THE BERTHA ARMYWORM, MAMESTRA CONFIGURATA (LEPIDOPTERA: NOCTUIDAE). EFFECTS OF DIETARY LINOLENIC ACID ON PUPAL SYNDROME, WING SYNDROME, SURVIVAL, AND PUPAL FAT COMPOSITION

Abstract

AbstractLinolenic acid, added to a defatted diet in which wheast and alfalfa meal were the only protein sources, optimally reduced wing syndrome (defined as crumpled wings) in Mamestra brassica Walker at 1.1 mg/g (w/w dry wt.) of diet, increased survival to pupa at 2.2 mg/g, and reduced pupal syndrome (defined as improper formation of the 4th abdominal sternite) and increased survival to adult at 5.8 mg/g. Pupal weight increased and incidence of diapause decreased as dietary linolenic acid increased. Linoleic acid substituted for linolenic acid only in survival to the pupal stage. Pupae from larvae fed artificial diets had more fat (20.6–25.5% dry wt.) than pupae from larvae fed rape leaves (16.5%). Absolute levels of linolenic acid increased in pupae in proportion to dietary levels including pupae from larvae reared on rape leaves but the relative amount of linolenic acid sequestered in pupae from leaf-fed larvae was greater.Pupal syndrome is a sensitive indicator of dietary adequacy and its occurrence is affected by dietary linolenic acid and possibly other fat soluble components.