Dynamics of coupled mutualistic and antagonistic ... - ART-Dijon
How do densities vary with perturbation by insecticides ? How does the perturbation regime affect the stability of the system (i.e. resilience sensu McCann, 2000) ...
Dynamics of coupled mutualistic and antagonistic interactions, and their implications for ecosystem management
Ewen Georgelin and Nicolas Loeuille
Interaction networks in agriculture. Dijon | September 2012
Introduction : Pollination and pest control services
Ecological context Pest control : non selective insecticides Potts et al., 2010
Environmental and health costs Van der Werf, 1996
Ecological costs : Pollination service Potts et al., 2010 ; Beismeijer et al., 2006
Sustainable agriculture How to limit pest damages ?
How to enhance pollination service ?
Introduction : Pollination and pest control services
Sustainable agriculture How to limit pest damages ? Bianchi et al., 2006
How to enhance pollination service ? Kearns et al., 1998 ; Klein et al., 2007 ; Potts et al., 2010
Two coexisting and coevolving systems ! Strauss et al., 2004
Introduction : Pollination and pest control services
Each species influences the dynamics of the other Herrera et al., 2002 ; Strauss et al., 2004
Emergence of indirect effects through the plants Strauss, 1992 ; Wootton, 1994 ; Strauss et al., 2004
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Introduction : antagonistic and mutualistic interactions
How are antagonistic and mutualistic interactions coupled in plants-insects systems What are the indirect effects between herbivore and pollinator ?
How does the community respond to perturbation by insecticides ?
The ecological model
3 species model
Perturbation express across two gradients - Additional mortality due to insecticides use: intensity of perturbation - Sensitivity of pollinator to perturbation
The ecological model
Ecological model
The ecological model
Ecological model
Generalist plant and pollinator Specialist herbivore
The ecological model
Ecological model
Type II functional responses
The ecological model
Ecological model
Herbivore death rate
The ecological model
Ecological model
Two perturbation parameters
Questions and hypotheses
Questions : How does the extinction order depend on the sensitivity of pollinator ? How do densities vary with perturbation by insecticides ? How does the perturbation regime affect the stability of the system (i.e. resilience sensu McCann, 2000) ? Hypotheses : Pollinator helps the community in the face of perturbation... ...depending on the sensitivity !
Results
Mathematical analysis : One coexistence equilibrium point
Extinction limits of pollinators and herbivores can be computed : Extinction order First derivatives of equilibrium equations regarding to changes in perturbation parameters computed too : Variations of densities
Results
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Extinction order
Results
1
Extinction order
Results
1
Extinction order
Limit in sensitivity: intersection of curves
Results
1
Extinction order
Behind sensitivity limit: pollinator then herbivore
Results
1
Extinction order
Below sensitivity limit: herbivore then pollinator
Results
1
Extinction order
Limit in sensitivity: lower
Results
1
Extinction order
Same extinction orders
Results
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Extinction order
Pollinator delays extinction of herbivore
Results
2
Density responses to perturbation
Weak sensitivity scenario High sensitivity scenario
Results
2
Density responses to perturbation
Weak sensitivity
High sensitivity
Results
2
Density responses to perturbation
Weak sensitivity
Results
2
Density responses to perturbation : indirect effects
Results
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Density responses to perturbation : indirect effects
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