Dispersal–reproduction trade‐off in the leaf beetle Galerucella grisescens.

Dispersion–reproduction trade‐offs are important to explore the evolutionary mechanism of dispersal strategies and the adaptive significance of dispersion in insects. In our previous study, variations in hindwing length were found in Japanese populations of the leaf beetle Galerucella grisescens (Joannis) (Coleoptera: Chrysomelidae). They were distinctly divided into either long‐winged (LW) or short‐winged (SW) morphs in the field. The LW morphs were distributed widely in Japan, whereas the SW morphs were found in restricted areas in Honshu, the main island of Japan. We examined the possible existence of trade‐offs between dispersion and reproduction in G. grisescens by laboratory experiments. Larval duration and adult body size (head width) were not significantly different between LW and SW strains, but adult body weight was larger in some LW strains than in SW strains, most likely due to the size of hindwings and legs as well as to the development of flight muscles. Although the pre‐oviposition period was not significantly different among strains, female longevity and fertility were significantly higher in SW than in LW strains. Long‐winged individuals displayed flutter behaviours, suggesting their flight dispersal abilities, but SW individuals did not. Femurs of LW individuals were significantly longer on all legs compared to SW strains and the former walked faster than the latter. The present results indicate the presence of a dispersion–reproduction trade‐off in G. grisescens, in which SW strains have advantages in reproductive abilities and LW strains in dispersal abilities. [ABSTRACT FROM AUTHOR]