Variation among individual Helicoverpa punctigera collected from 6 widespread Australian sites has been assessed for 250bp of DNA sequence from the AT-rich region of mitochondrial DNA. Twelve different genetic variants were detected, most differing from the common sequence by only a single base change. Generally the common sequence predominated in all samples with 1 or 2 moths out of 10 showing a variant sequence. Of interest were two collecting sites, one in the far north, where different unique variants occurred at high frequency. These data suggest genetic homogeneity across most of the species range, which is consistent with the high levels of migration known for this species. However the high frequency of unique variants at some sites suggested that isolation and genetic differentiation does occur. Further sampling is suggested to help identify such sites.

One sample of the other significant pest species, H. armigera indicated higher levels of genetic variation. In this species many more genetic types occurred for a given sample size and no one type predominated in frequency. These results suggest that this less vagile species may have larger effective population size, higher mutation rates, or a different pattern of natural selection operating. This species is less likely to show spatial homogeneity of mtDNA type.