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Common buckwheat

Eriogonum fasciculatum

Preliminary results - MJ Induction

Total emission increases with Methyl Jasmonate induction at varying concentrations across species.

5mM sufficiently induces across species.

Do birds increase predation on Methyl Jasmonate induced plants?

No significant effect of Methyl Jasmonate middle (5mM) concentration optimal.

Fig. 1. May 2023 - Control: n=3, 1mM: n=5, 5mM: n=5, 15mM: n=5 (F₍₃₎ = 2.14, P = 0.09).

Fig. 2. March 2024 - Control: n=6, 5mM: n=6, 10mM: n=6 (F₍₂₎ = 0.56, P = 0.57).

VOCs collected by bags adapted with a charcoal trap over non-flowering sections.

VOCs are pulled through the trap for two hours at a flow rate of 250mL/min, 30min to equilibrate.

Traps eluted with a solution of dichloromethane and an internal standard (naphthalene) and analyzed by Gas Chromatography – Mass Spectrometry.

Compounds will be identified using the NIST library, and concentrations will be assessed by comparing to the internal standard.

The application of MeJa can effectively inducing the emission of VOCs, but responses are often species-specific

Commonly upregulated VOCs include terpenes and green leaf volatiles (GLVs)

To assess these species responses, plants sprayed every two days for two weeks (4 sprays), VOCs collected the day after final spray.

Part 1

Plants sprayed every two days across a four-week period (7 total)
90ml across three branches (same per leaf induction as prior tests), 5mM MJ solution

Allows VOC to be sampled on non-prey branch
Increased total VOC emission

VOCs resampled on the same individuals

UCI San Joaquin Marsh

Wetlands & Sage Scrub

Irvine, CA

UCI Ecological Preserve

Coastal Sage Scrub

Irvine, CA

30mL per plant

Induction Solution:

94.55% Distilled water

5% Ethanol (70%)

0.35% 1M MeJa

0.1% Tween20

Only Methyl Jasmonate induction at 15mM had a significant effect.

Fig. 3. May 2023 - Control: n=3, 1mM: n=3, 15mM: n=3 (F₍₂₎ = 6.45, P = 0.002).

Fig. 4. March 2024 - Control: n=6, 5mM: n=6, 10mM: n=6 (F₍₂₎ = 1.89, P = 0.15).

Methyl Jasmonate concentrations 1mM and 5mM had a significant induction effect.

Fig. 5. May 2023 - Control: n=3, 1mM: n=3, 15mM: n=3 (F₍₂₎ = 7.97, P < 0.001).

Fig. 6. March 2024 - Control: n=6, 5mM: n=6, 10mM: n=6 (F₍₂₎ = 3.29, P =0.04).

1 clay caterpillar & 1 mealworm (Tenebrionid larvae) with tanglefoot deployed on the distal end of each sprayed branch, ~ < 1ft apart
Checked 7 times on the day of spraying & mealworm replaced - clay caterpillars smoothed upon placement and reset upon attack, replaced if missing; checked and reset each spray.
Live prey typically receive higher predation rates due to being more realistic - clay was placed beneath in order to determine predator identity

Artemisia californica

Baccharis salicifolia

Eriogonum fasciculatum

Mule fat

Baccharis salicifolia

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California sagebrush

Artemisia californica

Mule fat

Baccharis salicifolia

1 Turlings, T. C. et al. Science 250, 1251–1253 (1990) 2 Gagliardo, A. J. Exp. Biol. 216, 2165–2171 (2013) 3 Fracasso, G. et al. Curr. Zool. 65, 53–59 (2019) 4 Yang, S.-Y. et al. PLOS ONE 10, e0130191 (2015) 5 Turlings, T. C. J. et al. Annu. Rev. Entomol. 63, 433–452 (2018) 6 Amo, L. et al. Ecol. Lett. 16, 1348–1355 (2013) 7 Mäntylä, E. et al. Ecol. Lett. 7, 915–918 (2004) (Van Bael et al. 2003, Mooney et al. 2010a, Mäntylä et al. 2011).

The role of plant volatiles in mediating indirect defense by insectivorous birds

Predation Assay sample size
MJ treatment	ERFA	ARCA
Control	54	54
5mM	54	54

Next Steps & Implications

Further analyze VOC samples, quantify and quality. Run the remaining samples (6 per treatment per species from March, 12 per from May). Include external standards or KOVATS to ID
Rerun predation assay again spring 2025. Determine whether bird behavior or populations affected results this year. Potentially use a different metric to assess – observational?
As plant defensive traits are predicted to trade off due to redundancies, bird may have a role in selecting for indirect defense traits and ultimately plant evolution in response to the third trophic level

>1 m apart

	MJ Treatment	Flying predator attacked mealworm	Bird attacked mealworm	Bird attacked clay caterpillar
Artemisia californica	5mM	4	0	2
Artemisia californica	Control	2	2	2
Eriogonum fasciculatum	5mM	51	6	4
Eriogonum fasciculatum	Control	73	2	6

Bird attacked clay caterpillar

Deployed mealworm

Ant attacked mealworm

Flying predator attacked mealworm

Bird attacked mealworm

Part 2

Lydia S. Dean¹, John Powers¹, Andrea Galmán², Carla Vázquez-González², Christian Gutierrez¹, Jaycee Fahrner¹, & Kailen A. Mooney¹

¹Dept of Ecology and Evolutionary Biology, Univ. of California, Irvine, CA, USA. ²Misión Biológica de Galicia, National Spanish Research Council (CSIC), Pontevedra, Spain.

Birds exert strong top-down control of insect herbivore populations, and provide indirect resistance to plants - mechanisms that mediate this have been less studied
“Cry for help” hypothesis¹: recruitment of herbivore natural enemies via herbivore-induced volatile organic compounds (VOCs)
Birds have been found to use olfaction in navigation, kin selection, and foraging^2-4
Chewing herbivores (e.g., caterpillars) trigger the synthesis of methyl jasmonate (MeJa)⁵
Past work has explored this in situ and in aviaries, finding mixed responses of bird attraction to VOCs^6,7
Studies vary in location, herbivory simulation method, as well as bird and plant species, preventing any potential generalization and warranting further research to assess underlying mechanisms

Trends in attack - Total attacks across treatments over

4-week period (1,512 checks)

2024

Are plant volatiles induced with Methyl Jasmonate in these species?

Total VOC Emission (Ions)