ECOLOGY, BEHAVIOR AND BIONOMICS Floral Preferences and Climate Infl uence in Nectar and Pollen Foraging by Melipona rufi ventris Lepeletier (Hymenoptera: Meliponini) in Ubatuba, São Paulo State, Brazil

We describe the environment effects on the amount and quality of resources collected by Melipona rufi ventris Lepeletier in the Atlantic Forest at Ubatuba city, São Paulo state, Brazil (44o 48’W, 23o 22’S). Bees carrying pollen and/or nectar were captured at nest entrances during 5 min every hour, from sunrise to sunset, once a month. Pollen loads were counted and saved for acetolysis. Nectar was collected, the volume was determined and the total dissolved solids were determined by refractometer. Air temperature, relative humidity and light intensity were also registered. The number of pollen loads reached its maximum value between 70% and 90% of relative humidity and 18 oC and 23oC; for nectar loads this range was broader, 50-90% and 20-30oC. The number of pollen loads increased as relative humidity rose (rs = 0.401; P < 0.01) and high temperatures had a strong negative infl uence on the number of pollen loads collected (rs = -0.228; P < 0.01). The number of nectar loads positively correlated with temperature (rs = 0.244; P < 0.01) and light intensity (rs = 0.414; P < 0.01). The percentage of total dissolved solids (TDS) on nectar loads positively correlated with temperature and light intensity (rs = 0.361; P < 0.01 and rs = 0.245; P < 0.01), negatively correlated with relative humidity (rs = -0.629; P < 0.01), and it increased along the day. Most nectar loads had TDS between 11% and 30%, with an average of 24.7%. The volume measures did not show any pattern. Important pollen sources were Sapindaceae, Anacardiaceae, Rubiaceae, Arecaceae, Solanaceae and Myrtaceae; nectar sources were Sapindaceae, Fabaceae, Rubiaceae, Arecaceae and Solanaceae.