Horizontal transfer of facultative endosymbionts is limited by host relatedness.
Heritable microbial symbionts can have important effects on many aspects of their hosts' biology. Acquisition of a novel symbiont strain can provide fitness benefits to the host, with significant ecological and evolutionary consequences. We measured barriers to horizontal transmission by artificially transferring facultative symbionts from the grain aphid, Sitobion avenae, and five other aphid species into two clonal genotypes of S. avenae. We found the symbiont Hamiltonella defensa establishes infections more easily following a transfer from the same host species and that such infections are more stable. Infection success was also higher when the introduced symbiont strain was more closely related to the strain that was originally present in the host (but which had previously been removed). There were no differences among successfully established symbiont strains in their effect on aphid fecundity. Hamiltonella defensa did not confer protection against parasitoids in our S. avenae clones, although it often does in other aphid hosts. However, strains of the symbiont Regiella insecticola originating from two host species protected grain aphids against the pathogenic fungus Pandora neoaphidis. This study helps describe the extent to which facultative symbionts can act as a pool of adaptations that can be sampled by their eukaryote hosts.
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom. p.lukasik@gmail.com.
Piotr
P
Łukasik
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom.|Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Zhongling Street, Nanjing, 210014, China.
Huifang
H
Guo
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom.
Margriet
M
van Asch
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom.
Lee M
LM
Henry
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom.
H Charles J
HC
Godfray
Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, United Kingdom.|Department of Biology, University of York, York, YO10 5DD, United Kingdom.
Julia
J
Ferrari
D000818:Animals; D001042:Aphids / Q000235:genetics / Q000382:microbiology* / Q000469:parasitology; D004755:Enterobacteriaceae / Q000235:genetics / Q000502:physiology; D005298:Fertility; D005658:Fungi / Q000472:pathogenicity; D005838:Genotype; D054884:Host-Pathogen Interactions; D013559:Symbiosis; D014863:Wasps
Acyrthosiphon pisum; Aphidius ervi; Hamiltonella defensa; Pandora neoaphidis; Regiella insecticola; horizontal transfer; invasion; symbiosis