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% 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% 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.

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Entomofauna visitante de Stenolobium stans (Juss.) Seem (Bignoniaceae), durante seu período de floração

The floral biology of three weeds, Ipomoea cairica, I. grandifolia and I. nil (Convolvulaceae), was studied in Botucatu and Jaboticabal, Sao Paulo, in southeastern Brazil. The three species are melittophilous, with a varied set of floral visitors, but with some overlapping. Cluster analysis using Jacquard similarity index indicated a greater similarity among different plant species in the same locality than among the populations at different places, in relation to floral visitor sets. The promiscuous and opportunistic features of the flowers were shown, with such type of adaptation to pollination being advantageous to weeds since pollinator availability is unpredictable at ruderal environments.

/pdf/floral-biology-and-breeding-system-of-three-ipomoea-weeds-273ojzj0a3.pdf

Floral biology and breeding system of three Ipomoea weeds

The present work was carried out during March/1995 to July/1997, to study aspects of the phenology, pollination and reproduction of Ipomoea asarifolia growing at Fazenda Catalunha, Santa Maria da Boa Vista, PE. I. asarifolia is a perennial creeping liana with floration registered in the period of March to October, characterized as a cornucopian pattern of flowering. The flowers are gathered in cymes, with a pink funnel-like corolla with magenta mesopetals working as nectar guides. The anthesis is diurnal (05:30 - 06:00 h) and the flowers lasting for approximately six hours. The amount of nectar secreted by flower is less then 1µl. Bees Megachilidae and Apidae were the main visitors of this Convolvulaceae. Liturge huberi Ducke was considered as effective pollinatior, and Acamptopoeum prinii Holm. and Diadasina riparia Ducke as occasional. Ipomoea asarifolia is self-incompatible, producing fruits and viable seeds only after crossed pollination. However the tests of pollen tube growth showed that 10 hours after pollination, pollen tubes reached the micropile of both self- and cross-pollinated ovules, suggesting a late acting self-incompatibility system. The germination tests showed that only the seeds obtained in natural conditions (93,3%) and from cross-pollination experiment (100%) were viable, reinforcing the data obtained in the reproduction system.

http://www.scielo.br/pdf/abb/v17n3/17704.pdf

Ecologia da polinização de Ipomoea asarifolia (Ders.) Roem & Schult. (Convolvulaceae) na região semi-árida de Pernambuco.

During the rainy season many species of Convolvulaceae bloom simultaneously in the Caatinga of northeast Brazil. In a Caatinga nature reserve we studied pollination and breeding systems of three sympatric species of Convolvulaceae, Ipomoea bahiensis, I. nil, and Merremia aegyptia, focusing on pollen partitioning among flower visitors and pollen flow. The study showed that only oligolectic bees collected pollen and that these species had different preferences among the three species of Convolvulaceae: pollen of Ipomoea bahiensis, the only self-incompatible species, was collected mainly by Melitoma segmentaria, M. osmioides, and Melitomella murihirta; pollen of I. nil by Lithurgus huberi; and that of Merremia aegyptia by Ancyloscelis apiformis and an undescribed species of this genus. Introduced honey bees visited only flowers of Merremia aegyptia, where they were extraordinarily frequent flower visitors. However, they discarded the pollen grains, which led to almost 50% pollen loss. No polylectic bee species compete for pollen with the oligolectic species. Partitioning of pollen diminishes competition for floral resources in this specialized plant–pollinator association.

Pollen partitioning of three species of Convolvulaceae among oligolectic bees in the Caatinga of Brazil

Apresentamos os primeiros registros sobre a biologia da polinizacao de Jacquemontia montana (Moric.) Meisn. (Convolvulaceae), uma trepadeira com ampla distribuicao na Chapada Diamantina, Bahia. Os objetivos deste estudo foram: (1) caracterizar a morfologia e biologia floral; (2) amostrar os visitantes; e (3) inferir os possiveis polinizadores, baseando-se no comportamento de forrageio. Observacoes e amostragens foram conduzidas em duas manchas das 8:00 as 15:30 horas, nos dias 15 e 16 de maio de 2007. A corola e amarela, tem forma de disco, pentâmera, gamopetala, actinomorfa. A corola exposta tem largura media de 22,43 ± 1,81 mm. A receptividade estigmatica ocorre das 8:00 as 15:30 horas e a viabilidade polinica das 9:00 as 15:30 horas, se sobrepondo fortemente. O polen, porem, apresentou forte declinio em numero, devido a retirada pelos visitantes, mas nao em viabilidade durante a antese. Insetos nectarivoros (Coleoptera, Diptera, Hymenoptera) e herbivoros (Orthoptera) visitaram as flores. Hymenoptera incluiu representantes das familias Formicidae (formigas) e Halictidae (Dialictus spp.). Machos e femeas de Dialictus spp. foram os visitantes mais frequentes. O comportamento e duracao das visitas dessas abelhas variaram conforme o recurso coletado (i.e., polen ou nectar). As especies de Dialictus foram os polinizadores potenciais de J. montana, considerando sua frequencia, contato com orgaos reprodutivos, e pelo fato de carregar apenas polen de J. montana na superficie ventral do torax, abdome e pernas. Embora nao tenha sido quantificado, o nectar deve estar disponivel ate o final da tarde, considerando o comportamento das abelhas nas flores nesse periodo. A relacao polen:ovulo, no valor de 1.200:4, sugere a ocorrencia de xenogamia facultativa.

/pdf/records-on-floral-biology-and-visitors-of-jacquemontia-3h7v12lbkw.pdf

A Amaral Junior

Papers

Polinização em Ipomoea cairica (L.) Sweet. (Convolvulaceae)