Male orchid bees (Hymenoptera: Apidae: Euglossini) in canopy and understory of Amazon Várzea Floodplain forest. I. Microclimatic, seasonal and faunal aspects

Abstract

Floodplain forests are important ecosystems of the Amazon Basin. The aim of the present study was to investigate whether male orchid bees have preference for arboreal strata in a forest with a dynamic understory. Traps with aromatic scents to attract bees were placed at heights of 25 m and 1.5 m. Data loggers were used to register temperature and relative humidity at both heights. A total of 835 individuals belonging to 28 species were sampled, 645 males of 23 species in the understory and 190 males of 24 species in the canopy. The temperature was 1.4 0C higher in the canopy and the air relative humidity was 11.58% higher in the understory. Temperature, relative humidity and winds were the most important abiotic variables influencing the assemblage in the canopy. The abundance increased in the understory and decreased in the canopy in the less rainy season. Euglossa cognata Moure, Eulaema meriana Olivier and Euglossa ignita Smith were species closely associated with strata and seasons. The present study revealed higher richness and abundance in the understory all months of the year, reinforcing the likelihood that orchid bees forage preferably in the lower layer of rainforests.