The objective of this work was to evaluate the production of Cry1Ac, a toxin of Bacillus thuringiensis (Bt), in genetically modified cotton plants (Bt cotton), and the feeding and oviposition preference of Alabama argillacea confined to Bt cotton and non Bt cotton under water stress. The varieties of Bt cotton - Acala 90B and NuOpal, and non Bt - Acala 90 and DeltaOpal - were cultivated in microplots, under stress and no stress conditions. Toxin production was evaluated in Bt cotton leaves and reproductive parts. For the oviposition choosing test, A. argillacea moths were released into a large screen cage which contained the four cotton varieties. After 72 hours, the number of eggs was quantified. For the feeding preference, 3-day and 10-day-old larvae were evaluated. The production of Cry1Ac toxin was higher in leaves of the plant apical part of the two varieties under water stress, and it was similar in the bracts and boll husks. Moths and caterpillars of A. agillacea do not distinguish between Bt and non Bt cotton for feeding and oviposition choosing, respectively. However, moths show preference for ovipositing on plants under no water stress.
Bacillus thuringiensis; Gossypium hirsutum; cotton leafworm; herbivory; plant resistance
