Biotech Cotton Co-expressing Vip3AcAa and Cry1Ac Confers Protection against Cry1Ac-resistant Bollworm

Scientists from the Chinese Academy of Agricultural Sciences and partners conducted a study to investigate the performance of an insecticidal protein that has the potential to be used in combating cotton pests. The result is published in Transgenic Research.

The researchers developed a chimeric protein of Vip3Aa1 and Vip3Ac1, named Vip3AcAa, which exhibits a broader insecticidal spectrum. Then in a more recent study, they investigated the cross resistance and interactions between Vip3AcAa and Cry1Ac with three strains of cotton bollworm, one that is susceptible and two that are Cry1Ac-resistant, to determine if Vip3AcAa can be pyramided with Cry1Ac protein in cotton.

Results showed that progression of insect resistance to Cry1Ac toxin did not affect the sensitivity of Cry1Ac-resistant strains to Vip3AcAa. Mortality was found to be comparable to the expected mortality for all the combinations of Vip3AcAa and Cry1Ac tested, which indicate independent activity between these two insecticidal proteins. When the vip3AcAa and cry1Ac genes were both introduced into cotton, mortality rates of Cry1Ac resistant bollworms (larvae) that fed on this new cotton increased significantly compared with larvae fed on non-Bt cotton and cotton producing only Cry1Ac.

Based on the findings, Vip3AcAa protein is a good choice for a "pyramid" strategy for pest resistance management in cotton.

Read the research article in Transgenic Research.