Floral biology of Tropaeolum majus L. (Tropaeolaceae) and its relation with Astylus variegatus activity (Germar 1824) (Coleoptera: Melyridae)

Abstract

Tropaeolum majus L. (nasturtium) is a culture popularly known by its medicinal, ornamental and culinary utility. This work aimed to evaluate the interaction between Astylus variegatus (Germar 1824) (Coleoptera: Melyridae) and the nasturtium flowers associated to the weeks of flourishing, in order to conceive the floral mechanims used by the species to attract A. variegatus. The insects collection was achieved with an entomologic net by the sweeping method, during the weekly flowering, at two hours, from 7am to 5pm. The studies of floral biology were carried out in twenty flowers by the analysis of measures and the arrangement of the floral parts. The nasturtium flower offers pollen and nectar to the insect as a compensation. However, it was observed that A. variegatus only collects pollen as a nutritious resource. Tropaeolum majus presents several flowers for each individual and, during the visits, A. variegatus walked throughout the interior of the flower, among the stamens and contacting the ventral region of its body, and while passing through the stigma it lodged the pollen. Sometimes, it uses the internal cavity for sheltering and mating. The visits occurred preferably on the second and fifth weeks of flourishing, with a populational fluctuation between 9am and 11am.<br>Tropaeolum majus L. (capuchinha) é uma cultura muito conhecida pelo seu valor medicinal, ornamental e culinário. O objetivo do trabalho foi avaliar a interação entre Astylus variegatus (Germar 1824) (Melyridae) com as flores de capuchinha, associado às semanas de florescimento, visando entender os mecanismos florais utilizados pela espécie na atração de A. variegatus. A coleta dos insetos foi realizada com rede entomológica pelo método varredura durante a floração, semanalmente, a cada duas horas, no período de 7 às 17 horas. Os estudos da biologia floral foram realizados em vinte flores, analisando as medidas e disposição das peças florais. A flor de capuchinha oferece ao inseto pólen e néctar como recompensa, contudo, foi observado que A. variegatus coleta apenas pólen como recurso alimentar. Tropaeolum majus apresenta várias flores por indivíduo sendo que durante as visitas A. variegatus caminhava por todo o interior da flor, entre os estames contatando a região ventral de seu corpo e, ao passarem pelo estigma, depositava o pólen. Em alguns momentos, utiliza a cavidade interna para abrigo e acasalamento. As visitas ocorreram preferencialmente na segunda e quinta semanas de florescimento com pico populacional entre as 9 e 11:00h

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oai:doaj.org/article:53c875c1462a4a03857189e1df2e5f6cLast time updated on 12/18/2014

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