Abelhas visitantes florais em um fragmento de floresta estacional semidecidual em Uberlândia-MG

Abstract

Studies of bees dynamics on ecosystems are important for understanding the diversity of populations and interactions between species. The bees seek in plants the resources needed to survival, such as pollen, nectar, oil and resin. Also, are the most effective pollinators of native plants, playing an important role in maintenance of forests. Bee-plant interactions networks can provide useful information for conservation and management of pollinators. The study of the bees guild is a starting point for understanding the community structure, still allowing the knowledge of other environmental aspects such as resources partition and competition. This study aimed to identify and build the bee-plant interactions network, in a Semideciduous Forest (SF) fragment in Uberlândia and study the guild structure of flower-visiting bees of the most attractive plant at the same location. Bees were collected with entomological nets on flowers in a 200m transect at forest edge and sacrificed in a chamber with ethyl acetate. Temperature and relative umidity were recorded hourly using a digital thermo-hygrometer. In the first stage, the study was conducted between October 2010 and September 2011, monthly, from 8h00 AM to 2:30 PM. In the second stage, samples were collected between April and June 2012 and 2013, for an hour and a half each day sampled, during the activity period from 7h00 AM to 5:30 PM. The NODF index of the bee-plant interactions network and betweenness centrality was calculated. In the second stage, bees were measured with a digital caliper and classified into 5 size classes. To analyze the temporal partition of floral resources by bees visiting the most attractive plant, the Kruskal-Wallis test was performed between the most abundant species for each horary and between the size class and bee abundance for each of the sampled horary. To analyze the bees activity foraging throughout the day, we did an Analysis of Variance (ANOVA) between bee abundance and the visit horary. The Kruskal-Wallis test was also conducted between the bees size class and their abundance throughout the study. The interactions network was nested (NODF = 10.97 , p = 0:03) and composed of 67 bee species and 25 plant species, and the bee and plant species that had higher centrality were Apis mellifera and Merremia macrocalyx respectively. In the second stage of this study, we found 55 bee species visiting the most attractive plant (M. macrocalyx) at the site. Abundance differed significantly between visiting hours (F = 7.415 , p < 0.001 ) and between size classes (H = 112,245 , p < 0.001), but there was no temporal partition. The bee-plant interactions network generated is nested, which gives it stability, demonstrating its importance for the fragment conservation. Merremia macrocalyx proved to be an important species in the attractiveness of bees, performing a key role in maintaining the community.