Dispersal and survival of early instars of European corn borer (Lepidoptera: Pyralidae) in field corn
1990
Ross, S.E. | Ostlie, K.R.
Cohorts of European corn borer, Ostrinia nubilalis (Hubner), from eggs infested on whorl-stage corn (Zea mays L.), were intensively sampled through fourth instar in 1986 and through fifth instar in 1987. In both years, central plants in plots (4 by 2 m, 55 plants) were infested with European corn borer egg masses to simulate a first-generation infestation. In 1986, one egg mass was placed in each plot, whereas in 1987, plots received one, two, or four egg masses. In both years, >50% of the recovered larvae were on the infested plant. Mean dispersal distance increased linearly with time in both years. However, maximum dispersal distance was independent of time in both years. In 1987, egg mass density had a significant linear effect on maximum dispersal distance but no effect on mean dispersal distance. The radius encompassing 90% of the recovered larvae included the infested plant and two plants on either side within the same row. Mortality occurred mainly within the first 48 h: 75.7% in 1986 and 82.9% in 1987. A logistic regression showed that egg and larval survival were independent of egg mass density. The number of tunnels produced per larva found at 8 d after infestation (considered equivalent to scouting) was 0.592. Knowledge of European corn borer dispersal and survival could be used to improve sampling plans and the calculation of economic thresholds.
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