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Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes

Cooperative secretion of virulence factors by pathogens can lead to social conflict when cheating mutants exploit collective secretion, but do not contribute to it. If cheats outcompete cooperators within hosts, this can cause loss of virulence. Insect parasitic nematodes are important biocontrol to...

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Autores principales: Shapiro‐Ilan, David, Raymond, Ben
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4778107/
https://www.ncbi.nlm.nih.gov/pubmed/26989437
http://dx.doi.org/10.1111/eva.12348
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author Shapiro‐Ilan, David
Raymond, Ben
author_facet Shapiro‐Ilan, David
Raymond, Ben
author_sort Shapiro‐Ilan, David
collection PubMed
description Cooperative secretion of virulence factors by pathogens can lead to social conflict when cheating mutants exploit collective secretion, but do not contribute to it. If cheats outcompete cooperators within hosts, this can cause loss of virulence. Insect parasitic nematodes are important biocontrol tools that secrete a range of significant virulence factors. Critically, effective nematodes are hard to maintain without live passage, which can lead to virulence attenuation. Using experimental evolution, we tested whether social cheating might explain unstable virulence in the nematode Heterorhabditis floridensis by manipulating relatedness via multiplicity of infection (MOI), and the scale of competition. Passage at high MOI, which should reduce relatedness, led to loss of fitness: virulence and reproductive rate declined together and all eight independent lines suffered premature extinction. As theory predicts, relatedness treatments had more impact under stronger global competition. In contrast, low MOI passage led to more stable virulence and increased reproduction. Moreover, low MOI lineages showed a trade‐off between virulence and reproduction, particularly for lines under stronger between‐host competition. Overall, this study indicates that evolution of virulence theory is valuable for the culture of biocontrol agents: effective nematodes can be improved and maintained if passage methods mitigate possible social conflicts.
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spelling pubmed-47781072016-03-17 Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes Shapiro‐Ilan, David Raymond, Ben Evol Appl Original Articles Cooperative secretion of virulence factors by pathogens can lead to social conflict when cheating mutants exploit collective secretion, but do not contribute to it. If cheats outcompete cooperators within hosts, this can cause loss of virulence. Insect parasitic nematodes are important biocontrol tools that secrete a range of significant virulence factors. Critically, effective nematodes are hard to maintain without live passage, which can lead to virulence attenuation. Using experimental evolution, we tested whether social cheating might explain unstable virulence in the nematode Heterorhabditis floridensis by manipulating relatedness via multiplicity of infection (MOI), and the scale of competition. Passage at high MOI, which should reduce relatedness, led to loss of fitness: virulence and reproductive rate declined together and all eight independent lines suffered premature extinction. As theory predicts, relatedness treatments had more impact under stronger global competition. In contrast, low MOI passage led to more stable virulence and increased reproduction. Moreover, low MOI lineages showed a trade‐off between virulence and reproduction, particularly for lines under stronger between‐host competition. Overall, this study indicates that evolution of virulence theory is valuable for the culture of biocontrol agents: effective nematodes can be improved and maintained if passage methods mitigate possible social conflicts. John Wiley and Sons Inc. 2016-01-27 /pmc/articles/PMC4778107/ /pubmed/26989437 http://dx.doi.org/10.1111/eva.12348 Text en © 2015 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution (http://creativecommons.org/licenses/by/4.0/) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Articles
Shapiro‐Ilan, David
Raymond, Ben
Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
title Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
title_full Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
title_fullStr Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
title_full_unstemmed Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
title_short Limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
title_sort limiting opportunities for cheating stabilizes virulence in insect parasitic nematodes
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4778107/
https://www.ncbi.nlm.nih.gov/pubmed/26989437
http://dx.doi.org/10.1111/eva.12348
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