title: A survival-reproduction trade-off in entomopathogenic nematodes mediated by their bacterial symbionts.
abstract: In this work, we investigate the investment of entomopathogenic Steinernema nematodes (Rhabditidae) in their symbiotic association with Xenorhabdus bacteria (Enterobacteriaceae). Their life cycle comprises two phases: (1) a free stage in the soil, where infective juveniles (IJs) of the nematode carry bacteria in a digestive vesicle and search for insect hosts, and (2) a parasitic stage into the insect where bacterial multiplication, nematode reproduction, and production of new IJs occur. Previous studies clearly showed benefits to the association for the nematode during the parasitic stage, but preliminary data suggest the existence of costs to the association for the nematode in free stage. IJs deprived from their bacteria indeed survive longer than symbiotic ones. Here we show that those bacteria-linked costs and benefits lead to a trade-off between fitness traits of the symbiotic nematodes. Indeed IJs mortality positively correlates with their parasitic success in the insect host for symbiotic IJs and not for aposymbiotic ones. Moreover mortality and parasitic success both positively correlate with the number of bacteria carried per IJ, indicating that the trade-off is induced by symbiosis. Finally, the trade-off intensity depends on parental effects and, more generally, is greater under restrictive environmental conditions.
authors.affiliation: Institut des Sciences de l'Evolution de Montpellier, c.c. 63 CNRS-UM2 UMR 5554, Université de Montpellier 2, Place Eugène Bataillon, 34095 Cedex 05 Montpellier, France. vanya.emelianoff@univ-montp2.fr
authors.forename: Vanya
authors.initials: V
authors.lastname: Emelianoff
authors.forename: Elodie
authors.initials: E
authors.lastname: Chapuis
authors.forename: Nathalie
authors.initials: N
authors.lastname: Le Brun
authors.forename: Magali
authors.initials: M
authors.lastname: Chiral
authors.forename: Catherine
authors.initials: C
authors.lastname: Moulia
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Ferdy
mesh_terms: D000818:Animals; D006790:Host-Parasite Interactions / Q000502:physiology*; D016014:Linear Models; D009036:Moths / Q000469:parasitology*; D012098:Reproduction / Q000502:physiology; D017168:Rhabditida / Q000382:microbiology* / Q000502:physiology; D013559:Symbiosis / Q000502:physiology*; D020593:Xenorhabdus / Q000502:physiology*