ALLELOCHEMICAL CONTENT OF SELECTED POPCORN SILKS - EFFECTS ON GROWTH OF CORN-EARWORM LARVAE (LEPIDOPTERA, NOCTUIDAE)

Silks of popcorn, Zea mays L., in the Eldredge collection were evaluated or effects on growth of larvae of the com earworm, Helicoverpa zea (Boddie), and assayed for content of maysin, chlorogenic acid, apimaysin, and 3'-methoxymaysin. The weights of 9-d-old larvae ranged from 8 mg on 'PI340856' to 952 mg on 'PI340855'. Silks from about one-third of the popcorn collection produced com earworm larvae equal to or smaller than larvae that fed on silks of the resistant standard, 'Zapalote Chico'. Content of maysin, a luteolin-C-glycoside, ranged from zero for eighteen PIs to 1.128% for 'PI340856'. Significant negative correlations were found between contents of all four allelochemicals assayed and larval weights. Silks of 'PI340853' had no detectable levels of any of the allelochemicals assayed, yet they produced larvae with an average weight of only 37 mg. Silks of several introductions had higher concentrations of chlorogenic acid, apimaysin, and 3'-methoxymaysin than silks of 'Zapalote Chico'.