Search results for "Bt cotton"
showing 3 items of 3 documents
Production and characterization of Bacillus thuringiensis Cry1Ac-resistant cotton bollworm Helicoverpa zea (Boddie).
2007
ABSTRACT Laboratory-selected Bacillus thuringiensis -resistant colonies are important tools for elucidating B. thuringiensis resistance mechanisms. However, cotton bollworm, Helicoverpa zea , a target pest of transgenic corn and cotton expressing B. thuringiensis Cry1Ac (Bt corn and cotton), has proven difficult to select for stable resistance. Two populations of H. zea (AR and MR), resistant to the B. thuringiensis protein found in all commercial Bt cotton varieties (Cry1Ac), were established by selection with Cry1Ac activated toxin (AR) or MVP II (MR). Cry1Ac toxin reflects the form ingested by H. zea when feeding on Bt cotton, whereas MVP II is a Cry1Ac formulation used for resistance se…
Binding of Bacillus thuringiensis toxins in resistant and susceptible strains of pink bollworm (Pectinophora gossypiella)
2003
Abstract Evolution of resistance by pests could cut short the success of transgenic plants producing toxins from Bacillus thuringiensis, such as Bt cotton. The most common mechanism of insect resistance to B. thuringiensis is reduced binding of toxins to target sites in the brush border membrane of the larval midgut. We compared toxin binding in resistant and susceptible strains of Pectinophora gossypiella, a major pest of cotton worldwide. Using Cry1Ab and Cry1Ac labeled with 125I and brush border membrane vesicles (BBMV), competition experiments were performed with unlabeled Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry1Ca, Cry1Ja, Cry2Aa, and Cry9Ca. In the susceptible strain, Cry1Aa, Cry1Ab, Cry1…
Insecticidal Genetically Modified Crops and Insect Resistance Management (IRM)
2008
Economically important crops, such as maize and cotton, have been transformed with genes encoding insecticidal proteins from Bacillus thuringiensis (Bt) to confer them protection against the most important insect pests. Of the 114 million hectares globally planted with GM crops in 2007, over one third are insect-resistant Bt crops, and the area keeps increasing every year. The potential for insects to evolve resistance to GM insecticidal plants is considered to be one of the main threats to this technology, since resistance to Bt sprayable products has been demonstrated. Insect resistance management plans for this new class of pesticides are encouraged and became mandatory in the USA. Of th…