Antagonistas versus mutualistas: como as interações entre uma espécie especializada com seus florívoros e polinizadores são mediadas por voláteis florais
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Data
2021-07-30
Autores
Oliveira, Pablo Henrique de
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Universidade Estadual Paulista (Unesp)
Resumo
Esfingofilia é a denominação das plantas adaptadas à polinização por mariposas da família Sphingidae, cuja atração se dá em grande parte por meio de compostos orgânicos voláteis (COVs). Mandevilla longiflora é uma espécie cuja morfologia floral sugere polinização exclusiva por espécies de esfingídeos com probóscide longa, embora esfingídeos nunca tenham sido observados nas populações de M. longiflora do Brasil, e a espécie seja frequentemente visitada por besouros Cyclocephalini (Melolonthidae), cuja atração em outras espécies se dá através de COVs florais. Dada a grande frequência de uma espécie do gênero Cyclocephala nas flores de M. longiflora, esse trabalho teve como objetivos analisar o papel de COVs na atração dos potenciais polinizadores primários de M. longiflora, i.e., mariposas da família Sphingidae, bem como do seu principal visitante floral, i.e., besouros Cyclocephalini. Nós testamos se estes besouros poderiam atuar como polinizadores de M. longiflora. Além disso, realizamos observações dos visitantes florais e experimentos de exclusão de visitantes para analisar a contribuição dos besouros para reprodução da espécie. Também estudamos a biologia floral, e por meio de experimentos de polinização controlada, analisamos seu sistema reprodutivo e a dependência de polinizadores para a reprodução. Finalmente, coletamos e analisamos os COVs produzidos pelas flores de M. longiflora e testamos a atratividade desses COVs aos besouros. M. longiflora é uma espécie autocompatível, porém estritamente dependente de polinizadores para a sua reprodução. Foram registradas apenas cinco visitas de esfingídeos de uma única espécie, Agrius cingulata, o que sugere que estas mariposas são visitantes pouco frequentes, mas atuam como polinizadores bastante efetivos da espécie. O principal COV produzido pela flor foi o 3-metil-butiraldoxima, o qual foi altamente atrativo a Cyclocephala paraguayensis, o principal visitante floral e florívoro de M. longiflora. Os experimentos de exclusão mostraram que o besouro não atua como polinizador de M. longiflora, agindo apenas como herbívoro floral, consumindo principalmente as anteras e o pólen da flor. Apesar da existência de diversas espécies atraentes aos besouros Cyclocephalini na área de estudo, C. paraguayensis foi registrado apenas em M. longiflora, tendo o comportamento de um florívoro de uma flor esfingófila e sendo altamente atraído pelos voláteis florais da espécie. A dependência estrita de polinizadores para a sua reprodução, associada à baixa frequência de esfingídeos levou a uma elevada limitação de pólen na população estudada. Considerando o comportamento desses visitantes florais, este trabalho mostra que as interações planta-esfingídeo e planta-besouro são mediadas pelos mesmos voláteis florais resultando em um importante trade-off entre a atração dos polinizadores e dos principais florívoros. Embora essa interação possa ser prejudicial para o fitness da planta, a ocorrência de autocompatibilidade permite que as visitas de esfingídeos, ainda que pouco frequentes, sejam extremamente eficientes.
