Fatty acid esters of phytol and geranylgeraniol have been isolated and identified from cotton as the primary feeding stimulants for the boll weevil. The objective of this study was to determine if feeding response to purified extracts containing these esters differed among cotton varieties. Fifteen commercial cottons developed throughout the cotton belt, with and without the presence of boll weevils, were investigated both chemically and biologically for these feeding stimulants.

We found significant differences in feeding response (biological assay) among the varieties. 'Paymaster', a variety developed in the Texas High Plains and 'Pima 5-6', which is grown at the highest elevation in Arizona, received the greatest feeding response. Eleven varieties were not significantly different from 'Stoneville 213'(ST 213) in the feeding assay. 'Acala-SJ5', developed in California was significant from all others in that it received the least amount of feeding.

We have confirmed that the ester fraction in ST 213 contains the primary feeding stimulants for the boll weevil. If the same is true for the other cotton varieties, then this assay method could be adapted in screening cotton for resistance to the boll weevil.