Visitantes florais de plantas invasoras de áreas com fruteiras irrigadas Floral visitors of weed plants of irrigated orchard areas

As plantas invasoras afetam a produtividade das fruteiras irrigadas, sendo necessários estudos sobre sua ecologia, principalmente formas de reprodução e associação com insetos. O presente trabalho foi desenvolvido em Petrolina-PE, objetivando classificar os visitantes florais de plantas invasoras em polinizadores e pilhadores, de acordo com o comportamento apresentado. As observações foram feitas de maio a outubro de 1998, em 26 dias não consecutivos, no intervalo das 7h00 às 16h00. As invasoras foram classificadas em nectaríferas e poliníferas, quando visitadas para retirada exclusiva de néctar ou de pólen; e em mistas, quando visitadas para retirada dos dois recursos. Para a análise de freqüência foi adotado um sistema de notas: a- número de visitas >30, b- entre 10 e 30 e c- <10 visitas. Das 24 invasoras observadas, 14 foram consideradas nectaríferas, seis poliníferas e quatro mistas. Entre os visitantes florais foram registradas abelhas (Xylocopa grisescens, X. frontalis, Centris aff. perforator, Ptilotrix aff. plumata, Diadasina riparia, Apis mellifera, Trigona spinipes, Eulaema nigrita), borboletas (Ascia monuste, Papilio thoas brasiliensis, Agraulis vanillae) e beija-flores (Phaethornis sp., Chlorostilbon aureoventris). As abelhas apresentaram maior número de espécies (61,5%) e de visitas, além de agirem como polinizadores em 83% das invasoras visitadas. As borboletas foram consideradas pilhadores de néctar, participando como polinizadores de Emilia spp. e os beija-flores, considerados polinizadores das invasoras visitadas.<br>Weeds can impair yield of irrigated fruit crops, studies about their ecology being needed, especially ways of reproduction and association with insects. This work was carried out in Petrolina, PE, Brazil with the objective of identifying the floral visitors of weeds, and classifying them as pollinators and pollen and/or nectar thieves, according to their behavior. The observations were made between May and October of 1998, in 26 not consecutive days, between 7:00 am and 4:00 pm. The weeds were classified in nectariferous and polliniferous when these were visited exclusively for collection of nectar or pollen, and mixed when these were visited to collect both. A grade system was adopted for the frequency evaluation: a- number of visits >30, b - between 10 to 30, c - <10. Among the 24 weeds observed, 14 were classified as nectariferous, six as polliniferous and four were considered mixed. Among the floral visitors, the following bees were registered (Xylocopa grisescens, X. frontalis, Centris aff. perforator, Ptilotrix aff. plumata, Diadasina riparia, Apis mellifera, Trigona spinipes, Eulaema nigrita), butterflies (Ascia monuste, Papilio thoas brasiliensis, Agraulis vanillae) and hummingbirds (Phaethornis sp., Chlorostilbon aureoventris). The bees were predominant in number of species (61.5%) as well as in the frequency of visits. They acted as pollinator agents in 83% of weeds visited. The butterflies were considered nectar thieves, and they acted as pollinator agents only in the case of the species of Emilia. The hummingbirds acted as pollinators for all visited species.