MIGRATION IN THE GRASSHOPPER MELANOPLUS SANGUINIPES (FAB.). II. INTERACTIONS BETWEEN FLIGHT AND REPRODUCTION

¹ Department of Zoology, University of Texas at Austin, Austin, Texas 78712

Prolonged flight behavior in females of the grasshopper, Melanoplus sanguinipes (Fab.), decreases as ovarian tract weight increases relative to body weight. However, reproductive maturation does not always permanently terminate the migratory phase of the grasshopper's life cycle; long flights are also made after ovipositions. We examine the hypothesis that migration (measured as long-duration tethered flight behavior) decreases reproductive potential, either by delaying first oviposition or by decreasing production of egg pods. No negative effects of flight on oviposition were observed. Instead, age at first oviposition tended to decrease in females flown repeatedly compared to those flown only twice. Further, oviposition was greatly enhanced in females flown for several hours relative to unflown controls. We suggest that selection pressure for rapid and successful colonization has resulted in the evolution of a suite of characters including enhanced migratory behavior and accelerated reproduction in highly migratory populations.