Cor floral influencia visita??o de abelhas coletoras de ?leo em Byrsonima variabilis A. Juss (Malpighiaceae).

Programa de P?s-Gradua??o em Ecologia de Biomas Tropicais. Departamento de Biodiversidade, Evolu??o e Meio Ambiente, Instituto de Ci?ncias Exatas e Biol?gicas, Universidade Federal de Ouro Preto.Diversos atributos florais podem indicar a presen?a de recursos aos polinizadores e cor ? um deles. Embora 78 fam?lias de angiospermas apresentem mudan?a de cor floral, a maior parte dos estudos se restringe a entender como essa altera??o influencia o comportamento de forrageio de oper?rias de insetos sociais em busca de um s? recurso: o n?ctar. Byrsonima variabilis (Malpighiacea) ? uma planta que possui ?leo e p?len como recursos florais. ?leos florais atraem abelhas coletoras de ?leo que os utilizam na impermeabiliza??o dos ninhos e aprovisionamento larval. Neste estudo, caracterizamos os padr?es de reflet?ncia espectral de flores de B. variabilis ao longo da antese e avaliamos se a mudan?a de cor ? induzida pela poliniza??o. Em seguida, verificamos como esses padr?es de cor s?o percebidos pelas abelhas e se influenciam seu comportamento de coleta. Flores de B. variabilis foram visitadas por abelhas coletoras de ?leo da tribo Centridini e da tribo Tapinotaspidini. F?meas do primeiro grupo s?o as ?nicas que apresentam tamanho e comportamento de manuseio floral adequados ? poliniza??o. Abelhas dos dois grupos visitaram preferencialmente flores com p?talas estandartes amarelas quando buscavam por p?len, mas coletaram indiscriminadamente em flores com diferentes cores de p?tala estandarte quando buscavam por ?leo floral. Em um experimento em que removeu-se anteras de flores frescas, as abelhas coletaram quase que exclusivamente em flores com anteras, demonstrando que n?o apenas a cor da flor, mas a presen?a do recurso em si tamb?m influenciou nas decis?es de visita pelos polinizadores. Os resultados apresentados neste estudo mostraram que abelhas coletoras de ?leo reconhecem cores florais durante seu forrageio na busca de p?len, e que a cor das anteras e a presen?a de p?len tamb?m s?o empregados como sinal e influenciam na decis?o de visitar ou n?o a flor.Several floral attributes may indicate the presence or absence of resources to pollinators, and color is one of them. Although 78 families of angiosperms exhibit floral color change, most studies are restricted to understanding how this change could influence the foraging behavior of social insect workers searching for a single resource, nectar. Byrsonima variabilis (Malpighiacea) is a plant that has oil and pollen as floral resources. Floral oils attract oil collecting bees that use them for waterproofing nests and larval supply. Studies on color preference usually associate it with the presence of the nectar resource. In this study, we characterize the spectral reflectance patterns of B. variabilis flowers throughout the anthesis and evaluate whether the color change is induced by pollination. Hereafter, we verify how these color patterns are perceived by bees and influence their collect behavior. Flowers of B. variabilis were visited by big Centridini and small Tapinotaspidini oil collecting bees. Females of the first group are the only with adequate size and floral handling behavior which leads them touch stigma when collecting. Bees of the two groups visited yellow flowers preferentially when collecting pollen and collected indiscriminately on flowers of different colors when searching for floral oil, In an experiment in which anthers were removed from fresh flowers, the bees collected almost exclusively on flowers with anthers, demonstrating that not only flower color, but the presence of the resource itself also influenced the visitation decisions. The results presented in this study showed that oil collecting bees recognize floral colors during their foraging in the search for pollen, and the color of anthers and pollen is used as signal to bees decide to visit this flowers or not

Floral colour change in Byrsonima variabilis (Malpighiaceae) as a visual cue for pollen but not oil foraging by oil-collecting bees.

Pollinators search for multiple flora resources throughout their life cycle. Most studies, however, only assess how bees discriminate floral cues in the context of nectar foraging. In the present study, we sought to elucidate whether oil-collecting bees discriminate flowers of Byrsonima variabilis (Malpighiaceae) with petals of different colours when foraging for pollen or oil. As the colour of the standard petal changes during anthesis, we characterised the spectral reflectance patterns of flowers throughout anthesis and modelled chromatic perceptual space to determine how these colour patterns are perceived by bees. Through the quantification of flower pollen in the different phases, we found that the colour of the standard petal is an honest cue of the presence of pollen. Centridine bees preferentially visited flowers with a yellow (bee’s green) colour when searching for pollen, but indiscriminately visited flowers with different petal colours when searching for floral oil. We suggest that standard petals, in the species studied and others of the genus, like nectar guides, act as pollen guides, which oil-collecting females use to detect pollen-rich flowers. Moreover, they use different floral clues during foraging for different resources in the same host plant

Floral colour change in Byrsonima variabilis (Malpighiaceae) as a visual cue for pollen but not oil foraging by oil-collecting bees

Pollinators search for multiple flora resources throughout their life cycle. Most studies, however, only assess how bees discriminate floral cues in the context of nectar foraging. In the present study, we sought to elucidate whether oil-collecting bees discriminate flowers of Byrsonima variabilis (Malpighiaceae) with petals of different colours when foraging for pollen or oil. As the colour of the standard petal changes during anthesis, we characterised the spectral reflectance patterns of flowers throughout anthesis and modelled chromatic perceptual space to determine how these colour patterns are perceived by bees. Through the quantification of flower pollen in the different phases, we found that the colour of the standard petal is an honest cue of the presence of pollen. Centridine bees preferentially visited flowers with a yellow (bee’s green) colour when searching for pollen, but indiscriminately visited flowers with different petal colours when searching for floral oil. We suggest that standard petals, in the species studied and others of the genus, like nectar guides, act as pollen guides, which oil-collecting females use to detect pollen-rich flowers. Moreover, they use different floral clues during foraging for different resources in the same host plant