the S allele. Females of Torymus spp. collected in the field at Tsukuba had various ratios of ovipositor sheath length to thorax length and three ME genotypes: SS, FS and FF. Detection of FS in this population indicates that natural hybridization occurs between early-season strains of T. beneficus and T. sinensis.