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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #92632
Title: COMPARISONS OF LABORATORY AND FERAL STRAINS OF SPODOPTERA FRUGIPERDA (J. E.SMITH) AND HELICOVERPA ZEA (BODDIE) IN LABORATORY AND FIELD BIOASSAYS

Author
item Carpenter, James
item WISEMAN, BILLY - USDA-ARS RETIRED

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Rearing fall armyworm and corn earworm in laboratory colonies has been an important part of research programs developing corn varieties resistant to these insect pests. Although natural populations or field collections of fall armyworm and corn earworm can be useful to researchers in plant resistance, laboratory colonies of these pests provide a reliable source of insects for these studies and, thereby, allow for an expanded research program. Because laboratory colonies of fall armyworm and corn earworm are relied upon by many researchers to conduct plant resistance studies, it is important that the insects in the laboratory colonies are physiologically and behaviorally equivalent to their wild counterparts. We found that insects reared in the laboratory over long periods of time and insects from the wild do not respond to resistance in plants in the same way. 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 3/4 wild colonies were established annually, and if insects from these 3/4 wild colonies were used in conducting laboratory and field bioassays.

Technical 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 3/4 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 3/4 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 the field studies, the 3/4 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 3/4 wild colonies were established annually, and if insects from these 3/4 wild colonies were used in conducting laboratory and field bioassays.