Flight capacity: genetic determination and physiological constraints in a migratory moth Mythimna separata

Flight capacity of the oriental armyworn Mythimna separata (Walker) (Lepidoptera: Noctuidae) was estimated by a new tethered flight technique. Samples of a migrant population showed a substantial proportion of ‘long fliers’. Heritability of flight capacity was found to be significant ( h 2 = 0.27). Female moths from a line selected for long pre‐reproductive period (PRP) showed greater flight capacity than those from a short PRP line. This difference was not apparent among males. Onset of calling behaviour inhibited the expression of flight capacity in females showing a clear ‘oogenesis‐flight syndrome’. These results are discussed in relation to seasonal migration in eastern China and the mechanisms involved in the migratory strategy of this species.