A estrutura da guilda de abelhas e vespas visitantes florais de Waltheria americana L. (Sterculiaceae)

Abstract

Dedicamos este trabalho à memória do saudoso amigo Hermógenes de Freitas Leitão Filho pela sua expressiva contribuição ao conhecimento botânico e ecológico de plantas invasoras. ABSTRACT -The number of flowers produced by the weed Waltheria americana L (Sterculiaceae) and the number of flowering dicot species were quantified in two sites at the Campus of the Universidade Federal de Minas Gerais, to evaluate their seasonal relative importance as a source of nectar and pollen to a guild of 72 species of wasps and 37 species of bees. Differences between the average number of flowering dicot species between the dry and rainy seasons were found in only one of the sites. A significant difference in the number of flowers produced by W. americana between the two seasons was found in only one of the sites. Only the number of wasps visiting W. americana varied between seasons. Seasonal variation in guild composition was observed in one of the sites and only the bees showed a strong variation in species composition along the year. There was a positive correlation between the number of flowering dicot species and both the number of bee visits, and the number of flowers of W. americana. However, there were no differences between seasons in the average of visits. On the other hand, there was no correlation between the number of wasp visits to W. americana and either the number of flowers of W. americana or the number of other flowering dicot species in one site. On average, wasps visit W. americana more frequently in the rainy season than in the dry one in one of the sites, but the inverse occurred in the other site. The daily flower visitation of wasps and bees was most intense, and similar, between nine and 13 h. Because W. americana flowers year round and is a source of nectar for bees and wasps, its management could be important to maintain the diversity of bees and wasps in disturbed areas or agroecosystems, thus supporting insects which may act as pollinators and biological control agents, respectively.

Diversidade de abelhas (Hymenoptera: Apoidea) em inflorescências de Piper hispidinervum (C.DC.)

“…A preferência das abelhas pelos primeiros horários da manhã (6h às 8h) foi observada por Gonçalves et al (1996) e Viana (1999. Outros autores também relataram a ocorrência de maior abundância em diferentes plantas, durante o período da manhã, porém em maior amplitude de horários (Albuquerque & Rêgo 1989, Macedo & Martins 1999, Manente-Balestieri & Machado 1999.…”

“…Segundo Heinrich (1993) citado por Viana (1999) as abelhas que vivem em locais com temperaturas diurnas elevadas regulam os seus períodos de atividade externa, para evitar o estresse provocado pelo aquecimento do corpo, concentrando sua visitação nas primeiras horas da manhã (Macedo & Martins 1999). As elevadas temperaturas diurnas da região de Rio Branco podem ser responsáveis pela concentração, no início da manhã, das atividades das diferentes espécies de abelhas.…”

The flowering-visiting bees at the ecological station of the Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil

“…High variations in fauna composition is believed to be common among different sites within an area (Heithaus 1979, Cure 1983. Besides, areas in early successional stages have a great variability in important habitat components for bees else within narrow habitat areas, such as pollen and nectar sources available in weeds flowers and sites for nesting (Saure 1996;Macedo & Martins 1998, 1999. The highest bee richness found at trails of disturbed areas can be probably due to the highest diversity of weeds occurring in this area.…”

Onde os mais Adaptados Permanecem: Comunidade de Abelhas sem Ferrão (Hymenoptera: Apidae, Meliponini) em Áreas Urbanas do Município de Ubá, Minas Gerais, Brasil

“…As amostragens foram realizadas entre março de 2011 e janeiro de 2012, duas vezes por semana, entre os horários de 09:00 até as 16:00, período de maior atividade das abelhas, o que facilita a localização dos seus ninhos (MaCedo & Martins 1999). Dentro das SU's foram realizadas buscas ativas dos ninhos, vistoriando muros, edificações, calçadas e áreas jardinadas, locais considerados comuns para nidificação destes insetos (noGueira-neto 1997).…”