ABSTRACT
Adenocalymma bracteatum is a shrub of dense foliage and yellow flowers, easily found on grasslands areas in Central Brazil. The aim of this study was to determine the reproductive biology and the flower visitors of A. bracteatum in a pasture area nearby Ivinhema city, MS (Brazil). The flowering peak occurs in winter. The flower reflects ultraviolet light. Anthesis begins at 6:30h, and pollen and nectar are the resources to visitors. We captured 1,038 floral visitors. The bees Apis mellifera (L.), Trigona sp., Trigona spinipes (Fabricius), (Hymenoptera: Apoidea) and the ant Cephalotes sp. (Hymenoptera: Formicidae) were the main visitors. The reproductive tests indicate that A. bracteatum is self compatible, justifying its expansion in altered environments; however, the largest reproductive success was dependant on cross-pollination and self-pollination, evidencing the pollinators importance. Adenocalymma bracteatum presents melittophilous syndrome and bumblebees were the main pollinators in the area. The correlations observed between the climatic variables and the main pollinator species were low or medium.
Subject(s)
Animals , Bignoniaceae/physiology , Flowers , Insecta , PollinationABSTRACT
Realizaram-se estudos sobre as formas de reprodução de Stenolobium stans (Juss.) Seem e determinou-se a diversidade, freqüência e constância dos insetos visitantes nas flores em diferentes horas, durante quatro anos. As flores de S. stans começam a se abrir nas primeiras horas do dia entre 5 e 6h, com duração de 3 a 8h. Quando o estigma está receptivo, o pólen tem 90 por cento de viabilidade. Além do pólen, a flor possui outros atrativos para os insetos visitantes, ou seja, os osmóforos responsáveis pelo odor adocicado, luz ultravioleta refletida e néctar com 25 por cento de açúcar. A planta é autocompatível, reproduzindo-se por autogamia, geitonogamia ou xenogamia o que determina a necessidade de polinizadores externos e justifica ser a espécie vegetal em estudo uma séria invasora de campos e pastagens. Grande diversidade de insetos foi verificada visitando as flores, com predominância das abelhas. Os polinizadores foram Centris collaris Lepeletier, Bombus morio (Swederus), Eulaema nigrita Lepeletier e Epicharis sp. No meio rural houve menor incidência das espécies nativas do que no ambiente urbano, com predominância da abelha introduzida Apis mellifera L. Fatores ambientais, principalmente a temperatura, luminosidade, umidade relativa do ar e velocidade do vento, influenciaram a atividade forrageadora dos insetos.
Studies on the different ways of reproduction of Stenolobium stans (Juss.) Seem and on the diversity, frequency and constancy of flower-visiting insects at different hours were carried out during four years. The S. stans flowers open between 5 and 6 am during 3 to 8h, with 90 percent pollen viability. Besides the pollen, the flower has other features that are attractive to the visiting insects, like osmophores responsible for a sweet odor, ultra-violet reflected light and nectar at 25 percent of sugar. The plant is autocompatible and reproduces by autogamy, geitonogamy or xenogamy. This behavior demands external pollination and justifies the species to be a serious invasor of grounds and pastures. Large diversity of insects were observed visiting the flowers, with predominance of bees. The pollinators species were Centris collaris Lepeletier, Bombus morio (Swederus), Eulaema nigrita Lepeletier and Epicharis sp. The incidence of native species was lower at the rural area than at the urban one, with predominance of the exotic Apis mellifera L. The environmental factors, mainly temperature, light, relative humidity and wind speed, influenced the foraging activity of the insects.