Acorn defenses to herbivory from insects: Implications for the joint evolution of resistance, tolerance and escape

Xiao, Zhishu; Harris, Marvin K.; Zhang, Zhibin

doi:10.1016/j.foreco.2006.10.024

Cited by 59 publications

(73 citation statements)

References 32 publications

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“…Thus, larger seeds also satiated the weevil larvae, and so a larger acorn size increased the likelihood of embryo survival because it has more mass to be consumed [12,14,23,24]. These experiments reinforce the results obtained by others [12,14,24] about the importance of the satiation mechanism by means of larger seeds.…”

Section: Effect Of Sizesupporting

confidence: 82%

“…However, infested larger seeds have shown a better germination ratio than infested smaller acorns according to the results found in other experiments [14,22,24]. To understand this result we should be aware of two facts: first, that a larger acorn size means it has larger cotyledons and second that insects oviposit on the basis of acorn, near the cupule [26].…”

Section: Effect Of Sizementioning

confidence: 78%

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Ecological Implications of Acorn Size at the Individual Tree Level in Quercus suber L.

2013

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Few studies have determined the influence of acorn size on germination and predation percentage at tree level. To evaluate the seed size influence at individual tree level, trees producing two different sizes of acorn were chosen. Our results show that smaller acorns were significantly more infested (49.6-75.3%) than larger ones (11.0-27.33%). About germination, big acorns achieved the best germination percentage compared to the smaller ones (18% in infested and 76% in sound acorns for the small acorn group versus 69.3% in infested and 93.3% in sound acorns belonging to the big acorn group). We also found that there was a difference in behaviour between big and small seeds at tree level. The same size belonging to different functional groups presented a difference at the behavioural level per tree. Infested small acorns from trees 8 and 10 had only 33 and 13% germination, while big acorns from trees 2, 3, and 6 (there was no difference between both sizes) presented 67, 97, and 83%, respectively. These results indicate that the production of acorns with two different sizes could be a strategy for species regeneration, producing each size for a different purpose.

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Section: Effect Of Sizesupporting

confidence: 82%

Section: Effect Of Sizementioning

confidence: 78%

Ecological Implications of Acorn Size at the Individual Tree Level in Quercus suber L.

2013

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“…Higher cotyledon damage might have occurred during the course of the study but, due to the large seed reserves of Q. germana, its germination rate was unaffected. This pattern has been documented for other species with large acorn reserves (Xiao, Harris, & Zhang, 2007;Yi & Yang 2010).…”

