Climate-Change
Insects are ectotherms
- All aspects of life histories determined by temperature
- Rapid responses to changing climate
- Evidence to date:
- Behavioral changes
- Voltinism shifts
- Range expansion/contraction
Climate and biotic disturbance: it's complicated
Climate
- Insect/pathogens (direct effect)
- Survival
- Reproduction
- Disoersak
- Geographic distribution
- Tree physiology/resistance (indirect effects)
- Competitors, natural enemies (indirect effects)
All additionally impacted by anthropogenic impacts (fragmentation, pollution, fire, alien ivnasives, etc.)
Potential effects of global warming on individual forest insects
| Positives | Negatives |
|---|---|
| Reduced winter mortality | Phenological asynchrony |
| Increased thermally benign habitat | Reduced thermally benign habitat |
| Reduced host resistance | Shift / depletion of hosts |
| Escape from competitors / predators | Competition/predation from invasive species |
| Increased host range (more host species) | Dispersal costs to new habitats |
Potential effects of global warming on eruptive insect populations
- Altered outbreak frequency/duration
- Modified herbivory/damage rates
- Range expansion/contraction
- Novel host species associations
Prehistoric responses by forest insects to climate change
- Warming does not equal fitness benefit to all insects; however...
- Significant increase in herbivory during PETM
- Decline in herbivory with subsequent cooling
- Assumption is that trends will follow suit
Recent climate trends in western Canada
- Significant warming throughout Western North America to Date
- Considerably more warming predicted in the future
- Growing evidence for increased insect disturbances