, Volume 153, Issue 2, pp 323–329 | Cite as

Genetic variation in the effect of a facultative symbiont on host-plant use by pea aphids

  • Julia FerrariEmail author
  • Claire L. Scarborough
  • H. Charles J. Godfray
Plant Animal Interactions


Ecological specialisation on different host plants occurs frequently among phytophagous insects and is normally assumed to have a genetic basis. However, insects often carry microbial symbionts, which may play a role in the evolution of specialisation. The bacterium Regiella insecticola is a facultative symbiont of pea aphids (Acyrthosiphon pisum) where it is found most frequently in aphid clones feeding on Trifolium giving rise to the hypothesis that it may improve aphid performance on this plant. A study in which R. insecticola was eliminated from a single naturally infected aphid clone supported the hypothesis, but a second involving two aphid clones did not find the same effect. We created a series of new pea aphid–R. insecticola associations by injecting different strains of bacteria into five aphid clones uninfected by symbionts. For all aphid clones, the bacteria decreased the rate at which aphids accepted Vicia faba as a food plant and reduced performance on this plant. Their effect on aphids given Trifolium pratense was more complex: R. insecticola negatively affected acceptance by all aphid clones, had no effect on the performance of four aphid clones, but increased performance of a fifth, thus demonstrating genetic variation in the effect of R. insecticola on pea aphid host use. We discuss how these results may explain the distribution and frequency of this symbiont across different aphid populations.


Acyrthosiphon pisum Host-plant specialisation Regiella insecticola Secondary symbiont Trifolium pratense 



C. L. S. was supported by a NERC studentship. Our work complied with UK law.


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Julia Ferrari
    • 1
    • 2
    Email author
  • Claire L. Scarborough
    • 1
  • H. Charles J. Godfray
    • 1
    • 2
  1. 1.NERC Centre for Population Biology and Division of BiologyImperial College LondonAscotUK
  2. 2.Department of ZoologyUniversity of OxfordOxfordUK

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