Female choice reveals terminal investment in male mealworm beetles, Tenebrio molitor, after a repeated activation of the immune system

I Krams1,2a*, J Daukšte2b, I Kivleniece2c, T Krama2d, MJ Rantala1e, G Ramey2f, and L Šauša3g

1Department of Biology, University of Turku, FIN-20024 Turku, Finland
2Institute of Systematic Biology, University of Daugavpils, LV-5401 Daugavpils, Latvia
3Department of Life Sciences, Anglia Ruskin University, Cambridge CB 1PT, UK

Abstract

Increasing evidence suggests that secondary sexual traits reflect immunocompetence of males in many animal species. This study experimentally investigated whether a parasite-like immunological challenge via a nylon implant affects sexual attractiveness of males in Tenebrio molitor L. (Coleoptera: Tenebrionidae) Although a single immunological challenge significantly reduced sexual attractiveness and locomotor activity of males, it had no adverse effect on their survival. A second immune challenge of the same males increased their attractiveness. However, it was found that the repeated challenge significantly reduced locomotor activity of males and caused higher mortality. This result indicates terminal investment on sexual signaling, which is supposedly based on a trade-off between pheromone production and energy expenditures needed for such activities as recovery of immune system and locomotor activity. When the third implantation was carried out in the same group of males, melanization of nylon implants was found to be lower in more attractive than in less attractive males. This suggests that males that became sexually attractive after the second immune challenge did not invest in recovery of their immune system.

Keywords: immune challenge, sexual selection, terminal investment

Correspondence: a* indrikis.krams@biology.lv, b janina.daukste@inbox.lv, c inese.kivleniece@biology.lv, d tatjana.krama@biology.lv, e mjranta@utu.fi, f g.ramey@pobox.com, g liga_sh@yahoo.com, *Corresponding author

Editor: Todd Shelly was editor of this paper

Received: 14 March 2010 | Accepted: 16 January 2011 | Published: 2 May 2011

ISSN: 1536-2442 | Volume 11, Number 56

Krams I, Daukšte J, Kivleniece I, Krama T, Rantala MJ, Ramey G, Šauša L. 2011. Female choice reveals terminal investment in male mealworm beetles, Tenebrio molitor, after a repeated activation of the immune system. Journal of Insect Science 11:56 available online: insectscience.org/11.56


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