Evidence for obligate migratory flight behavior in young European corn borer (Lepidoptera: Crambidae) females.

European corn borer, Ostrinia nubilalis, flight behavior was examined in laboratory experiments. Adults were each tethered to 1 of 16 round-about flight mills in an environmental chamber, and the data were relayed to a computer. Parameters analyzed included duration, distance, and speed of the longest continuous flight and total flight time during an 8-h night. Comparisons were made between unmated and mated adults of both sexes at different ages up to 5 d after emergence. For unmated females, duration of the longest flight was highest the first night after emergence, declining significantly by 5 d of age. In contrast, duration of the longest flight for males was lowest at 1 d of age, increasing significantly by 3 d of age. Flight speed of females was roughly twice that of males at all ages. Mating did not affect flight behavior of either sex at any age tested, but mated adults could not be tested before 2 d of age because the first night was needed for mating. The pattern of age-specific flight behavior suggests that unmated females engage in obligate migratory flight the first full night after emergence. The median duration of this flight was approximately 2 h in our experiments, with some adults flying continuously for the full 8 h of darkness. Females of other ages and males of all ages tested were capable of long-duration flights, but they more likely represent foraging flight. These results help explain the high dispersal rate of newly emerged adults from release sites in field experiments.