ARS | Publication request: CONTROL OF BOLLWORMS IN BT COTTON USING GEMSTAR LC BIOLOGICAL INSECTICIDES

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 20, 2000
Publication Date: N/A

Interpretive Summary: The extent of the insect pest problem is changing as growers adopt the Bt -transgenic cotton technology. Bt cotton has worked well at controlling tobacco budworms, but has proven less effective against cotton bollworms. The microbial insecticide Gemstar LC that has been used to control cotton bollworms was tested at lower treatment rates against cotton bollworms on Bt cotton. In our study the cotton bollworms that survive on Bt cotton were equally susceptible to the virus applied at lower treatment rates. The results of this research are important to the grower because they may lead to a less expensive control strategy for cotton bollworm on Bt cotton that will be environmentally safe and economically sound.

Technical Abstract: Results of a study in 1999 were reported that assessed the effect of B.t. -transgenic cotton on the cotton bollworm-Helicoverpa zea nucleopolyhedrovirus interaction, and evaluated the effectiveness of cotton. The B.t.-treated diet used in the laboratory study reduced the growth rate of cotton bollworms and caused an additive mortality response when combined with Gemstar. Larval counts of H. zea in field studies were significantly lower on B.t. cotton for all treatments, while H. zea larvae in all virus treatments showed lower survival.