COMPARISON OF TISSUES FROM SOLID- AND HOLLOW-STEMMED SPRING WHEATS DURING GROWTH: II. FOOD VALUES DETERMINED WITH THE PALE WESTERN CUTWORM, AGROTIS ORTHOGONIA MORR. (LEPIDOPTERA: NOCTUIDAE)

Abstract

Lyophilized stem tissues of Rescue and Thatcher wheat were inferior to lyophilized Thatcher sprouts or young leaves as diets for newly hatched or fifth-instar larvae of the pale western cutworm. Pith from solid-stemmed Rescue wheat was an inferior diet to either Thatcher stem or Rescue wall. Most newly hatched larvae lived for periods in excess of 24 days on pith diets but did not molt. Older stem tissues were nutritionally inferior to younger stem tissues. Neither the qualitative nor quantitative composition of 80% ethanol-soluble carbohydrates from the stems, leaves, and sprouts accounted for their relative value as diets for the cutworm. The amino acid composition of ethanol extracts and hydrolyzates of the different plant tissues was generally similar. Some differences were present and therefore amino acid composition cannot, as yet, be ruled out as a factor influencing the diets. Differences in the asparagine content of the plant tissues do not appear to be responsible for their effects on the larvae. There was no simple relationship between the ethanol-soluble nitrogen content of the tissues and their value as diets. The results suggest that a relatively high ethanol-soluble carbohydrate: total nitrogen ratio is an attribute of the tissues that were poor diets for the pale western cutworm.