Obligate symbioses between specialized arboreal ants and plants have evolved independently in many lineages1,2. Ant-plants (myrmecophytes) typically provide hollow nest cavities and nutrition to the occupying ant colony1,3,4,5,6. In turn, resident plant-ants often protect their hosts from herbivory7,8,9,10,11 and/or overgrowth by surrounding vegetation12,13. As individual plants are rarely occupied by more than one ant colony14,15,16,17, co-occurring plant-ant species compete intensely for hosts13,14,18,19. In such multi-species systems, ecological interactions among potential partners may lead to the evolution of cheating20,21. Previous studies have revealed that some specialized plant-ants are effectively parasites of their host-plants8,18,22,23, but the selection pressures favouring such behaviours are poorly understood. Here we describe host parasitism in an east African plant-ant that prunes and sterilizes its host-tree canopies, apparently to minimize contact with competitively dominant ants occupying neighbouring trees. We propose that the high density of ant-trees and low diversity of tree species in this savanna habitat have selected for induced, parasitic pruning of host trees by this competitively subordinate ant species.
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
Davidson,D. W. & McKey,D. The evolutionary ecology of symbiotic ant–plant relationships. J. Hymenop. Res. 2, 13–83 (1993).
McKey,D. & Davidson,D. W. in Biological Relationships between Africa and South America; 37th Annual Systematics Symposium, St. Louis, Missouri, USA, October 4–6, 1990 (ed. Goldblatt, P.) 568–606 (Yale Univ. Press, New Haven, New Haven, 1993).
Bentley,B. L. Extrafloral nectaries and protection by pugnacious bodyguards. Ann. Rev. Ecol. Syst. 8, 407–427 (1977).
Janzen,D. H. Coevolution of mutualism between ants and acacias in Central America. Evolution 20, 249–275 (1966).
Fiala,B. & Maschwitz,U. Food bodies and their significance for obligate ant-association in the tree genus Macaranga (Euphorbiaceae). Botan. J. Linnean Soc. 110, 61–75 (1992).
Risch,S. J. & Rickson,F. R. Mutualism in which ants must be present before plants produce food bodies. Nature 291, 149–150 (1981).
Fonseca,C. R. Herbivory and the long-lived leaves of an Amazonian ant-tree. J. Ecol. 82, 833–842 (1994).
Koptur,S. Experimental evidence for defense of Inga (Mimosoideae) saplings by ants. Ecology 65, 1787–1793 (1994).
Vasconcelos,H. L. Mutualism between Maieta guianesis Aubl., a myrmecophytic melastome, and one of its ant inhabitants: Ant protection against insect herbivores. Oecologia 87, 295–298 (1991).
Madden,D. & Young,T. P. Symbiotic ants as an alternative defense against giraffe herbivory in spinescent Acacia drepanolobium. Oecologica 91, 235–238 (1992).
Stapley,L. The interaction of thorns and symbiotic ants as an effective defence mechanism of swollen-thorn acacias. Oecologica 115, 401–405 (1998).
Janzen,D. H. Allelopathy by myrmecophytes: the ant Azteca as an allelopathic agent of Cecropia. Ecology 50, 147–153 (1969).
Davidson,D. W. & McKey,D. Ant plant symbioses: stalking the Chuyachaqui. Trends Ecol. Evol. 8, 326–332 (1993).
Davidson,D. W., Snelling,R. R. & Longino,J. T. Competition among ants for myrmecophytes and the significance of plant trichomes. Biotropica 21, 64–73 (1989).
Rico-Gray,V. & Thien,L. B. Effect of different ant species on reproductive fitness of Schomburgkia tibicinis (Orchidaceae). Oecologia 81, 487–489 (1989).
Vasconcelos,H. L. Ant colonization of Maieta guianensis seedlings, an Amazon ant-plant. Oecologia 95, 439–443 (1993).
Yu,D. W. & Davidson,D. W. Experimental studies of species-specificity in Cecropia–ant relationships. Ecol. Monogr. 67, 273–294 (1997).
Janzen,D. H. Pseudomyrmex nigripilosa: a parasite of a mutualism. Science 188, 936–937 (1975).
Davidson,D. W., Longino,J. T. & Snelling,R. R. Pruning of host plant neighbors by ants: An experimental approach. Ecology 69, 801–808 (1988).
Pellmyr,O., Leebens-Mack,J. & Huth,C. J. Non-mutualistic yucca moths and their evolutionary consequences. Nature 380, 155–156 (1996).
Bull,J. J. & Rice,W. R. Distinguishing mechanisms for the evolution of cooperation. J. Theor. Biol. 149, 63–74 (1991).
Fiala,B., Grunsky,H., Maschwitz,U. & Linsenmair,K. E. Diversity of ant–plant interactions: Protective efficacy in Macaranga species with different degrees of ant association. Oecologia 97, 186–192 (1994).
Yu,D. W. & Pierce,N. E. A castration parasite of an ant-plant mutualism. Proc. R. Soc. Lond. B 265, 275–282 (1998).
Coe,M. J. & Beentje,H. A Field Guide to the Acacias of Kenya (Oxford Univ. Press, Oxford, 1991).
Young,T. P., Stubblefield,C. H. & Isbell,L. A. Ants on swollen-thorn acacias: Species coexistence in a simple system. Oecologia 109, 98–107 (1997).
Hocking,B. Insect associations with the swollen thorn acacias. Trans. R. Entomol. Soc. Lond. 122, 211–255 (1970).
Wood,W. F. & Chong,B. Alarm pheremones of the east African acacia symbionts: Crematogaster mimosae and C. negriceps. J. Georgia Entomol. Soc. 10, 332–334 (1975).
Janzen,D. H. Interaction of the Bull's-Horn Acacia (Acacia cornigera L.) with an ant inhabitant (Pseudomyrmex ferruginea F. Smith) in Eastern Mexico. Univ. Kansas Sci. Bull. 6, 315–558 (1967).
Freund,R. J., Littel,R. C. & Spector,P. C. SAS System for Linear Models (SAS Institute, Cary, North Carolina, 1986).
We thank J. Lemboi, L. King, F. Lorugoi and F. Frei for field assistance, and the staff of Mpala Research Centre and Segera Ranch for logistical support. Mpala Ranch and Segera Ranch granted access to field sites. This research was supported by the National Science Foundation and by the Bridge Grant program at the University of California at Davis.
About this article
Cite this article
Stanton, M., Palmer, T., Young, T. et al. Sterilization and canopy modification of a swollen thorn acacia tree by a plant-ant. Nature 401, 578–581 (1999). https://doi.org/10.1038/44119
Population Genomics and Demographic Sampling of the Ant-Plant Vachellia drepanolobium and Its Symbiotic Ants From Sites Across Its Range in East Africa
Frontiers in Ecology and Evolution (2019)
Frontiers in Plant Science (2018)
Figs, pollinators, and parasites: A longitudinal study of the effects of nematode infection on fig wasp fitness
Acta Oecologica (2018)