Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Sperm storage induces an immunity cost in ants


Ant queens are among the most long-lived insects known1,2. They mate early in adult life and maintain millions of viable sperm in their sperm storage organ until they die many years later3,4. Because they never re-mate, the reproductive success of queens is ultimately sperm-limited, but it is not known what selective forces determine the upper limit to sperm storage. Here we show that sperm storage carries a significant cost of reduced immunity during colony founding. Newly mated queens of the leaf-cutting ant Atta colombica upregulate their immune response shortly after completing their nest burrow, probably as an adaptive response to a greater exposure to pathogens in the absence of grooming workers. However, the immune response nine days after colony founding is negatively correlated with the amount of sperm in the sperm storage organ, indicating that short-term survival is traded off against long-term reproductive success. The immune response was lower when more males contributed to the stored sperm, indicating that there might be an additional cost of mating or storing genetically different ejaculates.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Increase in immune response during colony founding.
Figure 2: Effect of stored sperm on immune response.
Figure 3: Effect of number of mates on immune response.


  1. 1

    Keller, L. & Genoud, M. Extraordinary lifespans in ants: a test of evolutionary theories of ageing. Nature 389, 958–960 (1997)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Pamilo, P. Life span of queens in the ant Formica exsecta. Insect. Soc. 38, 111–120 (1991)

    Article  Google Scholar 

  3. 3

    Wheeler, D. E. & Krutzsch, P. H. Ultrastructure of the spermatheca and its associated gland in the ant Crematogaster opuntiae (Hymenoptera, Formicidae). Zoomorphology 114, 203–212 (1994)

    Article  Google Scholar 

  4. 4

    Hölldobler, B. & Bartz, S. H. in Experimental Behavioural Ecology and Sociobiology (eds Hölldobler, B. & Lindauer, M.) 237–257 (Gustav Fischer, Stuttgart, 1985)

    Google Scholar 

  5. 5

    Birkhead, T. R. & Møller, A. P. Sperm Competition and Sexual Selection (Academic, New York, 1998)

    Google Scholar 

  6. 6

    Eberhard, W. G. Female Control: Sexual Selection by Cryptic Female Choice (Princeton Univ. Press, Princeton, 1996)

    Google Scholar 

  7. 7

    Simmons, L. W. Sperm Competition and its Evolutionary Consequences in the Insects (Princeton Univ. Press, Princeton, 2001)

    Google Scholar 

  8. 8

    Baer, B. Sexual selection in Apis bees. Apidologie (Celle) 36, 187–200 (2005)

    Article  Google Scholar 

  9. 9

    Breque, C., Surai, P. & Brillard, J. P. Roles of antioxidants on prolonged storage of avian spermatozoa in vivo and in vitro. Mol. Reprod. Dev. 66, 314–323 (2003)

    CAS  Article  Google Scholar 

  10. 10

    Boomsma, J. J., Baer, B. & Heinze, J. The evolution of male traits in social insects. Annu. Rev. Entomol. 50, 395–420 (2005)

    CAS  Article  Google Scholar 

  11. 11

    Tschinkel, W. R. & Porter, S. D. Efficiency of sperm use in queens of the fire ant, Solenopsis invicta (Hymenoptera: Formicidae). Ann. Entomol. Soc. Am. 81, 777–781 (1988)

    Article  Google Scholar 

  12. 12

    Crozier, R. H. & Page, R. E. On being the right size: Male contributions and multiple mating in social hymenoptera. Behav. Ecol. Sociobiol. 18, 105–116 (1985)

    Article  Google Scholar 

  13. 13

    Boomsma, J. J., Schmid-Hempel, P. & Hughes, W. O. H. in Insect Evolutionary Ecology (eds Fellowes, M., Holloway, G. & Rolff, J.) 139–175 (CABI, Wallingford, 2005)

    Google Scholar 

  14. 14

    Weber, N. A. Gardening Ants: The Attines (American Philosophical Society, Philadelphia, 1972)