Sphingophilia is the name for plants adapted to pollination by moths of the Sphingidae family, whose attraction is largely through volatile organic compounds (VOCs). Mandevilla longiflora is a species whose floral morphology suggests exclusive pollination by species of sphingids with long proboscis, although sphingids have never been observed in populations of M. longiflora in Brazil, and the species is frequently visited by Cyclocephalini beetles (Melolonthidae), whose attraction in other species occur through floral VOCs. Given the high frequency of a species of the genus Cyclocephala in the flowers of M. longiflora, this work aimed to analyze the role of VOCs in attracting potential primary pollinators of M. longiflora, i.e., moths of the family Sphingidae, as well as its main floral visitor, i.e., Cyclocephalini beetles. We tested whether these beetles could act as pollinators for M. longiflora. In addition, we conducted floral visitor observations and visitor exclusion experiments to analyze the contribution of beetles to species’ reproduction. We also study floral biology, and through controlled pollination experiments, we analyze their reproductive system and their dependence on pollinators for reproduction. Finally, we collected and analyzed the VOCs produced by M. longiflora flowers and tested the attractiveness of these VOCs to beetles. M. longiflora is a self-compatible species, but strictly dependent on pollinators for its reproduction. Only five visits were recorded by sphingids of a single species, Agrius cingulata, which suggests that these moths are infrequent visitors, but act as very effective pollinators of the species. The main VOC produced by the flower was 3-methyl-butyraldoxime, which was highly attractive to Cyclocephala paraguayensis, the main floral visitor and florivorous of M. longiflora. The exclusion experiments showed that the beetle does not act as pollinator for M. longiflora, acting only as a floral herbivore, consuming mainly the anthers and pollen of the flower. Despite the existence of several species attractive to Cyclocephalini beetles in the study area, C. paraguayensis was recorded only in M. longiflora, having the behavior of a florivore of a sphingophilous flower and being highly attracted by the volatile floral of the species. The strict dependence on pollinators for their reproduction, associated with the low frequency of sphingids, it led to a high pollen limitation in the studied population. Considering the behavior of these floral visitors, this work shows that the plant-sphingid and plant-beetle interactions are mediated by the same floral volatiles, resulting in an important trade-off between the attraction of pollinators and the main florivores. Although this interaction can be detrimental to the plant's fitness, the occurrence of self-compatibility allows sphingids’ visits, even if infrequent, to be extremely efficient.
Sphingophilia is the name for plants adapted to pollination by moths of the Sphingidae family, whose attraction is largely through volatile organic compounds (VOCs). Mandevilla longiflora is a species whose floral morphology suggests exclusive pollination by species of sphingids with long proboscis, although sphingids have never been observed in populations of M. longiflora in Brazil, and the species is frequently visited by Cyclocephalini beetles (Melolonthidae), whose attraction in other species occur through floral VOCs. Given the high frequency of a species of the genus Cyclocephala in the flowers of M. longiflora, this work aimed to analyze the role of VOCs in attracting potential primary pollinators of M. longiflora, i.e., moths of the family Sphingidae, as well as its main floral visitor, i.e., Cyclocephalini beetles. We tested whether these beetles could act as pollinators for M. longiflora. In addition, we conducted floral visitor observations and visitor exclusion experiments to analyze the contribution of beetles to species’ reproduction. We also study floral biology, and through controlled pollination experiments, we analyze their reproductive system and their dependence on pollinators for reproduction. Finally, we collected and analyzed the VOCs produced by M. longiflora flowers and tested the attractiveness of these VOCs to beetles. M. longiflora is a self-compatible species, but strictly dependent on pollinators for its reproduction. Only five visits were recorded by sphingids of a single species, Agrius cingulata, which suggests that these moths are infrequent visitors, but act as very effective pollinators of the species. The main VOC produced by the flower was 3-methyl-butyraldoxime, which was highly attractive to Cyclocephala paraguayensis, the main floral visitor and florivorous of M. longiflora. The exclusion experiments showed that the beetle does not act as pollinator for M. longiflora, acting only as a floral herbivore, consuming mainly the anthers and pollen of the flower. Despite the existence of several species attractive to Cyclocephalini beetles in the study area, C. paraguayensis was recorded only in M. longiflora, having the behavior of a florivore of a sphingophilous flower and being highly attracted by the volatile floral of the species. The strict dependence on pollinators for their reproduction, associated with the low frequency of sphingids, it led to a high pollen limitation in the studied population. Considering the behavior of these floral visitors, this work shows that the plant-sphingid and plant-beetle interactions are mediated by the same floral volatiles, resulting in an important trade-off between the attraction of pollinators and the main florivores. Although this interaction can be detrimental to the plant's fitness, the occurrence of self-compatibility allows sphingids’ visits, even if infrequent, to be extremely efficient.
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Ecologia, Polinização, Escarabeídeo, Lepidóptero, Botânica