Genetic mapping of resistance to Bacillus thuringiensis toxins in diamondback moth using biphasic linkage analysis

Transgenic plants producing environmentally benign Bacillus thuringiensis ( Bt) toxins are deployed increasingly for insect control, but their efficacy will be short-lived if pests adapt quickly. The diamondback moth (Plutella xylostella), a worldwide pest of vegetables, is the first insect to evolve resistance to Bt toxins in open-field populations. A recessive autosomal g ene confers resistance to at least four Bt toxins and enables survival with out adverse effects on transgenic plants. Allelic variants of this gene con fer resistance in strains from Hawaii, Pennsylvania, and the Philippines. H ere we exploited the biphasic nature of Lepidopteran genetic linkage to map this gene in diamondback moth with 207 amplified fragment length polymorph isms as DNA markers. We also cloned and sequenced an amplified fragment len gth polymorphism marker for the chromosome containing the Bt resistance gen e. The results provide a powerful tool for facilitating progress in underst anding, monitoring, and man aging resistance to Bt.