INVESTIGADORES
FARJI-BRENER Alejandro Gustavo
artículos
Título:
Bottom-up effects may not reach the top: the influence of ant-aphid interactions on the spread of soil disturbances through trophic chains
Autor/es:
LESCANO, N.; FARJI-BRENER, AG; GIANOLI, ERNESTO; TOMAS. CARLO
Revista:
PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B: BIOLOGICAL SCIENCES.
Editorial:
ROYAL SOC
Referencias:
Lugar: Londres; Año: 2012 vol. 279 p. 3779 - 3787
ISSN:
0962-8452
Resumen:
Soil disturbances that increase nutrient availability may trigger bottom-up cascading effects along trophic
chains. However, the strength and sign of these effects may depend on attributes of the interacting
species. Here, we studied the effects of nutrient-rich refuse dumps of the leaf-cutting ant, Acromyrmex
lobicornis, on the food chain composed of thistles, aphids, tending ants and aphid natural enemies.
Using stable isotopes tracers, we show that the nitrogen accumulated in refuse dumps propagates
upward through the studied food chain. Thistles growing on refuse dumps had greater biomass and
higher aphid density than those growing in adjacent soil. These modifications did not affect the structure
of the tending ant assemblage, but were associated with increased ant activity. In contrast to the expec-
tations under the typical bottom-up cascade effect, the increase in aphid abundance did not positively
impact on aphid natural enemies. This pattern may be explained by both an increased activity of tending
ants, which defend aphids against their natural enemies, and the low capacity of aphid natural enemies to
show numerical or functional responses to increased aphid density. Our results illustrate how biotic inter-
actions and the response capacity of top predators could disrupt bottom-up cascades triggered by
disturbances that increase resource availability.