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Conditional Reduction of Predation Risk Associated with a Facultative Symbiont in an Insect.

Polin S, Le Gallic JF, Simon JC, Tsuchida T, Outreman Y - PLoS ONE (2015)

Bottom Line: As body colour affects the susceptibility towards natural enemies in aphids, the influence of the colour change due to these facultative symbionts on the host survival in presence of predators was tested.Due to results from uninfected aphids (i.e., more green ones attacked), the main assumption is that this symbiotic infection would deter the predatory ladybird feeding by reducing the profitability of their hosts rather than decreasing host detection through body colour change.The underlying mechanisms and ecological consequences of these symbiotic effects are discussed.

View Article: PubMed Central - PubMed

Affiliation: UMR 1349 IGEPP, Agrocampus Ouest, 35042, Rennes, France.

ABSTRACT
Symbionts are widespread among eukaryotes and their impacts on the ecology and evolution of their hosts are meaningful. Most insects harbour obligate and facultative symbiotic bacteria that can influence their phenotype. In the pea aphid Acyrthosiphon pisum, an astounding symbiotic-mediated phenotype has been recently observed: when infected with the symbiotic bacteria Rickettsiella viridis, young red aphid larvae become greener at adulthood and even darker green when co-infected with Rickettsiella viridis and Hamiltonella defensa. As body colour affects the susceptibility towards natural enemies in aphids, the influence of the colour change due to these facultative symbionts on the host survival in presence of predators was tested. Our results suggested that the Rickettsiella viridis infection may impact positively host survival by reducing predation risk. Due to results from uninfected aphids (i.e., more green ones attacked), the main assumption is that this symbiotic infection would deter the predatory ladybird feeding by reducing the profitability of their hosts rather than decreasing host detection through body colour change. Aphids co-infected with Rickettsiella viridis and Hamiltonella defensa were, however, more exposed to predation suggesting an ecological cost associated with multiple infections. The underlying mechanisms and ecological consequences of these symbiotic effects are discussed.

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Related in: MedlinePlus

The overall rate of aphid survival.Proportion of surviving Acyrthosiphon pisum aphids among the thirty exposed to predation by an adult Coccinella septempunctata during 24 hours. Each treatment is the combination of two aphid types exposed to predation. See Fig 1 for the treatment code. Twenty replicates have been conducted per treatment (except for treatment GBR-GBRH where N = 16). Error bars represent the standard error of the proportion. Different letters presents significant difference (p < 0.05; GLMM).
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pone.0143728.g002: The overall rate of aphid survival.Proportion of surviving Acyrthosiphon pisum aphids among the thirty exposed to predation by an adult Coccinella septempunctata during 24 hours. Each treatment is the combination of two aphid types exposed to predation. See Fig 1 for the treatment code. Twenty replicates have been conducted per treatment (except for treatment GBR-GBRH where N = 16). Error bars represent the standard error of the proportion. Different letters presents significant difference (p < 0.05; GLMM).

Mentions: According to the first analysis, the overall rate of aphid survival when exposed to ladybird predation varied among the six experimental treatments (χ2 = 15.89; df = 5; p = 0.007; Fig 2). The level of ladybird consumption was lowest when we combined aphid individuals infected with Rickettsiella and aphid individuals co-infected with both facultative symbionts (overall rate of aphid survival: 0.70±0.04). Inversely, the rate of predation was significantly highest when predators were exposed to aphids free of facultative symbionts (overall rate of aphid survival: 0.51±0.03). Globally, the overall rate of aphid survival was highest in the three experimental treatments including individuals harbouring Rickettsiella singly (Fig 2) whatever the colour of the aphids exposed to ladybird predators.


Conditional Reduction of Predation Risk Associated with a Facultative Symbiont in an Insect.

Polin S, Le Gallic JF, Simon JC, Tsuchida T, Outreman Y - PLoS ONE (2015)

The overall rate of aphid survival.Proportion of surviving Acyrthosiphon pisum aphids among the thirty exposed to predation by an adult Coccinella septempunctata during 24 hours. Each treatment is the combination of two aphid types exposed to predation. See Fig 1 for the treatment code. Twenty replicates have been conducted per treatment (except for treatment GBR-GBRH where N = 16). Error bars represent the standard error of the proportion. Different letters presents significant difference (p < 0.05; GLMM).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664394&req=5

pone.0143728.g002: The overall rate of aphid survival.Proportion of surviving Acyrthosiphon pisum aphids among the thirty exposed to predation by an adult Coccinella septempunctata during 24 hours. Each treatment is the combination of two aphid types exposed to predation. See Fig 1 for the treatment code. Twenty replicates have been conducted per treatment (except for treatment GBR-GBRH where N = 16). Error bars represent the standard error of the proportion. Different letters presents significant difference (p < 0.05; GLMM).
Mentions: According to the first analysis, the overall rate of aphid survival when exposed to ladybird predation varied among the six experimental treatments (χ2 = 15.89; df = 5; p = 0.007; Fig 2). The level of ladybird consumption was lowest when we combined aphid individuals infected with Rickettsiella and aphid individuals co-infected with both facultative symbionts (overall rate of aphid survival: 0.70±0.04). Inversely, the rate of predation was significantly highest when predators were exposed to aphids free of facultative symbionts (overall rate of aphid survival: 0.51±0.03). Globally, the overall rate of aphid survival was highest in the three experimental treatments including individuals harbouring Rickettsiella singly (Fig 2) whatever the colour of the aphids exposed to ladybird predators.

Bottom Line: As body colour affects the susceptibility towards natural enemies in aphids, the influence of the colour change due to these facultative symbionts on the host survival in presence of predators was tested.Due to results from uninfected aphids (i.e., more green ones attacked), the main assumption is that this symbiotic infection would deter the predatory ladybird feeding by reducing the profitability of their hosts rather than decreasing host detection through body colour change.The underlying mechanisms and ecological consequences of these symbiotic effects are discussed.

View Article: PubMed Central - PubMed

Affiliation: UMR 1349 IGEPP, Agrocampus Ouest, 35042, Rennes, France.

ABSTRACT
Symbionts are widespread among eukaryotes and their impacts on the ecology and evolution of their hosts are meaningful. Most insects harbour obligate and facultative symbiotic bacteria that can influence their phenotype. In the pea aphid Acyrthosiphon pisum, an astounding symbiotic-mediated phenotype has been recently observed: when infected with the symbiotic bacteria Rickettsiella viridis, young red aphid larvae become greener at adulthood and even darker green when co-infected with Rickettsiella viridis and Hamiltonella defensa. As body colour affects the susceptibility towards natural enemies in aphids, the influence of the colour change due to these facultative symbionts on the host survival in presence of predators was tested. Our results suggested that the Rickettsiella viridis infection may impact positively host survival by reducing predation risk. Due to results from uninfected aphids (i.e., more green ones attacked), the main assumption is that this symbiotic infection would deter the predatory ladybird feeding by reducing the profitability of their hosts rather than decreasing host detection through body colour change. Aphids co-infected with Rickettsiella viridis and Hamiltonella defensa were, however, more exposed to predation suggesting an ecological cost associated with multiple infections. The underlying mechanisms and ecological consequences of these symbiotic effects are discussed.

Show MeSH
Related in: MedlinePlus