Syngenta is seeking commercial registration for VipCot? cotton, a pyramided transgenic cotton trait that expresses two insecticidal proteins derived from Bacillus thuringiensis Vip3A and Cry1Ab. Both proteins are highly effective against two key cotton pests, Helicoverpa zea cotton bollworm; and Heliothis virescens, tobacco budworm. To investigate the role of VipCot? cotton in delaying the development of resistance in these pests to transgenic Bt traits, Syngenta has performed studies to determine the dose of proteins expressed in VipCot? and evaluate the potential for cross-resistance between the component proteins. Following United States Environmental Protection Agency (US EPA) high dose methods 1 and 4, VipCot? was shown to express a high dose of proteins for H. zea and H. virescens. VipCot? was also confirmed to express a high dose of proteins for H. zea through US EPA Method 5. Additionally, all the data collected to date verify a lack of cross-resistance between Vip3A and Cry proteins. These two key pieces of information indicate that VipCot? cotton should be very durable under the currently mandated high dose plus refuge insect resistance management strategy.