Damage to apple cultivars by races of European corn borer (Lepidoptera: Pyralidae)

Experiments were conducted in a growth chamber, greenhouses, and orchards to determine the level of infestion, behavior, and survival of larvae from European corn borer, Ostrinia nubilalis (Huebner), races and a population on apple cultivars. Field infestations of apple shoots with either eggs or first instars of three races yielded no establishment. In a greenhouse test with potted scions, however, a bivoltine race responding to a predominately E pheromone mix, produced significantly more dead shoots than other infestations. Greatest shoot mortality in the greenhouse was caused by infestations with fourth instars. In growth-chamber tests, neonate larvae displayed a low degree of establishment of fruits, but where there was establishment, fruit entry increased proportionately with instar.