Diet and Spatial Pattern of Foraging in Ectatomma opaciventre ...

608 Sociobiology Vol. 58, No. 3, 2011
influenced. There is also a relation between individual and collective search
patterns, since the forager may influence the search patterns of a nestmate
through communication. Therefore, the distribution of resources in space
and time should be the main influences upon the organization of search
(Traniello 1989).
There is a tendency for ant species with small colonies to forage individually
and not to present complex recruitment systems, because individuals interact
directly with few foragers. On the other hand, colonies with a lot of individuals
rely on long-term chemical communication between the individuals, allowing
for rapid recruitment of numerous foragers. Between these extremes, there
are intermediate behaviors such as tandem running, group recruitment, and
mass recruitment (Beckers et al. 1989). In Ectatomminae, foragers may use
a wide variety of strategies to obtain food. The foraging methods may vary
from hunting independently, with no cooperation during food search and
collection, to various degrees of cooperation, with different levels of communication
and recruitment between nestmates. However, a wide range of
feeding habits can be observed from species to species, including the collection
of seeds, fruits, living prey, and insect secretions (Hölldobler & Wilson
1990; Medeiros & Oliveira 2009).
Among the ants of the genus Ectatomma, endemic to South and Central
America (Brown-Jr 1958; Bolton 1995), several foraging strategies may occur,
such as ambush predation, solitary hunting, cooperative and group hunting,
and even cleptobiosis (Perfecto & Vander Meer 1993; Schatz & Wcislo 1999).
As their colonies are small, foraging is more often solitary (Hölldobler &
Wilson 1990). With a large, functional sting and well-developed mandibles,
they are capable of subjugating large, aggressive prey, a characteristic typical
of essentially predator species (Hölldobler & Wilson 1990; Wheeler 1986;
Giannotti & Machado 1992; Fernández 1991; Oliveira & Brandão 1991;
Del-Claro & Oliveira 1999; Pie 2004). Regarded as a generalist predator,
Ectatomma opaciventre uses the hypogeal stratum for nesting and the epigeal
for foraging a wide variety of arthropods and annelids, living or recently dead
(Fernández 1991; Pie 2004).
The objective of this research was to determine individual foraging pathways
of workers of E. opaciventre and identify prey types in the diet of this
species in an anthropic area.