Fluctuating asymmetry and immune function in a field cricket


  • Markus J. Rantala,

  • Jari J. Ahtiainen,

  • Jukka Suhonen

M. J. Rantala, J. J. Ahtiainen and J. Suhonen, Dept of Biological and Environmental Science, Univ. of Jyväskylä, P.O. Box 35, FIN-40351, Jyväskylä, Finland. Present address for MJR: Dept of Biology, Univ of California, Riverside, CA 92521, USA (marrant@dodomail.jyu.fi).


Recently, fluctuating asymmetry (FA) of morphological traits has attracted great attention as a short-cut measure of individual quality. Whereas there is some evidence that FA of sexual ornaments is negatively associated with immune function, studies concerning FA and immune function in non-ornamental traits are absent. Here, we tested whether FA of three non-ornamental traits in hind limbs is related to male immune function in a population of the Mediterranean field cricket, Gryllus bimaculatus. As different measures of male immune function, we used encapsulation rate and lytic activity. We found that a composite measure of FA (cFA) was negatively related to encapsulation rate. However, lytic activity was not related to cFA, but there was a tendency that males with higher body mass had higher lytic activity than males with lower body mass. Our results suggest that FA in non-ornamental traits indicates male immunocompetence in G. bimaculatus.