Abelhas (Hymenoptera) visitantes florais de Vernonia polyanthes less (Asteraceae)

Abstract

The bees are constantly used in studies in order to assess biodiversity, since they are sensible to environmental and climatic changes. Many of these studies include exotic species such as Apis mellifera scutellata (Africanized bees). However, the literature shows no agreement on the impact provoked by Africanized bees or on the resource limitation for native species and the destabilization of biologic communities. Some botanic species are fundamental to the maintenance of bee communities, especially during resource shortage. In this context, we may highlight Vernonia polyanthes, popularly known as “Assa-peixe”, widely used in apiculture and honey production. Apiculture, or bee-keeping, is an economic activity which rationally explores the products made by Apis bees. Much of the Brazilian apiculture is carried out by family farmers in small and medium size productions, which commercialize many products and small animals. In spite of this activity, it is not known whether apiculture interferes on bee communities due to the introduction of Africanized bee hives (and consequent increase in the biomass of this exotic species). The knowledge on the species of bees visiting V. polyanthes inflorescences and possible impact caused by family apiculture is not yet fully elucidated. Therefore, this thesis aimed to understand the interactions and behaviors shown by bees in V. polyanthes inflorescences, identify the flower-visiting bee fauna and also to verify the impact of apiculture upon the native bee community. The research was carried out in two localities in the countryside of Valença, Rio de Janeiro, and only one of them had an apiary. Samples were held at a weekly basis during the flowering period of V. polyanthes, from July to August (winter) of 2012 and 2013, in 10-minutes sessions for each hour in the study period (from 09:00 to 16:00), totaling 1600 minutes of samples. We recorded 1434 (60.43%) individuals in the locality with the apiary and 934 (39.57%) in the one without the apiary, totaling 2373 individuals distributed in 19 species, most of them being common to both communities (n= 15; 78.95%). Worker visitations occurred from 09:00 to 16:00, with increased activity between 11:00 and 15:00. Among the abiotic factors, relative humidity of air (rs= -0.691; p< 0.0001) and temperature (rs= 0.531; p< 0.0001) were correlated to the foraging activity. The hottest hours of day (high temperature and low humidity) concentrated the 11 greatest bee foraging frequencies (46.9%). We observed a significant difference in abundance (t (1; 19) = 2.140; p= 0.046) between the studied localities. Regarding richness, there was no significant difference (t (1; 19) = -0.600; p= 0.555) between localities. The nectar volume, as well as a high concentration of sugar in V. polyanthes, might be easing the effects of competition between the bee species due to a great offer of food resources. That botanic species stands out as a good alternative for beekeepers to enhance their productivity, generating wealth without significantly impact the richness and diversity of bees, thus being a good model for environmental projects due to its sustainability.