DISPERSAL AND SURVIVAL OF EARLY INSTARS OF EUROPEAN CORN-BORER (LEPIDOPTERA, PYRALIDAE) IN FIELD CORN

Cohorts of Ostrinia nubilalis from eggs infested on whorl-stage Zea mays were intensively sampled through 4th instar in 1986 and through 5th instar in 1987. Mean dispersal distance increased linearly with time, but maximum dispersal distance was independent of time. In 1987, egg mass density had a significantly 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 2 plants on either side within the same row. Mortality occurred mainly within the first 48h: 75.7% in 1986 and 82.9% in 1987. Egg and larval survival were independent of egg mass density. Number of tunnels produced per larva found at 8d after infestation (considered equivalent to scouting) was 0.592. -from Authors