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

Tofolo, V.C. et al. — Spatial Pattern of Foraging in E. opaciventre
MATERIAL AND METHODS
Three nests of E. opaciventre were found in an urban area of 4,800 m 2 in
the city of Rio Claro, SP, Brazil (22º 22'42.31"S and 47º 33'38.67"W). This
grass-covered area was frequently used for garbage disposal and often set on
fire. The foraging pathways were determined based on the focal-animal sampling
method. Foragers were individually observed from the moment they left
the nest until they returned. As the ant moved, a numbered tag was placed
on the ground every 20 cm (Fig. 1). In cases where ants appeared disturbed
by the observer, the data were discarded. The duration of the foraging trip
and maximum foraging distance was recorded for 10 individuals per nest,
for a total of 30 observations. An analysis of variance with a 95%-confidence
interval was carried out in order to verify whether there were differences in
the foraging distance and time between the 3 nests studied. Then, BioEstat
software, version 3.0, was used to calculate the Spearman’s correlation coefficient
between the time and distance of foraging.
To evaluate the diet of the ants, we recorded the number of workers leaving
and entering the nest and we collected, with tweezers, the items that they
Fig. 1. Representation of the numbered tags placed every 20 cm to follow movement by the foragers
of Ectatomma opaciventre.
609