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The Insect Galleria mellonella as a Powerful Infection Model to Investigate Bacterial Pathogenesis
Published on: December 11, 2012
Host-pathogen interactions, insect outbreaks, and natural selection for disease resistance
Bret D Elderd1, Jonathan Dushoff, Greg Dwyer
1Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA.
The American Naturalist
|November 4, 2008
Summary
Insect population dynamics are stabilized by natural enemy attack rate heterogeneity. However, gypsy moth pathogen infection risk data suggest natural selection drives cycles, explaining outbreaks.
Area of Science:
- Ecology
- Entomology
- Population Dynamics
Background:
- Insect population dynamics theory posits that natural enemy attack rate heterogeneity stabilizes populations.
- Outbreaking insects are often affected by infectious pathogens, necessitating investigation into pathogen attack rates.
Purpose of the Study:
- To test the applicability of insect population dynamics theory to outbreaking insects, specifically gypsy moths.
- To investigate the role of heterogeneity in pathogen attack rates (infection risk) in gypsy moth population dynamics.
Main Methods:
- Measured heterogeneity in nucleopolyhedrovirus infection risk among gypsy moth larvae.
- Developed a new model incorporating natural selection's influence on infection risk fluctuations.
- Conducted experiments to confirm the heritability of infection risk.
Main Results:
- High heterogeneity in gypsy moth infection risk led to model predictions of stable equilibrium, contradicting observed outbreaks.
- Infection risk was observed to decline post-epidemic, challenging the assumption of constant infection risk.
- The alternative model, including natural selection for resistance and its costs, demonstrated cyclical population dynamics.
Conclusions:
- Natural selection driving fluctuations in pathogen infection risk, influenced by resistance and its costs, can explain insect outbreaks.
- Heritable variation in infection risk suggests a significant role for natural selection in insect population dynamics.
- This model is broadly applicable, indicating natural selection for disease resistance may be a key factor in numerous insect outbreak phenomena.
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