Understanding how and why exotic species use their habitats is crucial for defining effective conservation strategies. We aimed to investigate habitat use by an exotic population of squirrel monkeys living in an Atlantic Forest fragment and identify factors associated with their habitat preferences. Over 6 months of scan sampling observations, we collected data on native and exotic plants consumed by the squirrel monkeys, food availability, and interactions between the squirrel monkeys and the native common marmosets. We also georeferenced the estimated centroid point of the study group during each scan. Squirrel monkeys used Secondary Old Forest habitats more often than the other habitats available. The consumption of native and exotic plants and the association with common marmoset appear to have influenced the habitat use of the exotic squirrel monkeys; however, the choice habitat did not demonstrate to be associated with food availability. The exotic squirrel monkeys preferred to use less disturbed habitats to consume a high amount of food (often associated with the common marmoset), potentially optimizing their food intake. Our findings demonstrated the adaptive success of an exotic primate in its non-natural habitat and the key role of the plant community in maintaining this population.

Tenuisvalvae notata (Mulsant) (Coccinellidae) is a predatory ladybird beetle native to South America. It specializes in mealybugs prey (Pseudococcidae), but relatively little is known about its ecology. In contrast, the ladybird beetle Cryptolaemus montrouzieri Mulsant (Coccinellidae) is indigenous to Australia and has been introduced to many countries worldwide including Brazil for biological control of mealybugs. The potential impacts of these introductions to native coccinellids have rarely been considered. The software CLIMEX estimated the climate suitability for both species as reflected in the Ecoclimatic Index (EI). Much of South America, Africa, and Australia can be considered climatically suitable for both species, but in most cases, the climate is considerably more favorable for C. montrouzieri than T. notata, especially in South America. The CLIMEX model also suggests seasonal differences in growth conditions (e.g. rainfall and temperature) that could affect the phenology of both species. These models suggest that few locations in South America would be expected to provide T. notata climatic refugia from C. montrouzieri. Although other ecological factors will also be important, such as prey availability, this analysis suggests a strong potential for displacement of a native coccinellid throughout most of its range as a consequence of the invasion by an alien competitor.

There are several possible causes of aggregated nesting in solitary Aculeata, one being joint defense against parasites. We tested whether females prefer nesting in aggregations, even if they consist of heterospecifics. We compared the colonization and nesting parasitism of trap-nests with and without a red mason bee aggregation. The results did not support our hypothesis that females prefer nesting in aggregations. The numbers of wild Aculeata nests did not differ between trap-nests with and without an aggregation. Unexpectedly, parasitism rates were higher in trap-nests with aggregations. When analyzing only nests of wild insects (mostly wasps), the differences in parasitism disappeared. Natural nesting sites may be such a limited resource that females nested in the first trap-nest they encountered and did not discriminate between our treatments, or wasps might share too few parasites species with bees to benefit from joint nest defense.