Nest architecture and nesting ecology of the orchid bee Eulaema meriana (Hymenoptera: Apinae: Euglossini)

The orchid bees (Euglossini), found only in the New World tropics, are among the most spectacular of the bees, with their relatively large size, brilliant metallic coloration and exceptionally long tongues thought to have evolved as an adaptation for nectar collection from long-corolla flowers. In spite of their flamboyant appearance they are exceedingly difficult to study in nature, and therefore most aspects of their biology are little understood. Here we present new data on the nest structure and nesting ecology of Eulaema meriana (Olivier), one of the largest and most widely distributed of the orchid bees. We describe a method for observing field nests in situ, which enabled us to examine the process of construction of six nests found in the Amazonian region of Ecuador. We study the foraging activity patterns and array of resources brought to the nest by females engaged in brood-cell construction and provisioning, and we investigate the time expenditures and time course for cell construction, larval provisioning and oviposition. We also provide a list of the natural enemies reared or collected from the nests. Our observations suggest that there may be considerable plasticity in the social organization of E. meriana, ranging from small single-female nests to large nests with more than one female and a possible division of labor. These observations of E. meriana provide a framework for comparison with other species of Eulaema in an evolutionary context.