Selection for cuticular melanism reveals immune function and life-history trade-offs in Spodoptera littoralis

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 . pp. 1744-1754.

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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.

Keywords:ecological immunology, host–parasite interaction, insect, Lepidoptera, lysozyme, melanism, phenoloxidase, phenotypic plasticity, selection, trade-offs.
Subjects:C Biological Sciences > C550 Immunology
C Biological Sciences > C360 Pest Science
C Biological Sciences > C111 Parasitology
C Biological Sciences > C182 Evolution
C Biological Sciences > C150 Environmental Biology
C Biological Sciences > C340 Entomology
C Biological Sciences > C120 Behavioural Biology
C Biological Sciences > C180 Ecology
C Biological Sciences > C300 Zoology
C Biological Sciences > C100 Biology
Divisions:College of Science > School of Life Sciences
ID Code:16012
Deposited On:16 Nov 2014 20:40

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