INVESTIGADORES
MARONE Luis
artículos
Título:
Influence of temporal fluctuations in seed abundance on the diet of harvester ants (Pogonomyrmex spp.) in the central Monte desert, Argentina.
Autor/es:
PIRK, G.I., J. LOPEZ DE CASENAVE, R.G. POL & L. MARONE
Revista:
AUSTRAL ECOLOGY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Año: 2009 vol. 34 p. 908 - 919
ISSN:
1442-9985
Resumen:
Abstract Harvester ants usually go through temporal fluctuations in environmental seed abundance and composition
which could influence their behaviour and ecology. The aim of this study was to evaluate how these
fluctuations influence the diet of Pogonomyrmex rastratus, P. pronotalis and P. inermis (Hymenoptera, Formicidae) in
the central Monte desert during three consecutive growing seasons. Although seeds were the main item in the diet,
these ants turned more generalist when seed abundance of the most consumed species (grasses Aristida spp.,
Trichloris crinita, Pappophorum spp., Digitaria californica and Stipa ichu) was low. Accordingly, diversity of items in
the diet decreased with seed abundance in a logarithmical fashion, showing higher foraging efficiency for seeds at
higher seed abundance. Seed diversity, however, was not related to seed abundance as ants always included several
species in their diet, with alternating prevalence.The proportion of the most consumed species increased logarithmically
in the diet of P. rastratus and P. pronotalis along with their abundance in the environment probably as a
consequence of diet switching (from forb and shrub seeds to grass seeds) and by an increase in foraging efficiency
at higher seed densities. In contrast, foraging activity of P. inermis was very low at low seed abundance and its diet
included only the five grasses. Among the most consumed species, proportion in the diet was not associated with
relative abundance in the environment. Aristida spp., Pappophorum spp. and D. californica were overall highly
selected. However, the flexibility in the diet of P. pronotalis and P. rastratus and the low foraging activity of P. inermis
during periods of low resource abundance could attenuate potential top-down effects in the central Monte desert.
This study shows that bottom-up effects are important in ant-seed interactions and should be considered when
predicting and evaluating ants effects on seed resources.