São Paulo. 20520 -São Paulo -Bra sil.(recebido em 26.X . 1982)RESUMO -A produção de machos em Nannotrigona (Scaptotrigona) postiça e alguns aspectos correlacionados foram investi gados e os resultados mostram que os fatores extrínsecos co mo temperatura e precipitação, através da sua importância na determinação das floradas e subsequente aumento na disponibi^ lidade de mel e pólen, não são fatores determinantes imedia tos da alta produtividade da colônia e da produção de machos, como consequencia. Os dados também sugerem uma ausência de inibição da rainha no desenvolvimento ovariano das operárias e que a produção de machos ocorre independentemente da idade fisiológica da rainha. £ possível que muitos outros fatores intrínsecos como alta densidade populacional da colônia (pro vavelmente conseqüente de condiçoes favoráveis de estoque de polen e mel) sejam mais importantes na determinação da produ ção de m a c h o s , uma vez que colônias que apresentam uma baixa densidade populacional não produzem machos, embora os ovários das operárias estejam sempre desenvolvidos. Além disso, a produção de machos parece estar ligada â oviposição das o-perárias^ devido â relação existente entre ocorrência de^ma chos e células de cria contendo mais do que um ovo por célu la, numa mesma colônia.ABSTRACT -The production of males in Nannotrigona (Soaptotrígona) postioa and some related aspects were investigated, and the results show that the extrinsic factors, such as tern perature and precipitation, through their importance in flowering and subsequent increase in the availability of ho ney and pollen do not immediately determine high colony pro ductivity and production of males. The data also suggest an absence of queen inhibition in the ovarian development of the workers, and that male production occurs irrespective of the queen's physiological age. It is possible that many other intrinsic factors , such as high populational density of the colony (probably a consequence of favorable conditions for storage of pollen and honey) are more important in determining male production, since colonies presenting a low populational density do not produce males, although the ova ries of the workers are always developed. Besides, the production of males seens to be related to workers oviposition, due to the relationship between the occurrence of males and brood cells containing more than one egg for each cell in the same colony

The pollination effectiveness of the stingless bee Melipona quadrifasciata and the honey bee Apis mellifera was tested in tomato plots. The experiment was conducted in four greenhouses as well as in an external open plot in Ribeirão Preto, SP, Brazil. The tomato plants were exposed to visits by M. quadrifasciata in one greenhouse and to A. mellifera in another; two greenhouses were maintained without bees (controls) and an open field plot was exposed to pollinators in an area where both honey bee and stingless bee colonies are abundant. We counted the number of tomatoes produced in each plot. Two hundred tomatoes from each plot were weighed, their vertical and transversal circumferences were measured, and the seeds were counted. We collected 253 Chrysomelidae, 17 Halictidae, one Paratrigona sp, and one honey bee from the flowers of the tomato plants in the open area. The largest number of fruits (1414 tomatoes), the heaviest and largest tomatoes, and the ones with the most seed were collected from the greenhouse with stingless bees. Fruits cultivated in the greenhouse with honey bees had the same weight and size as those produced in one of the control greenhouses. The stingless bee, M. quadrifasciata, was significantly more ef-©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 8 (2): 751-757 (2009) S.A. Bispo dos Santos et al. ficient than honey bees in pollinating greenhouse tomatoes.

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It is known the importance of bees as pollinators and visiting of flowers in the most world's ecosystems and the special role that stingless bees play in the tropical areas (Roubik, 1989; Biesmeijer & Slaa, 2006). Bees are also known to be efficient pollinators of many crops as about 30% of human food is derived frombee-pollinated crops (reviewed in Slaa et al., 2006). Unpredictable environmental changes affect foraging activities in terms of timing and location of food. There are two main features regulating departure of foraging bees: individual memory and threshold response to react to the foraging stimuli (internal factors), and environmental and colony conditions which determine the level of exposure to stimuli associated with decision to forage (external factors) (Biesmeijer & de Vries, 2001). Colonies of honey bees and stingless bees can allocate more foragers to collect nectar and pollen in response to the amount of food in storage and Abstract Stingless bees play an important role in Tropical and Subtropical ecosystems as pollinators of many plants. The aim of this study was to characterize the pattern of flight activity and foraging for pollen by Scaptotrigona depilis workers and their relation with climatic and temporal factors. We observed flight activity from July 2001 to June 2002 and pollen collection by scoring the flow of workers entering and exiting the colonies. We tested whether environmental (temperature, relative humidity, pluviosity and luminosity) and temporal predictors (month and time of day) affected bees' activities. The study was conducted during one year and the records of observations showed that during the dry season when the length of light is longer, the external activity was more intensive, while during cold months with shorter light period, foraging activity was reduced. Pollen collection showed a peak in February, but in general this activity was regulated by temperature, humidity and daily luminosity.

Caste fate conflict is expected in Melipona bees because queens and workers are the same size and are reared in identical sealed cells. Extrinsic and intrinsic colonial factors, however, seem to have limiting effects on queen production. The consequences of colonial conditions on both queen and worker production, particularly the effects of food storage in the colonies, are still poorly understood. Here, we investigated whether caste production in seven natural colonies of Melipona compressipes fasciculata was affected by food resources, seasonal factors, or internal factors. The results showed that, at the populational level, about 5 % of the females developed into gynes; in the strongest colony, 12.7 % of the females developed into gynes. Male production was verified only in stronger colonies. We suggest that caste ratio is primarily affected by intra-colonial conditions rather than by food resources.