Present address: Institute de Recherche sur la Biologie de l'Insecte, UMR-CNRS 6035, Faculté des Sciences et Techniques, 37200 Tours, France.
Presence of soldier larvae determines the outcome of competition in a polyembryonic wasp
Article first published online: 1 SEP 2006
Journal of Evolutionary Biology
Volume 20, Issue 1, pages 165–172, January 2007
How to Cite
GIRON, D., ROSS, K. G. and STRAND, M. R. (2007), Presence of soldier larvae determines the outcome of competition in a polyembryonic wasp. Journal of Evolutionary Biology, 20: 165–172. doi: 10.1111/j.1420-9101.2006.01212.x
- Issue published online: 18 DEC 2006
- Article first published online: 1 SEP 2006
- Received 11 May 2006; revised 5 July 2006; accepted 12 July 2006
Soldier-producing polyembryonic waSPS are the only social animals that develop as parasites inside the bodies of other insects. Characterizing the kin composition of broods is central to understanding the evolution of the soldier caste in these unique social insects. Here we studied the role of soldiers in mediating the outcome of competition among clones of the polyembryonic wasp Copidosoma floridanum. Soldier-producing female clones usually monopolized host resources, whereas soldierless male clones usually coexisted in hosts. Behavioural experiments further indicated that early-emerging soldiers are specialized to combat intraspecific competitors and later-emerging soldiers are specialized for defence against interspecific competitors. Taken together, our results point to intraspecific competition as a major selective force in the evolution of the soldier caste. Our data also present an evolutionary conundrum: given the benefit of soldiers, why are male clones functionally soldierless?