Parasitology

Research Article

Competitive exclusion in human schistosomes: the restricted distribution of Schistosoma intercalatum

L. A. Tchuem Tchuentéa1a2a3, S. Moranda1, D. Imbert-Estableta1, B. Delaya4 and J. Jourdanea1 c1

a1 Laboratoire de Biologie Animate (URA CNRS 698), Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Université, Avenue de Villeneuve, 66860 Perpignan Cedex, France

a2 Laboratoire de Biologie Générale, Faculté des Sciences, Université de Yaoundé I, B.P. 812 Yaoundé, Cameroun

a3 Department of Zoology, The Natural History Museum, Cromwell Road, South Kensingston, London, UK

a4 Laboratoire de Génétique et Environnement, Institut des Sciences de l'Evolution, Université de Montpellier II, place E. Bataillon, 34095 Monpellier Cedex 5, France

SUMMARY

A study on the immune and mating interactions between Schistosoma intercalatum and S. mansoni has been carried out. The immunologically mediated interactions and mating patterns observed between the two species demonstrate that S. mansoni is competitively dominant over S. intercalatum. When S. mansoni females are absent, S. mansoni males are more competitive than S. intercalatum males at pairing with S. intercalatum females. The use of a mathematical model shows how the abundance of S. mansoni worms per host could dramatically affect the mating probability of S. intercalatum females with their homologous males. It appears that the competitive exclusion between these two species of schistosomes may probably be an important factor restricting the distribution of S. intercalatum in Africa.

(Received October 18 1995)

(Revised January 12 1996)

(Revised February 12 1996)

(Accepted February 12 1996)

Correspondence:

c1 Corresponding author. Laboratoire de Biologie Animale, Centre de Biologie et d'Ecologie Tropicale et Méditerranéenne, Université, Avenue de Villeneuve, 66860 Perpignan Cedex, France. Tel: +33 68 66 21 82. Fax: + 33 68 66 22 81. E-mail: jourdane@univ-perp.fr.

Metrics