Genetic variation inHeliothisin Australia: species identification and gene flow in the two pest species H. armigera (Hübner) and H.punctigeraWallengren (Lepidoptera: Noctuidae)

Abstract

AbstractGenetic (electrophoretic) variation was examined in the two pest species ofHeliothisfound in Australia,H. armigera(Hübner) andH. punctigeraWallengren. They could be differentiated by seven loci which enabled identification of individual eggs and small larvae not normally distinguishable by their morphology. The traditional criteria for distinguishing the larger larvae of the two species were shown to be unreliable. The genetic distance between the two species was 0·34 ± 0·02. The percentage of loci polymorphic in both species, 32%, and the mean heterozygosities, 11·3% forH. armigeraand 10·8% forH. punctigera, are lower than those reported in the American species,H. virescens(F.) andH. zea(Boddie). Populations throughout Australia were differentiated from each other, but there did not appear to be a marked geographic pattern to the variation. Genetic distances between populations ofH. armigerawere low (<0·01). It was concluded that the effective population size ofHeliothisis large and that significant gene flow probably occurs between widely separated regions.