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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #82388
Title: GROWTH AND DEVELOPMENT OF CORN EARWORM (LEPIDOPTERA: NOCTUIDAE) LARVAE REARED ON TWO POPCORN SILK-DIETS

Author
item Wiseman, Billy
item Carpenter, James

Submitted to: International Journal of Allelopathy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: The corn earworm is a perennial pest of field crops in the southern United States. Resistant corn silks can provide a biological, economical, ecological, and socially feasible means of limiting losses by the corn earworm. Laboratory studies were conducted to determine whether growth inhibition of corn earworm larvae fed resistant silks were due to a feeding deterrent or other factors. We conclude that the growth inhibition factor in the resistant silks of PI 340856 and PI 340853 is not due to a feeding deterrent but to an antinutritive factor that binds the protein or results in the degradation of essential amino acids, causing the larvae to excrete a large quantity of protein rather than use it. This contribution adds to the scientific knowledge of the biological basis of the resistant silks of PI 340856 and PI 340853 to corn earworm larval feeding. 

Technical Abstract: Resistant popcorns ('PI 340856' and 'PI 340853') containing maysin and isoorientin, respectively, were studied to determine whether growth inhibition responses of the corn earworm larvae, Helicoverpa zea (Boddie), on these popcorn silks is the result of a feeding deterrent or other factors. Neonates fed for 7 and 8 d on silk- diets of the two popcorns weighed, consumed diet and excreted frass significantly less than larvae fed on control diets. Fourth instars with the same initial weight gained significantly less, required longer to pupate, and had smaller pupae when reared on silk-diets of the popcorns compared to the performance of larvae on control diets. Yet, diet consumption and frass production were greater for fourth instars feeding on the popcorn silk-diets. Fifth instars fed the silk-diets weighed similarly after 24 h while consuming and excreting a greater quantity of diet. Though the chemical basis of resistance in the two popcorns and some of the measurable feeding responses reported were different, the results are quite similar to those reported for corn earworm neonate, fourth and fifth instars fed silk-diets of Zapalote Chico. These studies demonstrate that the growth inhibition factor in these popcorns is not caused by a feeding deterrent, but rather a antinutritive factor.