1. PLANT RESPONSE TO INCREASED TEMPERATURE AND HERBIVORY Dejeanne Doublet // Terrestrial Ecology // John Parker Lab

2. WITH CLIMATE CHANGE, GLOBAL TEMPERATURES WILL CONTINUE TO RISE
Why temperature and herbivory? Climate change is a powerful driver of ecological, social, and economic change, and
Is expected to increase with ongoing globalization. Environmental temperature drives a number of important ecological interactions, including competition, predation, and herbivory, by determining the metabolic rates of ectothermic organisms
In summary, we show that herbivory, and therefore potential top-down control of plant biomass, is highly contingent upon environmental temperature.
Source: NASA

3. INSECT HERBIVORY DRIVES ECOLOGICAL AND EVOLUTION CHANGE IN PLANTS
The consumption of plants by insect herbivores represents one of the dominant species interactions on Earth and has been hypothesized to play a strong role in the diversification of plant species and their traits

4. But little is known about how TEMPERATURE AFFECTS HERBIVORY
The ecology and evolution of plant-herbivore relationships is, in part, governed by the reciprocal nature of their interaction and the complexity of communities. For example, plant traits and plant community structure are critical for determining insect occurrence and attack rates 

5. TEMPERATURE INCREASES CHANGE INSECT HERBIVORY PATTERNS
In 2014, Lemoine, Parker and Burkepile showed that increased temperature had variable effects on herbivory rates.
 Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 °C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. 

6. TEMPERATURE INCREASES CAN CAUSE CHANGES IN INSECT HERBIVORY PATTERNS
In 2014, Lemoine et al. showed that increased temperature had variable effects on herbivory rates.
But how does this relate to climate change?
Next step: Grow plants under different temperatures with and without herbivores
Not related to climate change because plants were not grown under different temps, next step grow plants under diff temps with and without herbivores

7. Our Question:
How do temperature and herbivory affect plant fitness?

8. THE SET-UP
Study site is right here on SERC property. Garden by the green house out back towards Education Center that Nate has spent the last couple of years putting together. Made up of 16 main plots where we can manipulate both temperature and herbivory.

9. THE SET-UP WARMED + HERBIVORY WARMED, NO HERBIVORY AMBIENT + HERBIVORY
AMBIENT, NO HERBIVORY
4 treatments

10. Bird’s Eye View of Plots
Warm
Ambient
Herbivory (Exposed to insects)
No Herbivory
(Netted)
No Herbivory (Netted)
Factorial, split-plot design
N= 32

11. Heated vs. Ambient Temperatures
Infrared heat, 3-4 degree increase, nighttime temp differences are greater, which actually portrays a climate change scenario more realistically than if temps were evenly increased all day.

12. A geneticist's dream plant
Oenothera biennis
aka
common evening primrose
A geneticist's dream plant
Planted at the end of last summer

13. Why Oeonothera biennis?
Native to eastern and central North American
Little genetic variability between plants
Host for various pollinators, seed predators and herbivores

14. The dominant herbivore: Japanese beetles (Popillia japinoca)

15. Introduced “Pest”
Source: National Agricultural Pest Information System

16. BEETLES ARRIVED IN EARLY JUNE AND STAYED THROUGH MID AUGUST
So the plants were allowed to grow under the different temperatures, then in June, the hungry Japanese beetles showed up and started doing their thing

17. Nearly all observed damage caused by
JAPANESE BEETLES

18. Estimated Leaf Damage Percent Leaf Damage No Herbivory Herbivory

19. 38%
more beetles were found in ambient plots

20. PLANTS WITH NO HERBIVORY BEGAN FLOWERING FIRST, AND DISPLAYED MORE FLOWERS
(AT FIRST)

21. AFFECT FLOWER PHENOLOGY?
HOW DOES HERBIVORY
AFFECT FLOWER PHENOLOGY?
And how will temperature play a role?

22. Weekly Flower Counts

23. Flower Phenology Timeline
Ambient
Herbivory Treatment
No herbivory
Herbivory
Flowers per Plant
Warm

24. Flower Phenology Timeline
Ambient
Herbivory Treatment
No herbivory
Herbivory
Peak # 1: Delayed by Herbivory
Flowers per Plant
Warm