Section: Light Environmentssupporting

confidence: 71%

Germinación y emergencia de plántulas de cuatro especies de encino amenazadas

Cruz

López‐Barrera

Ramos-Prado

2016

MYB

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Germination and emergence of the endangered cloud forest oak species Quercus germana, Q. insignis, Q. sartorii and Q. xalapensis were observed under different light conditions (sun vs. shade) in a secondary forest fragment (SFF) and in a greenhouse (GRE). Seed weight variability was evaluated for each species and its relationship to germination and emergence determined. After 60 days, a total of 62.17% of the acorns had germinated and 37.79% had emerged in both experiments. Germination was highest in Q. sartorii (71.83% ± 2.09%), followed by Q. germana (66.33% ± 2.06%), Q. insignis (60.83% ± 2.34%) and Q. xalapensis (53.50% ± 2.32%). In the GRE, Q. insignis germination was higher under sun (62.00% ± 4.73%) than shade (48.00% ± 5.12%), whereas its emergence was the lowest (37.66% ± 3.46%) compared to other species in both light environments. In the SFF, germination and emergence only differed among species; Q. xalapensis germination was lowest (47.00% ± 3.11%) and Q. sartorii emergence was highest (58.66% ± 3.35%), compared to the other species. Acorn weight did not influence germination or emergence in any species. The implications of this study are discussed, along with recommended propagation techniques for growing oaks for forest restoration in disturbed areas.Keywords: early seedling establishment, light environment, Quercus, seed mass, tropical montane cloud forest.resumen La germinación y emergencia de encinos amenazados del bosque de niebla, Quercus germana, Q. insignis, Q. sartorii y Q. xalapensis fue evaluada bajo diferentes condiciones lumínicas (sol vs. sombra) en un fragmento de bosque secundario (SFF) y un invernadero (GRE). Para cada una de las especies, la variabilidad del peso de la semilla fue relacionada con la germinación y emergencia. Después de 60 días, en ambos experimentos, un total de 62.17% de las bellotas germinaron y 37.79% emergieron. La germinación fue mayor en Q. sartorii (71.83% ± 2.09%), seguido de Q. germana (66.33% ± 2.06%), Q. insignis (60.83% ± 2.34%) y Q. xalapensis (53.50% ± 2.32%). En el GRE, la germinación de Q. insignis fue mayor bajo el sol (62.00% ± 4.73%) que bajo la sombra (48.00% ± 5.12%), mientras que su emergencia fue la más baja (37.66% ± 3.46%) comparada con otras especies en ambos ambientes lumínicos. En el SFF, la germinación y emergencia solo fueron diferentes entre especies; Q. xalapensis registró la germinación más baja (47.00% ± 3.11%) y Q. sartorii la emergencia más alta (58.66% ± 3.35%) comparada con el resto de las especies. El peso de la bellota no influyó en la germinación y emergencia de las especies. Se discuten las implicaciones de este estudio, así como recomendaciones sobre técnicas de propagación para la producción de encinos para restaurar bosques en áreas perturbadas.Palabras clave: establecimiento temprano de plántulas, ambiente lumínico, Quercus, peso de semilla, bosque de niebla.

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“…Curculio haroldi and several other unidentified species) and moths (e.g., Cydia sp., Archips sp. and one unidentified gelechiid moth) (Xiao et al, 2004b(Xiao et al, , 2007; Z. Xiao, unpubl.…”

Section: Methodsmentioning

confidence: 99%

Seed–predator satiation and Janzen–Connell effects vary with spatial scales for seed-feeding insects

Xiao

Holyoak³

et al. 2016

Ann Bot

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Background and AimsThe Janzen-Connell model predicts that common species suffer high seed predation from specialized natural enemies as a function of distance from parent trees, and consequently as a function of conspecific density, whereas the predator satiation hypothesis predicts that seed attack is reduced due to predator satiation at high seed densities. Pre-dispersal predation by insects was studied while seeds are still on parent trees, which represents a frequently overlooked stage in which seed predation occurs.Methods Reproductive tree density and seed production were investigated from ten Quercus serrata populations located in south-west China, quantifying density-dependent pre-dispersal seed predation over two years by three insect groups.Key Results Acorn infestation was nearly twice as high in the low-seed year as that in the high-seed year, with considerable spatio-temporal variation in the direction and magnitude of density-dependent pre-dispersal seed predation evident. Across whole populations of trees, a high density of reproductive trees caused predator satiation and reduced insect attack in the high-seed year. Within individual trees, and consistent with the Janzen-Connell model, overall insect seed predation was positively correlated with seed production in the low-seed year. In addition, there was variation among insect taxa, with positive density-dependent seed predation by Curculio weevils in the high-seed year and moths in the low-seed year, but apparent density independence by Cyllorhynchites weevils in both years.Conclusions The overall trend of negative density-dependent, pre-dispersal seed predation suggests that predator satiation limited the occurrence of Janzen-Connell effects across Q. serrata populations. Such effects may have large impacts on plant population dynamics and tree diversity, depending on the extent to which they are reduced by counteracting positive density-dependent predation for seeds on individual trees and other factors affecting successful recruitment.

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Acorn defenses to herbivory from insects: Implications for the joint evolution of resistance, tolerance and escape

Cited by 59 publications

References 32 publications

Ecological Implications of Acorn Size at the Individual Tree Level in Quercus suber L.

Ecological Implications of Acorn Size at the Individual Tree Level in Quercus suber L.

Germinación y emergencia de plántulas de cuatro especies de encino amenazadas

Seed–predator satiation and Janzen–Connell effects vary with spatial scales for seed-feeding insects

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