Hábitos de nidificação e resposta de Solenopsis saevissima (Smith) (Formicidae, Myrmicinae) à perturbação em ambiente urbano

Abstract

Ants of the genus Solenopsis are common in urban environments due to their capacity to explore resources and facility to establish nesting sites, which helps their proliferation and increases the occurrence of accidents with intruders. The aims of the present study were to characterize the nesting habits of Solenopsis saevissima (Smith), as well as to analyze behavioral responses to disturbances in colonies located in urban areas of Juiz de Fora, Minas Gerais. To study the nesting habits, observations were performed every two weeks from May 2011 to April de 2012, between 8:00 a.m. and 4:00 p.m. For each active colony the substrate and the dimensions of the nest were registered. To analyze the behavioral response, a shovel was used to disturb 30 colonies, and the displacement was verified with the aid of a wooden ruler (150cm long) positioned vertically over the disturbed colony and two (5m) measuring tapes perpendicular horizontally placed at the ground. Temperature and relative air humidity were registered during the observation period. The aggressive dispersion was observed in both directions, horizontal and vertical during three minutes, and the data were collected every 20 seconds. The results demonstrate that these ants are present throughout the year in this environment; that they remain active even in the coldest months and the substrate more utilized to build the nests was the undergrowth. The dry season (from April to August) can be considered more appropriate to controlling these insects due to the low number of active colonies. Regarding dislocation behavior, results show that the speed was significantly higher in the vertical than in the horizontal direction (p=0.0007), and it was not related to abiotic factors nor was dependent on the external size of the colony. These results add information on the biology and aggressive behavior of S. saevissima in urban environment.