No abstract

Floral scent of seven West African bat-pollinated tree species, belonging to six families, was collected in situ from flowering individuals using headspace adsorption. The seven species shared neither any specific compounds nor any other discernible pattern in their floral scent composition. Most of the identified compounds are common in the floral scent of species pollinated by a variety of animals. Adansonia digitata (Bombacaceae) was the only African species found to have a substantial proportion of sulphur compounds in its floral scent. This feature contrasts with the sampled New World bat-pollinated plants, which frequently contain these compounds. The floral scent of Ceiba pentandra (Bombacaceae), native to both South America and Africa, contained no sulphur substances, contradicting a previous study in the New World that identified the major floral compounds as dimethyl disulphide and dimethyl trisulphide. We suggest that the differences in the floral scent of C. pentandra, including the absence of sulphur compounds in the African variety, result from the different selective regimes exerted by the Pteropotidae bats, in Africa, and Phyllostomidae bats, in the New World, that visit their flowers.

The flower scents of 14 palm species were collected in the field in Ecuador and Puerto Rico by head‐space adsorption and analysed by gas chromatography‐mass spectrometry. Insect visitors were recorded in seven of the species in Ecuador. The floral scent of the different species was dominated by a variety of compounds, e.g., the fatty‐acid derived 3‐pentanone and the hydrocarbon series dodecane to pentadecane, the benzenoid compound 1,4‐dimethoxybenzene, the isoprenoids (E)‐ocimene, myrcene, linalool, and (E)‐α‐farnesene and the nitrogen‐containing compound 2‐methoxy‐sec‐butylpyrazine. Rather than mirroring the systematics of the studied palm species, the chemical composition of the floral scent reflected the pollination mode. The scent of beetle‐pollinated species was characterized by large amounts of one or a few dominant compounds, whereas fly‐ and bee‐pollinated species contained a mixture of several compounds in smaller total amounts. We suggest that specific scent compounds, as found in the beetle‐pollinated species, have evolved as a response to pollinator preferences. The importance of olfactory cues in relation to visual cues is higher in beetle‐pollinated species than in species pollinated by flies and bees.

Prestoea schultzeana is a monoecious, protandrous palm in the forest understory of Amazonian Ecuador. We studied its leaf production, population density, sexual expression, phenology, pollination, and the specificity of the floral visitors. On average, 1.4 leaves and 0.9 inflorescences are produced per individual per year. The number of staminate flowers per inflorescence is relatively constant compared with the number of pistillate flowers which varies greatly. Flowering occurs in staminate and pistillate phases of approximately 19 and 0–7 days duration, respectively. Flowers open in the morning, and staminate flowers abscise in the afternoon of the same day whereas pistillate flowers last for two days. Flowers are whitish‐yellow with a sweet odor and produce nectar. They were visited by Coleoptera (Chrysomelidae, Curculionidae, Nitidulidae, Ptiliidae, Staphylinidae), Hemiptera, Diptera (Drosophilidae, Syrphidae, Ceratopogonidae), Lepidoptera (Nymphalidae), and Hymenoptera (Formicidae, Halictidae). All examined individuals of the syrphid fly Copestylum sp. visiting pistillate flowers carried 100–500 grains of P. schultzeana pollen. Pollen occurred on all body parts, but especially on the legs, and this makes Copestylum sp. the most important pollinator. Most floral visitors were also frequent on the flowers of co‐occurring plant species; notably the palm Hyospathe elegans shared most visitor species with P. schultzeana.

Night‐flowering water lilies (Nymphaeaceae) in South America are pollinated by Cyclocephala scarab beetles (Scarabaeidae: Cyclocephalini) in a specialized relationship involving synchronized flowering movements, strong floral scent, food tissues, and heat‐producing flowers. We report that a similar and closely related association exists in West Africa between Nymphaea lotus L. and Ruteloryctes morio Fabricius (Cyclocephalini). This finding strongly supports a late Early Cretaceous origin of a symbiosis between the night‐flowering water lilies and pollinating Cyclocephalini beetles. We believe that this is the first unambiguous evidence of a plant‐pollinator relationship of this age. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 80, 539–543.