1985 Fall Armyworm Symposium: Plant Resistance: Influence of Four Corn Cultivars on Fall Armyworm (Lepidoptera: Noctuidae) Establishment and Parasitization

S. D. Pair, B. R. Wiseman, A. N. Sparks


Establishment of fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), larvae was significantly lower on resistant `Antigua 2D-118' and `Pioneer X304C' than upon susceptible `Cacahuacintle X's' and `Pioneer 3369A' corn lines. There was a significant effect between years and rates of artificial infestation on FAW larval establishment and parasitization. A density-dependent response of parasitoids was indicated in 1982 but not in 1983 when fewer larvae became established in the 2nd planting, possibly due to a combination of rainfall and advanced plant development. Greater numbers of larvae established when plants were artificially infested with 10 larvae per plant compared with 20 or 40 larvae. Although `Pioneer X304C' and `Antigua 2D-118' had significantly fewer larvae in post-infestation counts, rates of parasitization were higher than for larvae observed on susceptible corn lines. A probable cause was that FAW larvae on corn lines with nonpreference-type resistance exhibited more movement and were more exposed to parasitoids. Campoletis sp. was the primary parasitoid species involved in both years.

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