Plant genotype, water stress and their interaction are among the factors contributing to the susceptibility of plants to herbivory. The plant's nitrogen concentration, a critical and often limiting nutrient, differs with plant genotype and water stress. Still, few studies have investigated the impact of the interaction between genotype and water stress on herbivory and plant nitrogen. We established a common garden in Duluth, MN, of tall goldenrod, Lace bugs had oviposition, nymph and adult preferences among host plant genotypes, water treatments and among genotype and water treatment combinations. Nymph and adult survival and adult mass varied significantly due to plant genotype, water treatment, the interaction between plant and water treatment and the interaction of treatment with lace bug density. Oviposition preference and offspring performance were significantly positively related. Leaf nitrogen increased with the increasing severity of the water limitation in the absence of lace bugs. However, in the presence of lace bugs, there was no difference in nitrogen among water treatments. We hypothesize that lace bugs reduce leaf nitrogen concentration to a lower threshold and then move between plants until nitrogen concentration equalises among all plants.
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Plasticity in plant traits, including secondary metabolites, is critical to plant survival and competitiveness under stressful conditions. The ability of a plant to respond effectively to combined stressors can be impacted by crosstalk in biochemical pathways, resource availability and evolutionary history, but such responses remain underexplored. In particular, we know little about intraspecific variation in response to combined stressors or whether such variation is associated with the stress history of a given population. Here, we investigated the consequences of combined water and herbivory stress for plant traits, including relative growth rate, leaf morphology and various measures of phytochemistry, using a common garden of Plants responded to water limitation alone by increasing the evenness of UV‐absorbent secondary metabolites and to herbivory alone by increasing the richness of metabolites. However, plants that experienced combined water and herbivory stress exhibited similar phytochemical diversity to well‐watered control plants. This lack of plasticity in phytochemical diversity in plants experiencing combined stressors was associated with a reduction in relative growth rates. Leaf chemistry means and plasticities exhibited clinal variation corresponding to seed source water deficits. The total concentration of UV‐absorbent metabolites decreased with increasing water availability among seed sources, driven by higher concentrations of flavonol glycosides, which are hypothesized to act as antioxidants, among plants from drier sites. Plants sourced from drier sites exhibited higher plasticity in flavonol glycoside concentrations in response to water limitation, which increased phytochemical evenness, but simultaneous herbivory dampened plant responses to water limitation irrespective of seed source.
- Award ID(s):
- 2145757
- NSF-PAR ID:
- 10479723
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Ecology
- Volume:
- 112
- Issue:
- 2
- ISSN:
- 0022-0477
- Format(s):
- Medium: X Size: p. 338-347
- Size(s):
- p. 338-347
- Sponsoring Org:
- National Science Foundation
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