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Population studies of tropical butterflies are still scarce considering the huge diversity of species worldwide, and historical data are even more limited.The present paper describes in detail the population parameters of M. cymo salonina from a semideciduous forest in the interior of São Paulo state, Brazil. A mark-release-recapture (MRR) program was carried out in a forest fragment in Sumaré municipality, from August 17, 1974 to October 26, 1977. In total, 2892 individuals were captured and marked (1620 males and 1272 females). The estimated population size varied from two to 1349 individuals per day for males and from one to 908 for females. For both sexes, the population showed a markedly seasonal pattern in the three studied years, with a distinct peak at the end of the wet season, followed by a decrease in numbers at the beginning of the dry season, maintaining low numbers until the mid-wet season. The overall sex ratio (56% male) was male-biased, but considering the months separately, this bias was reported in only nine out of the 25 tested months. The residence time (based on recaptured individuals) varied from one to 91 days for males and from one to 112 for females; the average residence time of males and females was not significantly different. The age structure was unstable and showed a clear predominance of new individuals at the onset of the population peaks, followed by an increase in the proportion of intermediate and old individuals in the ensuing months. Survival curves were similar for both sexes, approaching a type II survival curve. The present study provides novel information regarding this group, indicating that general patterns are still not well explored. Therefore, any further studies on ithomiines, including different species and populations of already studied species, are highly encouraged. [ABSTRACT FROM AUTHOR]

Species that differ in their social system, and thus in traits such as group size and dispersal timing, may differ in their use of resources along spatial, temporal, or dietary dimensions. The role of sociality in creating differences in habitat use is best explored by studying closely related species or socially polymorphic species that differ in their social system, but share a common environment. Here we investigate whether five sympatric Anelosimus spider species that range from nearly solitary to highly social differ in their use of space and in their phenology as a function of their social system. By studying these species in Serra do Japi, Brazil, we find that the more social species, which form larger, longer-lived colonies, tend to live inside the forest, where sturdier, longer lasting vegetation is likely to offer better support for their nests. The less social species, which form single-family groups, in contrast, tend to occur on the forest edge where the vegetation is less robust. Within these two microhabitats, species with longer-lived colonies tend to occupy the potentially more stable positions closer to the core of the plants, while those with smaller and shorter-lived colonies build their nests towards the branch tips. The species further separate in their use of common habitat due to differences in the timing of their reproductive season. These patterns of habitat use suggest that the degree of sociality can enable otherwise similar species to differ from one another in ways that may facilitate their co-occurrence in a shared environment, a possibility that deserves further consideration.

In the social behaviour of arthropods, regurgitation (feeding of the young) is a component of maternal care. In this paper, we describe regurgitation under laboratory conditions in species that share the same habitat, one subsocial (Anelosimus baeza) and a species considered to be solitary (Anelosimus nigrescens). The recently emerged spiderlings were fed by five of the nine A. baeza and six of the eight A. nigrescens females. In both species, the mother is critical in the initial stages, as spiderlings cannot feed themselves until the second instar. Our data suggest that A. nigrescens may be a subsocial species; this is the first report of regurgitation in these species. This fact shows the importance of regurgitation contributing to cooperation in live spiders. Future studies on maternal behaviour in these species are needed to elucidate the degree of sociality. [ABSTRACT FROM AUTHOR]