MITOCHONDRIAL-DNA SEQUENCE VARIATION AMONG GEOGRAPHIC STRAINS OF DIAMONDBACK MOTH (LEPIDOPTERA, PLUTELLIDAE)

We examined genetic variation among 6 geographic strains of diamondbac k moth, Plutella xylostella (L.), using 365 base pairs of the mitochon drial gene encoding cytochrome oxidase I (COI). No sequence variation was detected within 5 of the 6 strains; 1 strain contained 2 haplotype s that differed by a single base substitution (0.27%). Sequence differ ences between strains of diamondback moth from Hawaii, the Philippines , and Pennsylvania ranged from 0 to 0.82%. With one exception, base pa ir substitutions among strains resulted in synonymous codons and did n ot alter amino acid sequence, Genetic divergence between strains of di amondback moth was not correlated with geographic distances between th e sources of each strain. Variation in COI among populations of diamon dback moth was similar to that found in other species of Lepidoptera a nd was substantially less than variation between diamondback moth and 2 undescribed Hawaiian Plutella species (5 and 10%, respectively). The sequences reported here provide benchmark data for related work, such as analysis of global patterns of resistance to Bacillus thuringiensi s in diamondback moth.