Formigas lava-pés solenopsis saevissima (smith, 1855): do voo nupcial ao controle populacional

Abstract

The fire ant Solenopsis saevissima is native to Brazil, and has a common distribution in the southeastern region of the country, but despite this, there are few studies that focus on natural history, behavior and natural means of control. Thus, the present work aimed to understand the reproductive nuptial flight, to verify the occurrence of reproductive strategies in relation to the type of foundation, to describe the behavior of queens and workers in the initial phase of the colonies and to verify the effectiveness of control methods with bioactive compounds of plants. Nuptial flights were most abundant in the rainy and hot season. The flight is related to climatic factors, with a drought period followed by precipitation. Favorable temperature and air humidity encourage winged departures in the morning. The workers participate in this process, protecting the reproductive’s and opening the holes for their exit. The flights are monosexual, with males leaving first and winged climb high points for takeoff. At the end of the event the fertilized queens fall to the ground and look for suitable nesting sites. To evaluate the diversity in the foundation strategy, freshly fertilized queens were collected and maintained in haplometrose and pleometrose groups under laboratory conditions. The associations had reproductive success, and the highest percentage of success was recorded for groups of five queens. In addition, this group reached first post-emergence, generated more workers and their queens had longer survival. During the development of the biological cycle, queen mortality was higher at the beginning of the foundation, before and during oviposition and postemergence. The etogram showed that the behavior of queens changes according to the different periods of the colony cycle, and that at first they are linked to exploration and interaction with the environment, and with the emergence of the first eggs the interaction with the offspring becomes more intense. In the post-emergence, the workers actively act to protect the immature. For control four biocidal substances were tested at different concentrations. After 24 hours of exposure of workers to the compounds, there was 100% mortality at concentrations of 0.5 and 0.75 mg / ml for thymol and carvacrol, respectively, and 2.5 and 10 mg / ml for eugenol and (E). cinnamaldehyde, which shows their efficacy as a formicidal agent, highlighting thymol and carvacrol.