Orthogonal fitness benefits of nitrogen and ants for nitrogen-limited plants in the presence of herbivores.
Ecology
; 98(12): 3003-3010, 2017 Dec.
Article
em En
| MEDLINE
| ID: mdl-28888051
ABSTRACT
Predictable effects of resource availability on plant growth-defense strategies provide a unifying theme in theories of direct anti-herbivore defense, but it is less clear how resource availability modulates plant indirect defense. Ant-plant-hemipteran interactions produce mutualistic trophic cascades when hemipteran-tending ants reduce total herbivory, and these interactions are a key component of plant indirect defense in most terrestrial ecosystems. Here we conducted an experiment to test how ant-plant-hemipteran interactions depend on nitrogen (N) availability by manipulating the presence of ants and aphids under different N fertilization treatments. Ants increased plant flowering success by decreasing the densities of herbivores, and the effects of ants on folivores were positively related to the density of aphids. Unexpectedly, N fertilization produced no changes in plant N concentrations. Plants grown in higher N grew and flowered more, but aphid honeydew chemistry stayed the same, and neither the density of aphids nor the rate of ant attraction per aphid changed with N addition. The positive effects of ants and N addition on plant fitness were thus independent of one another. We conclude that N was the plant's limiting nutrient and propose that addition of the limiting nutrient is unlikely to alter the strength of mutualistic trophic cascades.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Formigas
/
Herbivoria
/
Nitrogênio
Limite:
Animals
Idioma:
En
Revista:
Ecology
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Estados Unidos