    Google Scholar 

  15. 15

    Fowler, H. G., Pereira da Silva, V., Forti, L. C. & Saes, N. B. in Fire Ants and Leaf Cutting Ants: Biology and Management (eds Lofgren, C. S. & Vander Meer, R. K.) 123–145 (Westview Press, Boulder, Colorado, 1986)

    Google Scholar 

  16. 16

    Baer, B. & Schmid-Hempel, P. Effects of selective episodes in the field on life history traits in the bumblebee Bombus terrestris. Oikos 101, 563–568 (2003)

    Article  Google Scholar 

  17. 17

    Baer, B. & Schmid-Hempel, P. Sperm in fluences female hibernation success, survival and fitness in the bumblebee Bombus terrestris. Proc. R. Soc. B 272, 319–323 (2005)

    Article  Google Scholar 

  18. 18

    Rolff, J. & Siva-Jothy, M. T. Invertebrate ecological immunology. Science 301, 472–475 (2003)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Fjerdingstad, E. J. & Boomsma, J. J. Multiple mating increases the sperm stores of Atta colombica leafcutter ant queens. Behav. Ecol. Sociobiol. 42, 257–261 (1998)

    Article  Google Scholar 

  20. 20

    Hölldobler, B. & Wilson, E. O. The Ants (Springer, Berlin, 1990)

    Book  Google Scholar 

  21. 21

    Tian, H. S., Vinson, S. B. & Coates, C. J. Differential gene expression between alate and dealate queens in the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae). Insect Biochem. Mol. Biol. 34, 937–949 (2004)

    CAS  Article  Google Scholar 

  22. 22

    Fjerdingstad, E. J. & Boomsma, J. J. Variation in size and sperm content of sexuals in the leafcutter ant Atta colombica. Insect. Soc. 44, 209–218 (1997)

    Article  Google Scholar 

  23. 23

    Baer, B. & Boomsma, J. J. Male reproductive investment and queen mating frequency in fungus growing ants. Behav. Ecol. 15, 426–432 (2004)

    Article  Google Scholar 

  24. 24

    Baer, B. & Schmid-Hempel, P. Unexpected consequences of polyandry for parasitism and fitness in the bumblebee, Bombus terrestris. Evolution Int. J. Org. Evolution 55, 1639–1643 (2001)

    CAS  Article  Google Scholar 

  25. 25

    Baer, B. & Schmid Hempel, P. The artificial insemination of bumblebee queens. Insect. Soc. 47, 183–187 (2000)

    Article  Google Scholar 

  26. 26

    Fjerdingstad, E. J., Boomsma, J. J. & Thoren, P. Multiple paternity in the leafcutter ant Atta colombica—a microsatellite DNA study. Heredity 80, 118–126 (1998)

    Article  Google Scholar 

Download references


We thank D. R. Nash for advice on statistical issues; C. Andersen and S. Mathiasen for assistance with DNA work; S. Mathiasen and D. J. C. Kronauer for advice on DNA work; S. P. A. den Boer, M. Poulsen, A. M. Schmidt, J. Thomas and L. V. Ugelvig for assistance in the field, and P. D'Ettorre, D. R. Nash, J. S. Pedersen, B. Baer-Imhoof and L. W. Simmons for comments on the manuscript. This study was supported by the Swiss National Science Foundation (stipend for advanced scientists to B.B.), the EU Research-Training Network INSECTS, the Carlsberg Foundation and a Marie Curie Intra-European Fellowship (postdoctoral stipends to S.A.O.A.), the Danish Natural Science Research Council (B.B. and J.J.B.) and the Danish National Research Foundation (J.J.B. and S.A.O.A.). We thank the Smithsonian Tropical Research Institute in Panama for facilities and logistical support, and the Autoridad Nacional de Ambiente (ANAM) of Panama for issuing collection and export permits.

Author information



Corresponding author

Correspondence to Boris Baer.

Ethics declarations

Competing interests

Reprints and permissions information is available at The authors declare no competing financial interests.

Supplementary information

Supplementary Notes

This file contains further information about the methodology used for the study, as well as additional data supporting the main manuscript. (DOC 75 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Baer, B., Armitage, S. & Boomsma, J. Sperm storage induces an immunity cost in ants. Nature 441, 872–875 (2006).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing