Species Composition of Root-Feeding Macroarthropods in a Subalpine Grassland Associated With Pine Forest in Mexico

Morón‐Ríos, Alejandro; Jaramillo, Vı́ctor J.; Dirzo, Rodolfo

doi:10.4039/ent12971-1

Cited by 11 publications

(3 citation statements)

References 27 publications

(33 reference statements)

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“…Within roots, TRs were the most defended organ, except in the wetland species N. officinale , which lacked a TR. Most insect herbivores in soils are found in the upper layer where the TR is located, making TRs more vulnerable to herbivory than LRs or FRs (Morón‐Ríos, Jaramilli & Dirzo ; Pinski, Mattson & Raffa ). When root herbivores are confined to this layer, their damage often increases plant mortality (Davidson & Roberts ; Tsunoda, Kachi & Suzuki , b).…”

Section: Discussionmentioning

confidence: 99%

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Root and shoot glucosinolate allocation patterns follow optimal defence allocation theory

2017

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Summary Optimal defence allocation theory (ODT) is one of the most prominent theoretical frameworks to explain the allocation of defence compounds within plants. It predicts that the most valuable and vulnerable plant organs have the highest levels of chemical defence. The ODT has been well worked out and experimentally tested for shoot defences, but not for root defences. To assess if ODT principles apply similarly to roots and shoots, we examined glucosinolates in above‐ground and below‐ground organs of nine plant species belonging to two families. In order to evaluate whether ODT equally applies to shoot and root organs, we designed a conceptual model in which above‐ground and below‐ground organs were assigned to orders of importance to plant performance. We hypothesized that organs constituting the plant's core structure are better protected than more distal organs. The nine plant species were cultivated, and their roots and shoots were harvested and divided into three orders for glucosinolate analysis. Using a specialist (Delia radicum) and a generalist (Amphimallon solstitiale) root herbivore, we also experimentally tested the hypothesis that the generalist herbivore prefers to feed on fine roots (FRs) with a low glucosinolate concentration, while the specialist prefers taproots (TRs) with a high glucosinolate concentration. We found that both in roots and shoots, the higher ordered core structural organs (TRs and stems) had the highest levels of glucosinolates. Below‐ground, TRs and lateral roots were better protected than the more distal, and less costly, FRs in seven out of nine species tested. The specialist root herbivore preferred feeding on the highly defended TRs, which is in line with what has been found for above‐ground specialist herbivores. Moreover, the glucosinolate concentration in roots overall was significantly higher than that in shoots. Synthesis. These results support the hypothesis that Optimal defence allocation theory (ODT) generally applies to glucosinolate allocation in above‐ground and below‐ground organs and may mainly serve to maintain the integrity of the main plant structure. Moreover, it suggests that above‐ground and below‐ground insect herbivores independently exert similar selection pressures on defence allocation patterns in roots and shoots.

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Section: Discussionmentioning

confidence: 99%

“…Moreover, in the soil, there is a spatial stratification of the risk of herbivory. Most arthropod root herbivores occur in the top horizon of the soil (Morón‐Ríos, Jaramilli & Dirzo ; Pinski, Mattson & Raffa ). Therefore, they are more likely to attack the root base (i.e.…”

Section: Introductionmentioning

confidence: 99%

Root and shoot glucosinolate allocation patterns follow optimal defence allocation theory

2017

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“…Within root systems, glucosinolate concentrations are generally higher in tap and lateral roots than in fine roots (Tsunoda, Krosse, & van Dam, ). This may reflect optimal defence allocation patterns, because most root herbivores occur at the main root just under the soil surface (Morón‐Ríos, Jaramilli, & Dirzo, ; Pinski, Mattson, & Raffa, ). Herbivory on the main root also causes the most profound damage in terms of fitness loss (Davidson & Roberts, ; Erwin, Geber, & Agrawal, ; Tsunoda, Kachi, & Suzuki, ,b).…”

Section: Introductionmentioning

confidence: 99%

Locally and systemically induced glucosinolates follow optimal defence allocation theory upon root herbivory

2018

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Herbivore‐induced defences in plants are considered a strategy to manage multiple interactions while saving resources. The optimal defence theory (ODT) is one of the most prominent theoretical frameworks to explain the defence allocation patterns within plants. It was recently shown that the ODT generally applies to constitutive glucosinolate (GSL) allocation in shoot and root organs. Previous studies showed that both root and shoot herbivore feeding may alter defence allocation over plant organs. For shoots, the effect depends on where the herbivores feed. It is as yet unknown whether similar principles apply to root‐herbivore‐induced GSLs. To analyse the effects of root localized herbivore feeding on GSL allocation, we conducted a pot experiment using Anomala cuprea grubs and four Brassicaceae; Brassica rapa, B. nigra, B. oleracea and Sinapis alba. Individuals of these four plant species were grown in dedicated mesocosms. The grubs were confined either to the bottom soil, the middle section or the topsoil. Plants grown in the same set‐ups but without root herbivores served as controls. Glucosinolate levels of the leaf lamina, petiole and stem as well as of the taproot, lateral roots and fine roots were measured after 8 days of herbivory. Plant biomass reduction due to herbivory was the largest when herbivores were confined to the topsoil. In the three Brassica species, taproot GSL levels increased upon herbivory independent of where the root herbivores were feeding. Glucosinolate levels in fine roots and shoots, on the other hand, hardly responded to root herbivory. Indole GSLs, which are more effective to pathogens than to herbivores, were more strongly induced than aliphatic and aromatic GSLs, especially in the taproots. Sinapis alba did not show remarkable increments in any GSL level upon herbivory. These results show that locally and systemically induced defences in roots are consistent with the ODT: The taproot which is the most vulnerable and valuable to plant performance shows the highest increase in defence induction. The induced GSL profiles suggest that the response may not only target herbivores, but may also help to prevent secondary infection by microbial pathogens. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13147/suppinfo is available for this article.

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Belowground Herbivores and Ecosystem Processes

Masters¹

2008

Ecological Studies

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Species Composition of Root-Feeding Macroarthropods in a Subalpine Grassland Associated With Pine Forest in Mexico

Cited by 11 publications

References 27 publications

Root and shoot glucosinolate allocation patterns follow optimal defence allocation theory

Root and shoot glucosinolate allocation patterns follow optimal defence allocation theory

Locally and systemically induced glucosinolates follow optimal defence allocation theory upon root herbivory

Belowground Herbivores and Ecosystem Processes

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