Diversity and Temporal Variation in the Orchid Bee Community (Hymenoptera: Apidae) of a Remnant of a Neotropical Seasonal Semi-deciduous Forest

Multiple biotic and abiotic variables control the composition, diversity, and temporal fluctuations of insect communities. In particular, the assembly of bee communities is strongly influenced by climatic factors as well as variation in food resource availability, which in turn also fluctuates in response to the same factors. The goal of the present study was to investigate the species composition, the species richness and the abundance of the euglossine bees in a remnant of the seasonal semi-deciduous forest of northeastern São Paulo state, and evaluate the temporal variation in those parameters over time. From January to December 1990, males of euglossine bees were sampled using three aromatic baits. We collected 643 males belonging to 12 species and three genera. Euglossa imperialis Cockerell was the most abundant species, followed by Eulaema nigrita Lepeletier and Euglossa melanotricha Moure. The composition and species richness showed temporal variation throughout the year, with the highest values being observed during the rainiest months. Such variations occurred by the presence of males from six species which were sampled only during the rainiest months. Of the five most abundant species, Eg. imperialis and Eg. melanotricha were the only species sampled throughout the year. Only El. nigrita and Eg. melanotricha, had the monthly abundance of males correlated with precipitation. Based on the assumption that male euglossine capture rates reflect actual abundance at the sampled habitats, we believe that Eg. imperialis, usually represented by few male in other studies, has a population very well established in the habitat here studied

Multifemale nests and social behavior in Euglossa melanotricha (Hymenoptera,Apidae, Euglossini)

The nesting biology and social behavior of the euglossine bee species Euglossa melanotricha was analyzed based on the monitoring of eight nests found in man-made cavities and transferred to observation boxes. Euglossa melanotricha females usually construct their nests in cavities in the ground, in buildings, or in mounds. In this study, we present new data on the nesting biology of E. melanotricha. The process of reactivation of nests was commonly observed with one to three females participating in the reactivation. The duration of the process of reactivation ranged from 10 to 78 days (n = 31) and were longer during the rainy season. Time spent (in days) for provisioning, oviposition and closing a single cell was higher in reactivations that occurred during the dry period. 151 emergences were observed (39 males and 112 females). 90 (80.3%) of the emerged females returned to the natal nest, but only 35(38.9%) remained and actively participated in the construction and provisioning of cells. The other 55 abandoned the nests after several days without performing any work in the nest. Matrifilial nest structure was regulated by dominance-subordinate aggressive behavior among females, where the dominant female laid almost all eggs. Task allocation was recognized by behavioral characteristics, namely, agonism and oophagy in cells oviposited by other females. Euglossa melanotricha is multivoltine and its nesting is asynchronous with respect to season. Our observations suggest a primitively eusocial organization. These observations of E. melanotricha provide valuable information for comparison with other species of Euglossa in an evolutionary context.Brazilian National Research Council (CNPq)Brazilian National Research Council (CNPq)Fapesp [2010/10027-5]FAPES