Diet and Spatial Pattern of Foraging in Ectatomma opaciventre ...
Diet and Spatial Pattern of Foraging in Ectatomma opaciventre ...
Diet and Spatial Pattern of Foraging in Ectatomma opaciventre ...
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616 Sociobiology Vol. 58, No. 3, 2011<br />
periods than closer areas. This would expla<strong>in</strong> the higher number <strong>of</strong> <strong>in</strong>dividual<br />
forag<strong>in</strong>g pathways <strong>of</strong> E. <strong>opaciventre</strong> closer to the nest.<br />
Therefore, forag<strong>in</strong>g strategies seem to depend upon several ecological<br />
variables, such as the distribution <strong>of</strong> food resources <strong>in</strong> time <strong>and</strong> space, food<br />
size <strong>and</strong> quality, competition, <strong>and</strong> predation. A colony must then have a spatial<br />
pattern <strong>of</strong> forag<strong>in</strong>g to collect food effectively <strong>and</strong> m<strong>in</strong>imize the chance<br />
<strong>of</strong> competition, <strong>in</strong> order to assure less energy waste <strong>and</strong> a greater <strong>in</strong>put <strong>of</strong><br />
resources <strong>in</strong> the shortest time.<br />
CONCLUSION<br />
The diversity <strong>of</strong> prey collected by E. <strong>opaciventre</strong> <strong>in</strong> the area studied was<br />
low, most probably because <strong>of</strong> the poor variety <strong>of</strong> species <strong>in</strong> the degraded<br />
environment <strong>and</strong> because the observations were carried out <strong>in</strong> the dry season.<br />
Collect<strong>in</strong>g other ant species as the major part <strong>of</strong> its diet was likely due to the<br />
abundance <strong>and</strong> high richness <strong>of</strong> <strong>in</strong>dividuals belong<strong>in</strong>g to several subfamilies <strong>of</strong><br />
Formicidae <strong>in</strong> the area studied. The forag<strong>in</strong>g trails <strong>of</strong> E. <strong>opaciventre</strong> presented<br />
a pattern similar to those observed <strong>in</strong> other Ectatomm<strong>in</strong>ae studied. With a<br />
s<strong>in</strong>uous pr<strong>of</strong>ile <strong>and</strong> directional fidelity, these trails avoid competition with<br />
other nests <strong>and</strong> lead to a better division <strong>of</strong> the resources explored. Although<br />
most trips were unsuccessful, the foragers did not stray too far from the nest,<br />
nor did they spend too much time forag<strong>in</strong>g. S<strong>in</strong>ce the area was dom<strong>in</strong>ated by<br />
grass, <strong>in</strong>tense sunlight <strong>and</strong> heat was present, which could have caused the ants<br />
physical exhaustion if they had extended the time spent outside the nest.<br />
ACKNOWLEDGMENTS<br />
We thank the National Council for Scientific <strong>and</strong> Technological Development<br />
(CNPq) for the f<strong>in</strong>ancial support.<br />
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