Relationships of glands, cotton square terpenoid aldehydes, and other allelochemicals to larval growth of Heliothis virescens (Lepidoptera: Noctuidae)

Female moths of the tobacco budworm, Heliothis virescens (F.), oviposit in terminals of the cotton plant, Gossypium hirsutum (L.). The hatched larvae feed in the terminal area, then migrate to small squares (buds) where they feed and finally burrow into and feed on the anthers, where they grow rapidly. They attempt to avoid feeding on gossypol glands during the first 48 h after hatching. When tobacco budworm neonate larvae were fed squares of highly glanded lines, growth was decreased by 25-75 %. The number of glands in calyx and bract tissues of squares of resistant lines was significantly higher than in susceptible lines. The difference was greatest in the calyx crown where the ratio in resistant to susceptible lines was 10-20 fold. The calyx crown of highly glanded resistant lines also was high in terpenoid aldehydes. High pressure liquid chromatography data showed that the gossypol content of susceptible and resistant glanded lines is equal, whereas three other terpenoid aldehydes, hemigossypolone and heliocides H1 and H2 are greatly increased in resistant lines, and they are presumably more closely associated with resistance