In South America, Solenopsis saevissima and S. invicta are the most common fire ants. Nests are founded in areas under anthropic interference like urban or rural areas, but S. invicta is found preferentially in those with the greatest anthropic interference. However, we do not know the rates at which they exist in anthropized areas next to high density of native vegetation. Areas with 60 to 90% of native Atlantic Forest were selected to verify the occurrence of both species in rural and urban areas. We investigated the molecular diversity and applied the reconstruction of the ancestral state analysis for each species. A total of 186 nests were analyzed and we found that the two species had the same proportion in the urban area. However, S. saevissima had a higher rate of prevalence in the rural area, in addition to having a greater number of haplotypes and ancestry associated with this type of habitat for the region. S. invicta had the same number of haplotypes in both rural and urban regions, and less haplotypic diversity. We conclude that S. saevissima is a species typically associated with rural areas and S. invicta, although present, is not dominant in urban areas.

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In the leaf litter, ants have various nesting resources available, such as live or dead trunks, twigs, leaves, fruits and seeds. On the twigs, there are adults and immature individuals, but also the queen and winged. The production of wings requires time and energy from the colony. The objective of this study was to investigate the presence of winged in ant colonies in twigs on the leaf litter. Our prediction is that the richness and abundance of winged in twigs are the greatest in rainy months. We collected all twigs with ants in 552 plots with 16 m2, totaling 8,832 m2 of leaf litter, in areas located in the Brazilian Atlantic Domain. We compared the species richness and the number of colonies with and without winged, as well as the number of winged over a year. In total, we collected 1,521 twigs with colonies belonging to 92 species of ants. The rate of twigs with winged was low, about 12%. In colonies with winged, the total number of twigs, species and amount of winged does not differ between the months considered dry and rainy. The majority of winged species are leaf litter dwellers, such as Linepithema neotropicum, recorded with the highest amount of winged irrespective of the period. Arboreal species colonized 15% of the twigs and, in 1/3 of these species, winged were recorded as part of the composition of the colony. Although winged represent a small percentage of the colony in twigs, our results indicate that this feature is important for the life cycle of 44% of the species that occupy twigs, considering that winged are fundamental for the dispersion of the colony.

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