Colorado potato beetle, Leptinotarsa decemlineataSay, is a serious pest of potato, Solanum tuberosum L., readily adapting to insecticides. Therefore, it is a model organism for investigating the effectiveness of combining host plant resistance into a single cultivar to manage adaptation to host plant resistance. The larval (first to fourth instar) consumption, growth and survival were assessed on four potato lines: non-transformed control (Yukon Gold), leptines (USDA8380-1), Cry3A (Yukon Gold-BtCry3A), and leptines combined with Cry3A (80-1-BtCry3A) for three Colorado potato beetle strains: susceptible, insecticide resistant, and Bacillus thuringiensis-Cry 3A resistant in a 5 d no-choice detached leaf assays. For all instars and all beetle strains, the control had more feeding than all three clones. For all instars of all beetle strains, leptines deterred feeding greater than the control. For all instars of all beetle strains, Cry3A deterred feeding greater than both the control and leptines. For susceptible fourth instars and third and fourth insecticide resistant instars, leptines+Cry3A deterred feed greater than the control, leptines and Cry3a. For susceptible larvae, mortality differed little between the control and leptines; however for insecticide resistant larvae, morality was higher on the leptines than the control for first, second and third instars (11.4%-22.2%). The BtCry3A and BtCry3A+leptines had greater mortality than leptines or control (61.4-95.3%). For third and fourth susceptible instars and second, third and fourth insecticide resistant instars, BtCry3A+leptines had greater mortality than BtCry3A. Combining leptines with BtCry3A provides greater host plant resistance than leptines or Cry3A alone.
Species 1: Coleoptera Chrysomelidae Leptinotarsa decemlineata (Colorado potato beetle)
Keywords: Bacillus thuringiensis, leptine glycoalkaloids
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