Present address: Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Selection for cuticular melanism reveals immune function and life-history trade-offs in Spodoptera littoralis
Version of Record online: 7 AUG 2008
© 2008 The Authors. Journal Compilation © 2008 European Society For Evolutionary Biology
Journal of Evolutionary Biology
Volume 21, Issue 6, pages 1744–1754, November 2008
How to Cite
COTTER, S. C., MYATT, J. P., BENSKIN, C. M. H. and WILSON, K. (2008), Selection for cuticular melanism reveals immune function and life-history trade-offs in Spodoptera littoralis. Journal of Evolutionary Biology, 21: 1744–1754. doi: 10.1111/j.1420-9101.2008.01587.x
- Issue online: 15 OCT 2008
- Version of Record online: 7 AUG 2008
- Received 11 April 2008; revised 18 June 2008; accepted 21 June 2008
- ecological immunology;
- host–parasite interaction;
- phenotypic plasticity;
Several insect species show an increase in cuticular melanism in response to high densities. In some species, there is evidence that this melanism is correlated with an up-regulation of certain immune system components, particularly phenoloxidase (PO) activity, and with the down-regulation of lysozyme activity, suggesting a trade-off between the two traits. As melanism has a genetic component, we selected both melanic and nonmelanic lines of the phase-polyphenic lepidopteran, Spodoptera littoralis, in order to test for a causative genetic link between melanism, PO activity and lysozyme activity, and to establish if there are any life-history costs associated with the melanic response. We found that, in fact, melanic lines had lower PO activity and higher lysozyme activity than nonmelanic lines, confirming a genetic trade-off between the two immune responses, but also indicating a genetic trade-off between melanism and PO activity. In addition, we found that lines with high PO activity had slower development rates suggesting that investment in PO, rather than in melanism, is costly.