Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) kill some key insect pests, but evolution of resistance by pests can reduce their efficacy. The main approach for delaying pest adaptation to Bt crops uses non-Bt host plants as "refuges" to increase survival of susceptible pests. To delay evolution of pest resistance to transgenic cotton producing Bt toxin Cry1Ac...

China is one of the largest producers of cotton in the world. Insect pests such as cotton bollworm, cotton aphid, and mirids are the major factors that contribute to a decrease in cotton production. Transgenic cotton that expresses a gene derived from the bacterium Bacillus thuringiensis (Bt) has been deployed for combating cotton bollworm since 1997 in China, and expanded rapidly to 3.7 millio...

Widespread planting of crops genetically engineered to produce insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) imposes selection on many key agricultural pests to evolve resistance to Bt. Fitness costs can slow the evolution of Bt resistance. We examined effects of entomopathogenic nematodes on Þtness costs of Bt resistance in the pink bollworm, Pectinophora gossypiella (Saun...

Transgenic Bt cotton may have reduced susceptibility to aflatoxin contamination as a result of pink bollworm resistance. During 1995 and 1996, Bt cottonseed from several commercial fields in Arizona contained aflatoxin levels unacceptable for dairy use. Comparison of cottonseed with and without BGYF (bright-green-yellow fluorescence) from one highly contaminated (>6,000 ppb aflatoxin Bj) Bt see...

Widespread planting of crops genetically engineered to produce insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) imposes selection on many key agricultural pests to evolve resistance to Bt. Fitness costs can slow the evolution of Bt resistance. We examined effects of entomopathogenic nematodes on fitness costs of Bt resistance in the pink bollworm, Pectinophora gossypiella (Sau...

Transgenic crops producing Bacillus thuringiensis (Bt) toxins kill some key insect pests and thus can reduce reliance on insecticides. Widespread planting of such Bt crops increased concerns that their usefulness would be cut short by rapid evolution of resistance to Bt toxins by pests. Pink bollworm (Pectinophora gossypiella) is a major pest that has experienced intense selection for resistanc...

A large percentage of Bollgard cotton is treated for bollworms [Helicoverpa zea (Boddie)] with little information about economic losses from these infestations. The impact of bollworm infestations on maturity and yield of Bollgard cotton was determined. Infestations of 1-d-old bollworm larvae were established on non-Bollgard and Bollgard cottons in large field cages. Treatments included three a...

The pink bollworm, Pectinophora gossypiella (Saunders), is one of the most serious pests of cotton worldwide causing losses in both yield and quality. Control with conventional insecticides is difficult because the pest is well protected within cotton squares and bolls. Furthermore insecticide costs are high and applications of broad-spectrum materials have contributed to outbreaks of secondary...

Research was conducted to quantify the development of the corn earworm (= bollworm), Helicoverpa zea (Boddie), on two different transgenic cotton cultivars (DP 50B and NuCOTN 33B) that contained different levels of the Cry1Ac endotoxin from the soil bacterium, Bacillus thuringiensis Berliner. Using a field cage, an inverse relationship between the amount of Cry1Ac among cultivars versus the wei...

Crops genetically engineered to produce Bacillus thuringiensis toxins for insect control can reduce use of conventional insecticides, but insect resistance could limit the success of this technology. The first generation of transgenic cotton with B. thuringiensis produces a single toxin, Cry1Ac, that is highly effective against susceptible larvae of pink bollworm (Pectinophora gossypiella), a m...