Série temporal discreta do comportamento outonal da saúva do nordeste

Abstract

A scientific investigation was developed at the Campus of the Federal University of Ceará, in Fortaleza County, State of Ceará, Brazil, during the autumn of 1992. The field assays were carried out in an infested area with six nests of the northeast leaf-cutting ant, Atta opaciceps Borgmeier, 1939 (Hymenoptera:Formicidae) per hectare to determine the periodogram and the behaviour patterns of the species through the autumn. Foraging activity was stimulated by offering oat flakes on the ants' trail which started at an exit feeding hole. The stimulus source was placed c.a., 2,0m from the referred hole and the worker's activity tracked through a 24-hour cycle. The time-series analysis disclosed that the northeast leaf-cutting ant is an active insect during the photophase and the scotophase of the autumn. However, the scotophase activity was 2,43 times higher than that observed for the photophase. The insect activity is affected by the air temperature, solar radiation and relative humidity. The peak Of activity is inversely correlated to the peak of solar radiation. The insect's autumnal activity is higher in may and lower in april. The northeast leaf-cutting ant photophase and scotophase foraging autumnal activities were 5,39 and 1,74 times higher than those observed during the summer, respectively. Workers of A. opaciceps were 2,41 times more active in the autumn when compared to the summer.