Comparisons Of Laboratory And Feral Strains Of Spodoptera frugiperda And Helicoverpa zea (Lepidoptera: Noctuidae) In Laboratory And Field Bioassays

Abstract

The effects of resistant corn entries and resistant silk-diets on the growth and development of fall armyworm and corn earworm from a laboratory and a I wild colony were compared in laboratory and field studies. For both species, there were significant interactions between insect strain and diet treatments. Compared to the laboratory strains, the I wild strains produced lighter larvae and required longer developmental times when reared on diets with and without resistant silks. Larval growth of both insect strains was significantly retarded by the addition of resistant silks to the diets. In field studies, the I wild strains generally performed better than the laboratory strains. For both insect species, interactions between insect strains and corn lines were observed. Strain differences for all measured parameters were greater for the corn earworm than for the fall armyworm. Results from these studies indicate that research on plant resistance for the fall armyworm and the corn earworm would better predict the relative levels of resistance among different corn lines and among different silk diets if I wild colonies were established annually, and if insects from these I wild colonies were used in conducting laboratory and field bioassays.