Aphid reproductive investment in response to mortality risks

<p>Abstract</p> <p>Background</p> <p>Aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. Perhaps as a resu...

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Main Authors: Barribeau Seth M, Sok Daniel, Gerardo Nicole M
Format: Article
Language:English
Published: BMC 2010-08-01
Series:BMC Evolutionary Biology
Online Access:http://www.biomedcentral.com/1471-2148/10/251
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spelling doaj-fcd6198d9d8b43d0acbbfbc506c2b4ad2021-09-02T10:39:25ZengBMCBMC Evolutionary Biology1471-21482010-08-0110125110.1186/1471-2148-10-251Aphid reproductive investment in response to mortality risksBarribeau Seth MSok DanielGerardo Nicole M<p>Abstract</p> <p>Background</p> <p>Aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. Perhaps as a result of this bacterial dependence, aphids have limited immune function that may leave them vulnerable to bacterial pathogens. An alternative, non-immunological response that may be available to infected aphids is to increase reproduction, thereby ameliorating fitness loss from infection. Such a response would reduce the need to mount a potentially energetically costly immune response, and would parallel that of other hosts that alter life-history traits when there is a risk of infection. Here we examined whether pea aphids (<it>Acyrthosiphon pisum</it>) respond to immunological challenges by increasing reproduction. As a comparison to the response to the internal cue of risk elicited by immunological challenge, we also exposed pea aphids to an external cue of risk - the aphid alarm pheromone (<it>E</it>)-<it>β</it>-farnesene (EBF), which is released in the presence of predators. For each challenge, we also examined whether the presence of symbionts modified the host response, as maintaining host fitness in the face of challenge would benefit both the host and its dependent bacteria.</p> <p>Results</p> <p>We found that aphids stabbed abdominally with a sterile needle had reduced fecundity relative to control aphids but that aphids stabbed with a needle bearing heat-killed bacteria had reproduction intermediate, and statistically indistinguishable, to the aphids stabbed with a sterile needle and the controls. Aphids with different species of facultative symbiotic bacteria had different reproductive patterns overall, but symbionts in general did not alter aphid reproduction in response to bacterial exposure. However, in response to exposure to alarm pheromone, aphids with <it>Hamiltonella defensa </it>or <it>Serratia symbiotica </it>symbiotic infections increased reproduction but those without a facultative symbiont or with <it>Regiella insecticola </it>did not.</p> <p>Conclusions</p> <p>Overall, our results suggest that pea aphids are able to increase their reproduction in response to specific cues and that symbiont presence sometimes moderates this response. Such increased reproduction in response to risk of death increases the fitness of both aphids and their vertically transmitted symbionts, and since these organisms have high reproductive capacity, slight increases in reproduction could lead to a very large numerical advantage later in the season. Thus both symbiotic partners can benefit by increasing host fecundity under dangerous conditions.</p> http://www.biomedcentral.com/1471-2148/10/251
collection DOAJ
language English
format Article
sources DOAJ
author Barribeau Seth M
Sok Daniel
Gerardo Nicole M
spellingShingle Barribeau Seth M
Sok Daniel
Gerardo Nicole M
Aphid reproductive investment in response to mortality risks
BMC Evolutionary Biology
author_facet Barribeau Seth M
Sok Daniel
Gerardo Nicole M
author_sort Barribeau Seth M
title Aphid reproductive investment in response to mortality risks
title_short Aphid reproductive investment in response to mortality risks
title_full Aphid reproductive investment in response to mortality risks
title_fullStr Aphid reproductive investment in response to mortality risks
title_full_unstemmed Aphid reproductive investment in response to mortality risks
title_sort aphid reproductive investment in response to mortality risks
publisher BMC
series BMC Evolutionary Biology
issn 1471-2148
publishDate 2010-08-01
description <p>Abstract</p> <p>Background</p> <p>Aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. Perhaps as a result of this bacterial dependence, aphids have limited immune function that may leave them vulnerable to bacterial pathogens. An alternative, non-immunological response that may be available to infected aphids is to increase reproduction, thereby ameliorating fitness loss from infection. Such a response would reduce the need to mount a potentially energetically costly immune response, and would parallel that of other hosts that alter life-history traits when there is a risk of infection. Here we examined whether pea aphids (<it>Acyrthosiphon pisum</it>) respond to immunological challenges by increasing reproduction. As a comparison to the response to the internal cue of risk elicited by immunological challenge, we also exposed pea aphids to an external cue of risk - the aphid alarm pheromone (<it>E</it>)-<it>β</it>-farnesene (EBF), which is released in the presence of predators. For each challenge, we also examined whether the presence of symbionts modified the host response, as maintaining host fitness in the face of challenge would benefit both the host and its dependent bacteria.</p> <p>Results</p> <p>We found that aphids stabbed abdominally with a sterile needle had reduced fecundity relative to control aphids but that aphids stabbed with a needle bearing heat-killed bacteria had reproduction intermediate, and statistically indistinguishable, to the aphids stabbed with a sterile needle and the controls. Aphids with different species of facultative symbiotic bacteria had different reproductive patterns overall, but symbionts in general did not alter aphid reproduction in response to bacterial exposure. However, in response to exposure to alarm pheromone, aphids with <it>Hamiltonella defensa </it>or <it>Serratia symbiotica </it>symbiotic infections increased reproduction but those without a facultative symbiont or with <it>Regiella insecticola </it>did not.</p> <p>Conclusions</p> <p>Overall, our results suggest that pea aphids are able to increase their reproduction in response to specific cues and that symbiont presence sometimes moderates this response. Such increased reproduction in response to risk of death increases the fitness of both aphids and their vertically transmitted symbionts, and since these organisms have high reproductive capacity, slight increases in reproduction could lead to a very large numerical advantage later in the season. Thus both symbiotic partners can benefit by increasing host fecundity under dangerous conditions.</p>
url http://www.biomedcentral.com/1471-2148/10/251
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