Oviposition behaviour and egg distribution of the European corn borer, Ostrinia nubilalis, on maize, and its effect on host finding by Trichogramma egg parasitoids

Oviposition behaviour and egg distribution of Ostrinia nubilalis is reviewed based on published information and new research. The position of egg masses of O. nubilalis on maize plants and leaves were sampled in the field. Most egg masses were found on the lower leaf side, on the middle part of the leaf or close to the stem, and close to the mid-rib. Direct observations of oviposition behaviour were made in laboratory and field cages. O. nubilalis moved very little on the plants and only 10 % of the females that landed on the plants oviposited. The number of actual ovipositions was quite low compared to the number of landings, with females walking only a few centimetres if at all. Shed scales of adult moths were not abundant near egg masses with only 37% of egg masses associated with scales and 45% with only a few scales. Many scales were found on other places of the plants. At the leaf and plant level, scales might serve as a useful host-cue to Trichogramma brassicae, an egg parasitoid of O. nubilalis. However, scales are not an indicator for the presence of egg masses in their immediate vicinity