Ecologia da polinização e análise da composição química do óleo floral de duas espécies de Mouriri (Melastomataceae) e sua importância na atração dos visitantes florais

Abstract

Mouriri (Melastomataceae, Memecyloideae) is a Neotropical genus with 85 species with "Buzz pollination". Although, to be its main attractive pollen floral, concave and elliptical glands located in the back of the anthers and called elaiophor are responsible for the production of oil. The present study aimed to study two species of Mouriri about phenology, floral biology, visitors, and chemical identification systems of floral oils. Fortnigtly (n = 10 individuals) were observed from June/2013 to June/2014 (M. acutiflora) and December/2013 to March/2015 (M. guianensis). The bees were collected in January/2015 and February/2015 (M. guianensis) and in August/2015 (M. acutiflora). Open pollination, self-pollination manual, spontaneous selfpollination cross-pollination and apomixis were applied to the reproductive systems. Floral glands (n = 1800) and legs of bees [(Centris (Centris) caxiensis Ducke (n = 6), Melipona (Melikerria) fasciculata Smith (n = 10) and M. (Melipona) subnitida Ducke (n = 10)] were subjected to extraction with hexane, methyl and analyzed by GC/MS. Mouriri acutiflora flowering from April to September and fruits from June to November and M. guianensis blooms from September to March and fructifies from November to March. The species are selfcompatible, not apomitcs, although still present reliance on pollinators. A total of 141 visitors were observed in M. acutiflora, and M. fasciculata (59.79%), C. caxiensis (12.31%) and Eulaema (Apeulaema) nigrita Lepeletier (9.4%) bees had the highest percentages, representing 81.5% of the total visits. In M. guianensis 86 individuals were recorded, mainly Xylocopa (Neoxylocopa) cearensis Ducke (60%), M. subnitida (21.17%) and Megalopta (Amoena) amoena Spinola (9.41%) representing 98.58% of all visits. The pollen was predominantly resource harvested through the mechanism of vibration (Buzz pollination), although the floral oil also has been available in both species. Melipona subnitida used only the regions of the glands of M. guianensis for seal/protect of the entrance of the colony, indicating a possible use of the glands/oil. Visitors, except Augochlopsis sp., Trigona sp. and wasps (Chalcidoideae) are pollinators of Mouriri. The substances identified by GC/MS in floral oils were mainly palmitic acids, stearic, oleic, lignoceric and palmitoleic, in the form of their methyl esters. The extracts of the legs of the bees had as main substances linoleic acid, stearic, oleic, palmitic acid and alcohol hexacosanol. Methyl hexadecanoate and methyl octadecanoate were common to the floral oils and extracts of the legs of the bees, indicating possible harvest of the lipids. Thus, Mouriri confers a regular supply of resources to the pollinators, floral oil and pollen, this being the primary resource harvested by bees.