Seasonal Phenology of Allelochemicals in Cotton and Resistance to Bollworm (Lepidoptera: Noctuidae)

Abstract

Seasonal phenology of condensed tannin quantity and quality, and terpenoid aldehyde quantity of 4 Upland cotton phenotypes were determined in the field during 1983. Tannin quantity and quality gradually increased from cotyledonary stage to a peak in late bloom. At the one-third-grown square stage of growth, we observed a sudden drop in both tannin quantity and quality followed by rapid recovery. Terpenoid aldehyde quantity was highest at the initiation of fruiting following which it dropped significantly and remained relatively constant for the remainder of the plants' life history. Fruit damage by bollworm, Heliothis zea (Boddie), at the one-third-grown square stage of growth was found to be highly negatively correlated with tannin quality. Terpenoid aldehyde quantity was negatively correlated with bollworm damage at the second week of bloom. Implications for host plant resistance and IPM are discussed.