The cotton bollworm Helicoverpa armigera is the major insect pest targeted by cotton genetically engineered to produce the Bacillus thuringiensis toxin (transgenic Bt cotton) in the Old World. The evolution of this pest's resistance to B. thuringiensis toxins is the main threat to the long-term effectiveness of transgenic Bt cotton. A deletion mutation allele (r(1)) of a cadherin gene (Ha_BtR) ...

Poplar-cotton agro-ecosystems are the main agricultural planting modes of cotton fields in China. With increasing acres devoted to transgenic insect-resistant poplar and transgenic insect-resistant cotton, studies examining the effects of transgenic plants on target and non-target insects become increasingly important. We systematically surveyed populations of both target pests and non-target i...

The popularity of genetically modified insect resistant (Bt) cotton has promoted large scale monocultures, which is thought to worsen the problem of crop genetic homogeneity. Information on genetic diversity among Bt cotton varieties is lacking. We evaluated genetic divergence among 19 Bt cotton genotypes using simple sequence repeat (SSR) markers. Thirty-seven of 104 surveyed primers were...

Transgenic crops producing Bacillus thuringiensis (Bt) proteins kill key insect pests, providing economic and environmental benefits. However, the evolution of pest resistance threatens the continued success of such Bt crops. To delay or counter resistance, transgenic plant "pyramids" producing two or more Bt proteins that kill the same pest have been adopted extensively. Field populations of t...

The pink bollworm, Pectinophora gossypiella (Saunders), first invaded Arizona in 1926 and has been a key pest of cotton, Gossypium hirsutum L., since the early 1960s. A broad range of tactics has been developed to manage this pest including a variety of cultural methods, mating disruption via pheromones, sterile insect release, and plant resistance. Transgenic cotton producing the insecticidal ...

Transgenic cottons producing Cry toxins from Bacillus thuringiensis (Bt) provide for control of lepidopteran pests and were first commercially grown in Australia, Mexico and the USA in 1996. As of 2007, a total of six additional countries (Argentina, Brazil, China, Colombia, India, and South Africa) now grow Bt cotton on a total production area of 14 million hectares. The technology primarily p...

We created a deterministic, frequency-based model of the evolution of resistance by corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), to insecticidal traits expressed in crops planted in the heterogeneous landscapes of the southern United States. The model accounts for four generations of selection by insecticidal traits each year. We used the model results to investigate the inf...

To delay evolution of pest resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt), the "pyramid" strategy uses plants that produce two or more toxins that kill the same pest. We conducted laboratory diet experiments with the cotton bollworm, Helicoverpa armigera, to evaluate cross-resistance and interactions between two toxins in pyramided Bt cotton (Cry...