o 55'W), Atlantic Forest, was studied in ten colonies, and in two periods: from July to September 1993 and from August to September 1995. The colonies were grouped in weak, medium and strong, according to the diameter of the combs, which can provide a good idea of the number of cells built. 855 observations were accomplished for 5 minutes, every half-hour, from 8 to 18 hours. The total number of bees that entered and left the hive and the number of bees that arrived with mud, pollen and resin, besides the number that went out with debris in that period were counted. It was also registered the temperature and the relative humidity of the air. The total external activity, as well as pollen collection, was maximum in the first hours of the morning, mainly in strong colonies. Weak colonies moved their maximum activity approximately to 12 hours. Pollen collection declined gradually, while mud and resin collection rose; removal of debris was greater in the beginning of the morning and in the end of the afternoon. Flight activity increased as relative humidity of the air rose, being optimum for strong colonies in the range between 80%-89%, and for the weakest colonies between 70%-79%. The minimum temperature observed for exit of the bees was 11 o C, with optimum temperatures ranging between 17 o C and 22 o C. The results showed that the general state of the colony influences the different strategies of food collection and that these bees should be adapted to environments of high relative humidity as the Atlantic forest.Key words: stingless bees, flight activity, climate conditions, resource collection. RESUMOA influência do estado da colônia na atividade de vôo do meliponíneo Melipona bicolor bicolor Lepeletier (Apidae, Meliponinae)A atividade de vôo de Melipona bicolor bicolor, proveniente de Cunha (23 o 05'S, 44 o 55'W), Mata Atlântica, foi estudada em dez colônias, em dois períodos: de julho a setembro de 1993 e de agosto a setembro de 1995. As colônias foram agrupadas em fracas, médias e fortes, segundo o diâmetro dos favos de cria, que pode fornecer uma idéia do número de células de cria construídas. Foram realizadas 855 observações durante 5 minutos, a cada meia hora, das 8 às 18 horas, quando era contado o número total de abelhas que entravam e saíam, o número de abelhas que chegava com barro, pólen e resina, além do número que saía com detritos das colméias naquele período. Foram também registradas a temperatura e a umidade relativa do ar. A atividade externa total, assim como a coleta de pólen, foi máxima nas primeiras horas da manhã, principalmente nas colônias fortes. Colônias fracas deslocaram a atividade máxima para as 12 horas, aproximadamente. A coleta de pólen declinou gradualmente,

Flight activity of Plebeia pugnax Moure (in litt.) was studied in six colonies coming from Cunha, SP, from July to October 1994. Twice a week, from 8:00 a.m. to 6:00 p.m., for 5 minutes every half-hour, all the bees entering and leaving the hives were counted. Six hundred counts were made and the materials that foragers carried were recorded. Data were analysed in relation to temperature, relative humidity, light intensity and day time. Foragers' flight activity was relatively constant in a wide range of temperature, from 22 o C to 34 o C. The minimum temperature for the beginning of flight activity was 14 o C. Effective flight activity (when foragers of all colonies were leaving the hives) occurred at 15 o C. These bees also flew within a wide range of relative humidity, from 30% to 100%, decreasing slowly after 50%. Flight activity increased as light intensity rose and it has also increased as the hours passed by, reaching a peak around midday and decreasing gradually afterwards. Pollen was collected all day long, while resin collection was relatively constant and debris transportation was slightly higher after 10:00 h. From all known Plebeia species, this one flew on the lowest temperature ever registered for this genus.Key words: flight activity, stingless bees, climatic factors. C. Estas abelhas também voaram em uma ampla faixa de umidade relativa, de 30% a 100%, diminuindo paulatinamente acima de 50%. A atividade de vôo aumentou ao mesmo tempo em que a intensidade luminosa elevou-se e esta também aumentou com o passar das horas, alcançando um pico ao redor do meio-dia e decrescendo gradualmente depois. Foi coletado pólen ao longo de todo o dia, enquanto a coleta de resina foi relativamente constante e o transporte de detritos foi ligeiramente superior depois das 10 h. De todas as espécies de Plebeia conhecidas, esta voou na temperatura mais baixa já registrada para esse gênero. RESUMOPalavras-chave: atividade de vôo, meliponíneos, fatores climáticos. Rev. Brasil. Biol., HILÁRIO, S. D., IMPERATRIZ-FONSECA, V. L. and KLEINERT, A. de M. P.

Colonies of the Brazilian stingless bee Plebeia remota show a reproductive diapause in autumn and winter. Therefore, they present two distinct reproductive states, during which colony needs are putatively different. Consequently, foraging should be adapted to the different needs. We recorded the foraging activity of two colonies for 30 days in both phases. Indeed, it presented different patterns during the two phases. In the reproductive diapause, the resource predominantly collected by the foragers was nectar. The majority of the bees were nectar foragers, and the peak of collecting activity occurred around noon. Instead, in the reproductive phase, the predominantly collected resource was pollen, and the peak of activity occurred around 10:00 am. Although the majority of the foragers were not specialized in this phase, there were a larger number of pollen foragers compared to the phase of reproductive diapause. The temperature and relative humidity also influenced the foraging activity.

Through an automated system, foragers' flight activity of four colonies of Plebeia remota was registered at same time from December 1998 to December 1999. The large amount of data obtained allowed a quantitative and seasonal analysis of the effect of speed and direction of wind on their flight activity. In all four seasons, the smallest flight activity of Plebeia remota occurred when there was no wind or when the wind speed average was below 0.5 m/s. The flight activity peaks occurred in higher measured wind speeds and varied according to the seasons and the colonies. In the summer, the flight activity peaks occurred between 3.5 and 5.5 m/s of speed, in the autumn, in the series 4.0-4.5 m/s, and in the spring between 4.5 and 6.0 m/s. In the winter, clear restriction upon flight activity occurred in wind speeds above 5.5 m/s. Plebeia remota foragers guided preferentially their flights for certain wind directions. Except summer, the directions were similar to the four colonies. These directions matched with the locations where the most used floral resources are. On the other hand, lowest flights number coincided with conditions when the foragers would left their colonies upwind.Keywords Através de um sistema automatizado, a atividade do vôo de forrageiras de quatro colônias de Plebeia remota foi registrada, simultaneamente, de dezembro de 1998 a dezembro de 1999. A grande quantidade de dados obtidos permitiu uma análise quantitativa e sazonal do efeito da velocidade e direção do vento sobre a atividade de vôo. Nas quatro estações, a menor atividade de vôo de Plebeia remota ocorreu quando não houve vento ou quando a velocidade média do vento esteve abaixo de 0,5 m/s. Os picos de atividade de vôo ocorreram em velocidades de vento maiores e variaram segundo as estações e as colônias. No verão, os picos de atividade de vôo estiveram entre 3,5 e 5,5 m/s de velocidade, no outono, na classe 4,0-4,5 m/s, e na primavera entre 4,5 e 6,0 m/s. Entretanto, no inverno, houve clara restrição da atividade externa sob velocidades de vento superiores a 5,5 m/s. As forrageiras de P. remota orientaram preferencialmente seus vôos para certas direções de vento. Exceto no verão, as direções predominantes de vôo foram similares entre as quatro colônias. Estas direções também coincidiram com a posição dos recursos florais mais utilizados pelas colônias. Quando as forrageiras tinham que sair da colônia com vento contra, se registrou menor atividade de vôo.Palavras-chave: atividade de vôo, abelhas sem ferrão, fatores climáticos, vento, forrageio.