Reproductive biology in species of Bidens L. (Asteraceae)

Abstract

Studies about reproductive biology of weed species can have implications on the establishment of controlling practices that minimize the effects of these weed populations on agricultural fields. The pollination biology of Bidens alba (L.) DC., B. pilosa L., and Bidens subalternans DC., was studied at different sites and climatic seasons. Bidens pilosa and B. subalternans are widely distributed in agricultural areas, in disturbed habitats, and along road sides. Bidens alba occur only along the coast. The three species are self-compatible and non agamospermous. The composition of the pollinator community changes during the year and between sites. Hymenopterans and lepidopterans are the most frequent visitors to Bidens species in both areas studied. Although the species are self-compatible, the presence of pollinators may affect the levels of inbreeding. The attraction of insects by Bidens species may be benefical to agricultural crop and may also have important implications for conservation biology.

Floral biology of Senecio macrophyllus M. BIEB. (Asteraceae), a rare Central European steppe plant

“…The growth of ligulate flowers in S. macrophyllus begins early in the morning (6.00-8.00), before the gradual progress of disc florets, which was observed fundamentally from 10.00 h with peaks between 15.00 and 18.00. According to many authors, a major function of ligulate flowers is visual attraction of pollinators [7,10,46]. Another visual attractant for insect visitors to S. macrophyllus is the changeable color of anthers in disc florets, which acts as an indicator of flower reward availability.…”

“…We observed a particularly diverse composition of lepidopterans, with their participation reaching 13.9% of all visitors. Butterflies are considered as important foragers of Asteraceae [3,10], although this group of insect visitors was not recorded by Knuth [52], who apart from Apis mellifera observed only Coleoptera, Diptera, and Hymenoptera foraging on S. macrophyllus. Some authors suggest that the foraging behavior of butterflies maintains the gene flow between populations, as they move over longer distances than other flower visitors do [27,37].…”

“…An adequate amount of functional pollen that may accomplish its successful delivery to the ovule to complete fertilization is necessary for seed and fruit set [60]. Both the pollen limitation and disorders in pollen biology may have a significant impact on the potential seed set [10,46,56,61] and hence the population structure and population stability.…”

“…[8]. To assure the exchange of pollen between different individuals, Asteraceae plants are generalists with flowers adapted to pollination by several insect groups -Hymenoptera, Coleoptera, Diptera, and Lepidoptera [7,[9][10][11].…”

Temperatura base, plastocrono e número final de nós no malmequer-do-campo

“…No entanto, são escassos os trabalhos relacionados à biologia de A. montevidensis, os quais podem fornecer informações para definir os tratos culturais e o manejo da espécie com vistas ao seu cultivo (GRAMBONE-GUARATINI et al, 2004).…”