Responses of Corn Earworm Larvae to Maize Silks1
- N. W. Widstrom,
- B. R. Wiseman and
- B. R. McMillian2
Laboratory identification of maize (Zea mays L.) lines which have detrimental silk factors to the corn earworm [Heliothis zea (Boddie)] usually require several silk feedings over a period of 10 to 20 days. Seven maize lines were evaluated in a diallel crossing system for the number of larvae recovered from infested ears after 3 days, to determine the level of genetic variability for antibiosis, and to investigate the feasibility of using 3-day laboratory measurements to identify genotypes that show antibiosis in the field. Five of these lines were reported as having detrimental silk factors or antibiosis to the corn earworm and two were used as susceptible checks. Genetic differences existed among lines and crosses, but heritability estimates were less than 25%. Measurements of larval antibiosis expression on excised silks in the laboratory were neither consistent nor indicative of the field ratings for larvae recovered. Only Od3 and ZC 2451, of the seven lines tested, had a measurably better level of antibiosis expression than the checks when tested as an inbred. 81-1 was best in single-cross combinations. The data suggest that ears of inbreds generally provide a more hostile environment to corn earworm larvae than ears of single crosses. We conclude that the technique of measuring 3-day larval antibiosis expression does not provide sufficient time for larval antibiosis symptom manifestation and that an effective selection program of maize population improvement will require a longer ear-larvae association time.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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