DIEL FORAGING PATTERNS OF MALE EUGLOSSINE BEES - ECOLOGICAL CAUSES AND EVOLUTIONARY RESPONSE BY PLANTS

Male euglossine bees (Euglossa, Eulaema, Exaerete) were censused in Suriname, Trinidad and Costa Rica. Fragrance foraging was initiated at c0700, peak activity occurred at 1100, and foraging ceased at 1430. For Euglossa at baits in Costa Rica, in the morning hours bees were affected directly and positively by air temperature, itself controlled by time of day and cloud cover. After 1100 hr bees responded directly to time of day and were not directly affected by air temperature or cloud cover. The diel pattern of bee activity may have affected the evolution of diel patterns of floral activity in plants pollinated by male euglossines. Dalechampia brownsbergensis, which is pollinated by male euglossine bees, presents floral rewards and is receptive for pollination in the morning and early afternoon when male euglossines are most active. Species most closely related to D. brownsbergensis, however, are pollinated by female euglossine bees and present floral rewards in the late afternoon. Census data and phylogenetic analysis suggest that D. brownsbergensis evolved morning presentation of the floral reward as a result of the shift to pollination by male euglossines. -from Authors