RESUMO
Communication between plants and nocturnal pollinators in low light conditions is mainly guided by floral scents, which is well documented for plants pollinated by bats, moths, and beetles. Just recently, nocturnal bees have been added to the list of pollinators known to respond to floral scents of their host plants. Little is known about the floral scent chemistry of plants visited and pollinated by nocturnal bees. Among these plants are economically important fruit crops of the family Myrtaceae. We aimed to analyze the nocturnal floral scent profiles of 10 species of Myrtaceae (only diurnal P. cattleianum was sampled after sunrise) and address the following questions: i) What are the main floral scent compounds emitted by the species? ii) Are the floral scent profiles similar to those described for other species pollinated by nocturnal bees? Floral scents were collected by dynamic headspace and analyzed by GC-MS (gas chromatography - mass spectrometry). The total amount of scent trapped ranged from 74 ng/flower/hour for Syzygium malaccense to 7556 ng/flower/hour for Eugenia dysenterica. A total of 46 floral scent compounds were detected in the samples with the most abundant compounds being the aromatics benzaldehyde, benzyl alcohol, 2-phenylethanol, methyl salicylate, 2-phenylethyl acetate, and benzyl acetate; the aliphatic compound 1-octanol; and the monoterpene linalool. The different species exhibited different relative scent patterns. Overall, the nocturnal scents of the studied species of Myrtaceae are dominated by aromatic compounds, which is in contrast to the scent profiles described for other plants pollinated by nocturnal bees.
Assuntos
Flores/química , Frutas/crescimento & desenvolvimento , Myrtaceae/química , Myrtaceae/crescimento & desenvolvimento , Odorantes/análise , Fatores de TempoRESUMO
Schefflera arboricola (Hayata) Merr (Araliaceae) é uma planta exótica, porém amplamente cultivada no Brasil para ornamentação. Devido à abundância de flores que produz, esta árvore é altamente atrativa para abelhas Apis mellifera, bem como para diversos meliponíneos nativos. S. arboricola oferece aos seus visitantes florais pólen e néctar, que são disponibilizados ao amanhecer. A. mellifera possui ampla vantagem na coleta desses recursos devido à sua capacidade de forragear mais cedo do que os meliponíneos de pequeno e médio porte. Através de experimentos de exclusão verificou-se que as abelhas nativas mudam seu comportamento nas flores de S. arboricola em função da competição. Quando A. mellifera compete pelos mesmos recursos florais, as abelhas Scaptotrigona visitam três vezes mais flores e mudam o recurso preferencialmente coletado, pois passam a coletar pólen ao invés de néctar. Os dados obtidos sugerem que A. mellifera pode estar interferindo na dinâmica de forrageamento das abelhas Scaptotrigona.
Schefflera arboricola Hayata Merr (Araliaceae) is an exotic plant widely cultivated in Brazil for ornamental purposes. Their flowers are very attractive to Africanized honey bees (Apis mellifera) as well to several native Meliponini bees. Therefore, it is an interesting plant to test the competitive interactions and foraging overlapping among Africanized honey bees and native stingless bees. S. arboricola offers pollen and nectar to their visitors, which become available early, in the morning. A. mellifera has a large advantage in resource harvesting since can forage earlier than smaller stingless bees. By means of an exclusion experiment, it was verified that the behaviors of native bees change when they are visiting S. arboricolas flowers in the presence of A. mellifera. When Scaptotrigona and A. mellifera are partitioning this flower resource, Scaptotrigona bees visited three times more flowers and changed the resource preference from nectar to pollen. In this context, A. mellifera may be interfering in the foraging dynamics of native Scaptotrigonabees.