Utilização dos recursos florais pelos visitantes em Sparattosperma leucanthum (Vell.) K. Schum. (Bignoniaceae)

Abstract

-Aiming to estimate the rate of exploitation of the fl oral resources of Sparattosperma leucanthum (Vell.) K. Schum. as well as the interaction with their fl oral visitors in the pollination, the number of visits by fl ower was sampled, according to the type of visitation, the collected resource and the visitor's behavior during the forage for fl owers. The fl oral visitors were grouped into seven guilds, organized in decreasing order of benefi t to the S. leucanthum fl ower's pollination: effective pollinator, occasional pollinator, endogamic pollinator, generalist visitor, thievery visitor, thievery-pillager ant and pillager visitor. The total of 48.2 ± 8.84 visits were recorded by fl ower. Nearly 50% of the visits resulted in nectar thief or pillage, which posed some problems to the reproduction of S. leucanthum, such as the drop in the attractiveness to pollinators and the harm to the fl ower's reproductive tissues. Trigona spinipes (Fabr.) (Hymenoptera: Apidae) was considered the most harmful species owing to the high frequency of pillage and forage. Bombus sp1, however, was probably the species that pollinated S. lecanthum fl owers the most, making use of the crossed pollination.KEY WORDS: Foraging behavior, foraging frequency, pollinator, nectar thief-pillage RESUMO -Com o objetivo de estimar a taxa de exploração dos recursos fl orais de Sparattosperma leucanthum (Vell.) K. Schum. e a interação com seus visitantes fl orais na polinização, foram amostradas as visitas realizadas por fl or, agrupadas segundo o tipo de visitação e o recurso coletado, registrando-se o comportamento do visitante durante o forrageamento às fl ores. Os visitantes fl orais foram agrupados em sete guildas, em ordem decrescente de benefício à polinização das fl ores de S. leucanthum: polinizador efetivo, polinizador casual, polinizador endogâmico, visitante generalista, visitante furtador, formiga furtadora-pilhadora e visitante pilhador. Foram constatadas 48,2 ± 8,84 visitas por fl or, sendo que a guilda polinizador efetivo respondeu por 16,1 ± 8,43 (33,3%) visitas por fl or. Quase 50% das visitas resultaram no furto ou pilhagem de néctar, representando prejuízos à reprodução de S. leucanthum, como a redução da atratividade aos polinizadores e o dano aos tecidos reprodutivos da fl or. Trigona spinipes (Fabr.) (Hymenoptera: Apidae) foi considerada a espécie mais prejudicial devido à alta freqüência de pilhagem e de forrageamento, enquanto Bombus sp1 foi provavelmente a espécie que mais polinizou fl ores de S. leucanthum através da polinização cruzada. PALAVRAS-CHAVE: Forrageamento, freqüência, polinizador, furto-pilhagem de néctarSparattosperma leucanthum (Vell.) K. Schum. é uma planta nativa do Brasil, típica da Mata Atlântica e da fl oresta semidecídua da Bacia do Paraná, sendo que apenas no Mato Grosso do Sul tornou-se uma séria infestante de pastagens implantadas em área de antigas fl orestas (Lorenzi 2000a). Apresenta rápido crescimento, podendo ser empregada em plantios mistos para restauração da vegetação em áreas de...

Exploitation of floral resources on Sparattosperma leucanthum (Bignoniaceae): foraging activity of the pollinators and the nectar and pollen thieves

“…As for the hummingbirds, the specimens observed at the flowers were photographed and later identified in the Biology Department at the Federal University of Mato Grosso do Sul. The strategy to ascertain the activity of floral visitors by visual observation, adopted in this study, presents both positive and negative bias, as reported by Polatto and Alves Jr. (2008) and Cane (2001), respectively. Another reason for not using the method of sweeping flowers with an entomological net (Sakagami et al 1967), adopted in most studies, is the decrease in the foraging rate throughout the day, as flowers are damaged (or even drop off) because of the use of the insect collecting instrument.…”

“…These visitors were classified as: (1) thieves: the animals which obtain floral resources by entering the corolla opening without damaging the flowers but that may pollinate them accidentally in case of contact between the stigma of the flower and parts of the body impregnated with pollen grains; (2) primary robbers-those which puncture the external face of the corolla near the nectary to reach nectar; or (3) secondary robbers-those which use the holes previously made by primary robbers (Inouye 1980;Polatto and Alves Jr. 2008).…”

“…Many researches were done on the collecting activity of bees in Bignoniaceae species of the Neotropical Region, including in Atlantic Forest and Cerrado biomes (e.g., Yanagizawa and Maimoni-Rodella 2007;Silva et al 2007;Polatto et al 2007;Guimarães et al 2008;Polatto and Alves Jr. 2008;Milet-Pinheiro and Schlindwein 2009;Almeida-Soares et al 2010;Curti and Ortega-Baes 2011). Nevertheless, little is known about the foraging activity of the floral visitors in Brazilian environments which are in stage of regeneration.…”

Pollination of Adenocalymma bracteatum (Bignoniaceae): floral biology and visitors

“…The second hypothesis is that the pillage has potential negative effects on plant reproduction, what seems to be more applicable to our study. The negative effects of pillage have been shown in previous research due to the damage to the reproductive tissues (Traveset et al 1998, Polatto & Alves Jr 2008, the lower attractiveness of pillaged fl owers to effi cient pollinators (Roubik 1982, Irwin & Brody 1998, Traveset et al 1998, Cotton 2001, the resource investment to replace the removed nectar (Pyke 1991, Navarro 1999, and also the aggressive interference of pillagers on pollinators (Roubik 1982).…”

“…Since these were legitimate visits, these bees can be considered as effective pollinators. Another trait favouring effi cient pollination by many large pollinators is their potential mobility among plants (Polatto & Alves Jr 2008).…”