RESUMO
Deforestation has dramatically reduced the extent of Atlantic Forest cover in Brazil. Orchid bees are key pollinators in neotropical forest, and many species are sensitive to anthropogenic interference. In this sense understanding the matrix permeability for these bees is important for maintaining genetic diversity and pollination services. Our main objective was to assess whether the composition, abundance, and diversity of orchid bees in matrices differed from those in Atlantic forest. To do this we sampled orchid bees at 4-mo intervals from 2007 to 2009 in remnants of Atlantic Forest, and in the surrounding pasture and eucalyptus matrices. The abundance, richness, and diversity of orchid bees diminished significantly from the forest fragment toward the matrix points in the eucalyptus and pasture. Some common or intermediate species in the forest areas, such as Eulaema cingulata (F.) and Euglossa fimbriata Moure, respectively, become rare species in the matrices. Our results show that the orchid bee community is affected by the matrices surrounding the forest fragments. They also suggest that connections between forest fragments need to be improved using friendly matrices that can provide more favorable conditions for bees and increase their dispersal between fragments.
Assuntos
Abelhas/classificação , Ecossistema , Florestas , Animais , Biodiversidade , Brasil , Conservação dos Recursos Naturais , Eucalyptus , MasculinoRESUMO
Eufriesea violacea (Blanchard) is a very seasonal euglossine species, more frequently found in the southern and southeastern regions of Brazil. A number of studies have revealed large variations in the abundance of males of this species present in Atlantic Forest remnants throughout both regions. In this paper, we report variations in the abundance of E. violacea males sampled in several forest patches of different sizes (ranging from 10 to 580 ha), and we propose that this species is possibly sensitive to the reduction in size of forest remnants. Surveys were carried out in nine forest remnants of Atlantic rainforest located in northern Paraná State, southern Brazil. Male euglossine bees were collected with an entomological net when visiting scent-baits, between 10:00 am and 1:00 pm, from October to December of 2001 and 2006. A total of 360 E. violacea males were captured in the nine forest fragments studied. The number of bees attracted to scent baits in each forest patch varied from zero to 261. A very high association (r = 0.993) was detected between the forest patch size and the visitation rate of E. violacea males at different sites, with the highest mean number of males visiting baits/sampling (43.5) being observed for bees from the largest forest remnant. Although alternative hypothesis should not be discharged for the decline in the abundance or absence of E. violacea in small forest patches, our results indicate that populations of this euglossine species need larger forest areas for existing.
Eufriesea violacea (Blanchard) é uma espécie de Euglossini bastante sazonal, de ocorrência mais frequente no Sul e Sudeste do Brasil. Vários estudos revelaram grandes variações na abundância de machos de E. violacea em remanescentes de Mata Atlântica dessas duas regiões brasileiras. Neste artigo, relatamos variações na abundância de machos de E. violacea de vários fragmentos florestais de tamanhos distintos (variando de 10 a 580 ha), e sugerimos que a espécie seja provavelmente sensível à redução no tamanho da área do fragmento florestal. As amostragens foram realizadas em nove remanescentes florestais de Mata Atlântica, localizados no Norte do Paraná, Sul do Brasil. Machos euglossíneos foram coletados com rede entomológica durante suas visitas às iscas-odores, entre 10:00h e 13:00h, de outubro a dezembro de 2001 e 2006. O total de 360 machos de E. violacea foi coletado nos fragmentos estudados. O número de abelhas atraídas às iscas em cada área variou de zero a 261 indivíduos. O tamanho do fragmento foi proporcionalmente relacionado (r = 0,993) à taxa de visitação de machos de E. violacea nas diferentes áreas, sendo que o maior número médio de machos (43,5) por amostragem foi observado para abelhas do fragmento florestal maior. Embora hipóteses alternativas para o declínio na abundância ou ausência de E. violacea em fragmentos florestais menores não devam ser descartadas, esses resultados indicam que populações de E. violacea necessitam de áreas florestais maiores para sua sobrevivência.