Comparing constitutive and induced costs of symbiont-conferred resistance to parasitoids in aphids


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Date

2013-03

Publication Type

Journal Article

ETH Bibliography

yes

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Abstract

Host defenses against parasites do not come for free. The evolution of increased resistance can be constrained by constitutive costs associated with possessing defense mechanisms, and by induced costs of deploying them. These two types of costs are typically considered with respect to resistance as a genetically determined trait, but they may also apply to resistance provided by ‘helpers’ such as bacterial endosymbionts. We investigated the costs of symbiont‐conferred resistance in the black bean aphid, Aphis fabae (Scopoli), which receives strong protection against the parasitoid Lysiphlebus fabarum from the defensive endosymbiont Hamiltonella defensa. Aphids infected with H. defensa were almost ten times more resistant to L. fabarum than genetically identical aphids without this symbiont, but in the absence of parasitoids, they had strongly reduced lifespans, resulting in lower lifetime reproduction. This is evidence for a substantial constitutive cost of harboring H. defensa. We did not observe any induced cost of symbiont‐conferred resistance. On the contrary, symbiont‐protected aphids that resisted a parasitoid attack enjoyed increased longevity and lifetime reproduction compared with unattacked controls, whereas unprotected aphids suffered a reduction of longevity and reproduction after resisting an attack. This surprising result suggests that by focusing exclusively on the protection, we might underestimate the selective advantage of infection with H. defensa in the presence of parasitoids.

Publication status

published

Editor

Book title

Volume

3 (3)

Pages / Article No.

706 - 713

Publisher

Wiley

Event

Edition / version

Methods

Software

Geographic location

Date collected

Date created

Subject

Aphis fabae; Hamiltonella defensa; Lysiphlebus fabarum; Parasitoid; Resistance; Symbiosis

Organisational unit

03838 - Vorburger, Ch. (SNF-Professur) (ehem.) check_circle

Notes

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