AGE-RELATED AND DENSITY-RELATED OVIPOSITION BEHAVIOR OF THE EUROPEAN CORN-BORER, OSTRINIA-NUBILALIS (LEPIDOPTERA, PYRALIDAE)

Age-related oviposition patterns of Ostrinia nubilalis were studied at three population densities in the laboratory by releasing newly eclos ed adults in wire-screened cages and analyzing their oviposition throu ghout the adult stage with digital analysis. Oviposition sequences of individual females depositing egg masses were documented on the third and seventh nights after eclosion with a video camcorder. During a seq uence, a female produced an egg in an average time of 15 or 26 s on th e third and seventh nights, respectively, and completed depositing an egg mass the size of 20-39 eggs in an average time of 316 and 525 s, r espectively. Females were not easily disturbed during egg mass deposit ion and pulsated their abdomen before deposition of each egg. Females produced few egg masses the first night after eclosion. Oviposition in creased on nights 2 and 3 but declined steadily thereafter as females matured. Females older than 6 nights produced fewer egg masses; the pr oportion of egg masses with fewer than 20 eggs increased gradually. By the end of the adults' lifetime, nearly 100% of the egg masses had fe wer than 20 eggs. The data are fundamental to our research to define t he role of phytochemicals in modifying oviposition behavior of the Eur opean corn borer.