RESUMO
Battus polystictus (Butler) is a butterfly from the Neotropical region, occurring in the Atlantic Forest and Pampa biomes. It is commonly found in forest fragments surrounded by meadow formations, subjected to marked seasonal changes. Here, we report the population dynamics of B. polystictus at a high latitude environment and provide notes on its natural history. Population parameters were estimated on a 12-month mark-recapture program and the seasonality of resources investigated by exhaustive mapping of host-plants and flowers. The number of butterflies per day was not stable during the year, ranging from zero (winter) to 22 (summer); the sex ratio was always male biased (3M:1F). The age structure was not constant, with an increase of older individuals toward summer. The population density was positively correlated with temperature, relative humidity, and day length. The residence time was lower for males, while the vagility was lower for females; the increment of resources at forest edges seems to increase the likelihood of occurrence of both sexes. The results shown here suggest that South Brazilian populations of B. polystictus have high ecological demands for spring and summer conditions, avoiding winter in diapause.
Assuntos
Borboletas/fisiologia , Animais , Brasil , Feminino , Masculino , Densidade Demográfica , Dinâmica Populacional , Estações do AnoRESUMO
Aristolochic acids (AAs) are thought to be responsible for the chemical protection of the aposematic larvae Battus polydamas (L.) (Papilionidae: Troidini) against predators. These compounds are sequestered by larvae from their Aristolochia (Aristolochiaceae) host plants. Studying the role of the chemical protection of the second and fifth instars of B. polydamas against potential predators, we found that the consumption of larvae by the carpenter ant Camponotus crassus Mayr and young chicks Gallus gallus domesticus was dependent on larval developmental stage. Second instars were more preyed upon than fifth instars; however, the assassin bug Montina confusa Stål was not deterred by chemical defences of the fifth instar B. polydamas. Laboratory bioassays with carpenter ants and young chicks using palatable baits topically treated with a pure commercial mixture of AAs I and AAs II in concentrations up to 100 times those previously found in B. polydamas larvae showed no activity. Similar results were found in field bioassays, where palatable baits treated as above were exposed to the guild of predators that attack B. polydamas larvae and were also consumed irrespective of the commercial AA concentration used. These results suggest that the mixture of AAs I and AAs II have no defensive role against predators, at least against those investigated in the present work. Other compounds present in Aristolochia host plants such as O-glycosylated AAs; benzylisoquinoline alkaloids; and mono-, sesqui-, di-, and triterpenes, which can be sequestered by Troidini, could act as deterrents against predators.