Behavioral studies have shown that young tobacco budworm larvae prefer to feed on the calyx margin area (calyx crown) of the square. In most cultivated cotton cultivars this feeding site is void of gossypol glands. Behavioral studies have also confirmed that first instar larvae avoid feeding on gossypol glands. We have developed doubled haploid lines with high gossypol gland density on the calyx crown. The objective of this study was to measure the growth of tobacco budworm larvae fed squares from lines with high and low gland density in the calyx crown. Several doubled haploid lines were crossed with Stoneville 213 and Stoneville 825 varieties. Plant selections were made from these crosses for high and low gossypol gland density. Neonate tobacco budworm larvae were placed on excised squares from 8 high and 8 low density lines and allowed to feed. After seven days the larvae were weighed. Tobacco budworms that fed on high gland density squares weighed significantly less than those fed on low density squares.

Gossypol glands are controlled genetically. With a phenotypic character such as gossypol glands, breeders can manipulate gland density. Results from these studies suggest that selection for resistance to tobacco budworm in cotton can be accomplished by crossing and selecting plants which have high gland density in the calyx crown area. This may be obtained without increasing total gossypol.