Evaluation of natural and engineered resistance mechanisms in Solanum tuberosum for resistance to Phthorimaea operculella (Lepidoptera: Gelechiidae)

Potato tuber moth, Phthorimaea oprrculella Zeller, is a highly destructive pest of cultivated potato, Solanum tuberosum L., and is responsible for damage to both leaf and tuber tissues. Host plant resistance is a central component to developing ten integrated pest management program to control potato tuber moth. This research tested the efficacy of a codon-modified CryV-Bacillus thuringiensis (CryV-Bt) gene constitutively expressed in potato and the combined effect of CryV-Bt expression with natural host plant resistance mechanisms in potato. 'Lemhi Russet' and 2 lines with host plant resistance mechanisms, USDA8380-1 (leaf leptines) and L235-4 (glandular trichomes), along with the CryV-Bt-transgenic lines of each of these 3 genotypes were examined. Detached leaf bioassays were conducted to examine control of potato tuber moth. Nontransformed Lemhi Russet and L235-4 were susceptible to potato tuber moth, while 54% potato tuber moth mortality was found when first instar larvae fed on USDA8380-1 leaves. High levels of expression occurred in the CryV-Bt transgenic Lines, with up to 96% potato tuber moth mortality. These transgenic lines provide a germplasm base to examine combined insect-resistance mechanisms as a means to achieve durable host plant resistance.