Biomedical subjects

M Gimenes

Publications and source records attributed to M Gimenes.

3 recordsLinked to original sources

PubMed2004

Interaction between visiting bees (Hymenoptera, Apoidea) and flowers of Ludwigia elegans (Camb.) hara (Onagraceae) during the year in two different areas in São Paulo, Brazil.

This study was designed to characterize the interactions between Ludwigia elegans flowers and visiting bees during two years in two areas 200 km apart, at the same latitude (approximately 22 masculine 48'S) but at different altitudes (Alumínio, 600 m, and Campos do Jordão, 1500 m), in the State of São Paulo, Brazil. As these flowers open simultaneously in the morning and lose their petals by sunset, interaction with bees occurs only during the photophase. Flowers of L. elegans were mainly visited by bees, the most frequent species being: Tetraglossula anthracina (Michener, 1989) (Colletidae), Rhophitulus sp. (Andrenidae), and Pseudagapostemon spp. (Halictidae), all considered specialized bees for collecting pollen and nectar from these flowers, as well as the generalist bee Apis mellifera Linnaeus, 1758 (Apidae). The specialist bees were temporally adjusted to the opening schedule of the flower, which occurs primarily in the morning, but shows a circannual variation. T. anthracina appears in both study areas, but only between December and April. The annual activity patterns of these specialist bees are synchronized to the phenology of L. elegans. Photoperiod and temperature cycles are suggested as the main synchronizers of both bees and plants.

Altitude↗

PubMed1996

Control of environmental variables in a field study using a chronobiological protocol.

Field work in chronobiology usually is based on observations which differ from those in laboratory studies which are experimental. Non-invasive protocols are recommended in the field in order not to introduce additional variables. We propose an alternative strategy here. The effect of environmental cycles on biological rhythms can be estimated when the observations are made in more than one area. The areas under study must have at least one characteristic in common which is a guarantee that the limits of oscillation of an environmental cycle will be similar. This proposal has been tested using the biological system consisting of an Onagraceae plant, Ludwigia elegans, and its bee visitors, which is found in two localities at the same latitude, but at different altitudes. Under the same photoperiod, but with the mean temperature ranging within known limits, it was possible to determine temporal characteristics of the system in the field by examining the effects of the light/dark and temperature daily cycles.

Animals↗

PubMed1993

Chronobiologic aspects of a coadaptive process: the interaction of Ludwigia elegans flowers and their more frequent bee visitors.

Field observations spanning 1 year of the visits of two bee species--Tetraglossula bigamica (Hymenoptera: Colletidae) and Pseudagapostemon brasiliensis (Hymenoptera: Halictidae)--to the flowers of Ludwigia elegans (Onagraceae) evinced the existence of circadian and circannual components in the rhythms of activity both of plant and bees. In addition to morphological adaptations to the flower, the bees were temporally adjusted to each other and to the flower's opening and closing mechanisms. At the observation locality (Ribeirão Preto, São Paulo, Brazil--latitude 21 degrees-21 degrees 30S), the plant bloomed year-round. The flowers of the same population open simultaneously at the onset of the photophase, pollen and nectar being available almost immediately. Withering occurs in the afternoon of the same day. Although many bee species visited the flowers, T. bigamica and P. brasiliensis were the most frequent visitors, but their yearly rhythms were phased opposite to one another. Circadian rhythms were detected in pollen and nectar harvest. Comparisons of acrophases showed significant differences for males' and females' nectar collecting rhythm and for females' pollen harvest rhythm. As for the circannual component, acrophases of all rhythms occur at progressively later times from December to July when the migration is reversed until November. These data strongly suggest that the relationship between L. elegans and T. bigamica and P. brasiliensis is in accordance with a clearly temporal pattern and that the two bee species are temporally separated in nature.

Adaptation, Physiological↗