25. Flower Phenology Timeline
Peak # 2: Delayed by Herbivory +
Expedited by Warming
Ambient
Herbivory Treatment
No herbivory
Herbivory
Flowers per Plant
Warm

26. Flower Phenology Timeline
Ambient
Herbivory Treatment
No herbivory
Herbivory
Flowers per Plant
Beginning of season: More flowers in NO Herbivory + Warmed treatments
Warm

27. Flower Phenology Timeline
Ambient
Herbivory Treatment
No herbivory
Herbivory
Flowers per Plant
End of season: More flowers in Herbivory + Ambient treatments
Warm

28. INSECT HERBIVORY DELAYS FLOWERING UNDER NORMAL AND WARM CONDITIONS BUT WHAT DOES THIS MEAN FOR OVERALL PLANT FITNESS?

29. What Defines Plant Fitness?
Fitness is defined by a plant’s ability to reproduce.
Fruit and seed production is a direct measurement of fitness.
Ability to reproduce  Drives evolutionary changes

30. To estimate fitness: 1. Count fruit 2. Estimate seed production 3
To estimate fitness: 1. Count fruit 2. Estimate seed production 3. Estimate seed mass

31. Fruit Count
No Herbivory
Herbivory
Average Fruit / Plant

32. Fruit Count
No Herbivory
Herbivory
Average Fruit / Plant

33. Seed Density within Fruit
Ambient
Warm
No Herbivory
Herbivory
Number of Seeds
per Gram Fruit

34. Seed Mass
Ambient
Warm
No Herbivory
Herbivory
Seed Mass (mg)

35. Seed Mass Ambient Warm Seed Mass (mg)
No Herbivory
Herbivory
Seed Mass (mg)
Lots of small, light-weight seeds

36. To Summarize…. AMBIENT, NO HERBIVORY WARMED, NO HERBIVORY
HIGH # of Fruit per Plant
LOW Density of Seeds
HIGH Seed Mass
WARMED, NO HERBIVORY
HIGH # of Fruit per Plant
HIGH Density of Seeds
LOW Seed Mass
AMBIENT + HERBIVORY
LOW # of Fruit per Plant
HIGH Density of Seeds
LOW Seed Mass
WARMED + HERBIVORY
HIGH # of Fruit per Plant
HIGH Density of Seeds
LOW Seed Mass
Under Ambient conditions, Herbivory caused plants to produce fewer fruit concentrated with more, light-weight seeds
When Warmed, Herbivory did not matter and plants produced a high amount of fruit that had lots of small, light-weight seeds

37. Conclusions 1 2 3 4
Both herbivory and temperature change the timing of flowering Herbivory decreased fruit production, only in ambient temperatures Warming deterred herbivory, contributing to an increase in the plant’s fruit production Temperature and herbivory have striking effects on plant phenology and fitness
In summary, we show that herbivory, and therefore potential top-down control of plant biomass, is highly contingent upon environmental temperature.

38. Current Literature Herbivory reduced seed predation by 77%
Plant benefits from leaf herbivory
Leaf herbivory has little impact on lifetime reproductive output
However, only 5 beetles were placed on each plant for 5 days

39. Furthering Current Research
Our methods provide a more realistic approach to understanding herbivory effects on plant fitness
Takes into account climate change, showing that temperature plays a major role in how herbivory affects plant fitness
Potential further studies: taking into account seed predators, pollinators

40. Acknowledgements Nate Lemoine Dr. John Parker Megan Palmer
Alison Cawood
Dozens of volunteers and citizen scientists
SERC Maintenance
Lauren, Dan and everybody else who work hard to make SERC a wonderful place to live and work