Blue tits, Parus caeruleus, as pollinators of the crown imperial, Fritillaria imperialis, in Britian

Until the last decade there were no records of bird pollination in Europe (e.g., Proctor and Yeo 1973). Evidence of birds visiting flowers in Europe was collected by Ford (1985). He discussed the various hypotheses proposed to explain this apparent lack of passerine-bird pollination. In Europe the idea that birds visit flowers to catch insects or to eat fleshy parts of the flowers, rather than to drink nectar, is much more deeply ingrained than in any other region (e.g., Lowe 1896, Swynnerton 1916, Campbell 1963). This situation is similar to that prevalent in Australia ca. 15 yr ago, when most ornithologists thought that honeyeaters visited the flowers to eat in-sects rather than to drink nectar (H. A. Ford, pers. comm.) The behaviour of birds visiting flowers or exploiting new sources of food, such as the sap of dam-aged trees (Mylne 1959, Soper 1969), or milk in bottles (Fisher and Hinde 1949, Hinde and Fisher 1952), has been described as novel or unusual (Thorpe 1956). From the point of view of a floral ecologist, the development of new forms of search and the variation in the exploitation patterns are expected from a pollinator. Blue tits (Parus caeruleus) have been repeatedly recorded as flower visitors throughout Europe (e .g., Ford 1985, Kay 1985). They have been described as using a wide variety of habitats (Perrins 1979, Gibb 1954), and as resorting to new and unusual ways of foraging (Thorpe 1956, Fisher and Hinde 1949, Hinde and Fisher 1952)

Distributional Limits of Euglossine and Meliponine Bees (Hymenoptera: Apidae) in Northwestern Mexico

Euglossine and meliponine bees are predominantly distributed within the American tropics (Dressler, R.L. 1982. Ann. Rev. Ecol. Syst., 13: 373-384; Roubik, D.W. 1989. Ecology and Natural History of Tropical Bees. Cambridge, Univ. Press). Despite the extensive collections of euglossine bees with chemical baits, few extra-tropical records have been reported (Moure, J.S. 1967. At. Simp. Biota Amazon., 5: 395-415; Kimsey, L.S. & Dressler, R.L. 1986. Pan-Pacific Entomol., 62: 229-236; Kimsey, L.S. 1987. Syst. Entomol., 12: 63-72). Nevertheless, some species occur outside the geographic tropics. In South America there are reports of euglossine and meliponine bees as far south as 32° S (Moure 1967. Wittmann, D., Hoffmann, M. & Scholz, E. 1988. Entomol. Generalis, 14: 53-60), but in the Northern Hemisphere it has been thought, until recently, that their distribution was restricted to about 25° N (Roubik 1989), in the Sierra Madre Oriental and central Mexico. During the summers of 1991 and 1993 to 1995 bee collections have been made in several localities in southern Sonora, Mexico (Table 1). These include Nannotrigona perilampoides (Cresson), and Euglossa viridissima Friese. The former has been collected in wild nests in trunks of Jpomoea arborescens (Humb. & Bonpl. ex Willd.) G. Don in the Sierra de Alamos, and from domestic hives kept by Rafael Figueroa at his carpentry in Alamos, Sonora. Male and female specimens of Eg. viridissima have been collected visiting flowers of Tecoma stans (L.) Juss ex H.B.K. and Thevetia peruviana (Pers.) Scum ex Engler & Prantl. However, other plants known to be visited and pollinated almost strictly by euglossine bees are present in the area. These include a large complement of orchids, tropical trees, and vines like Dalechampia scandens L. (Armbuster, W.S. & Webster, G.L. 1979. Biotropica, 11: 278-283) that are known to be used by euglossine and meliponine bees as food, and also as fragrance and resin sources for attraction and nest building. Males of euglossine bees were also lured with fragrances of eugenol, methyl salycilate, vanillin, and eucalyptol. However, in this study they were only attracted to eugenol

Distributional limits of euglossine and meliponine bees (Hymenoptera: Apidae) in northwestern Mexico

Volume: 73Start Page: 137End Page: 14

Biologia de Poblaciones Silvestres y Cultivadas de Phaseolus Coccineus L: I. Relaciones Planta-Palinizador

Diferentes autores han enfatizado la respuesta adaptativa existente entre diferentes grupos de arreglos de las partes florales y sus correspondientes polinizadores, de tal forma que se ha establecido una aceptable correlacion entre estos, denominandolos sindromes de polinizacion (Delpino, 1868-1875;Grant, 1963;Pijl, 1960, 1961; Faegri & Pijl, 1971 Balcer & Hurd, 1968). Asi por ejemplo, se ha encontrado que la gran mayoria de las flores de color rojo con corolas tubulares, carentes de color y con una abundante produccion de nectar son polinizadas generalmente por aves, siendo el caso mas conocido el de los colibries. Se ha encontrado ademas, que la concentracion del nectar juega un importante papel, de tal manera que en cada grupo de polinizadores tenemos una concentracion caracteristica de azucares en el nectar, siendo del orden del 25% para abejas y abejorros, mientras que para colibries es tan solo del 21 % (Baker, 1975). Para explicar esto se han propuesto variadas hipotesis, de las cuales la mas plausible parece ser la emitida por Bolten & Feinsinger (1978), quienes dicen que las abejas no visitan flores connectares diluidos por el alto costo involucrado en concentrarlo para convertirlo en miel, de tal forma que las bajas concentraciones del nectar presente en las flores ornit6filas son parte del mecanismo de exclusion de abejas, relajandose la competencia entre ambos grupos de polinizadores. Finalmente, los diferentes criterios fenologicos y de habitat parecen ser de gran importancia en el aislamiento reproductivo de poblaciones naturales; ligeros despla-zamientos temporales en la floracion, o espaciales en distribucion, pueden producir cambios drasticos en la fauna de polinizadores acompafiantes yen el flujo genetico entre poblaciones (Ehrlich & Raven, 1969; Mosquin, 1971 )

Do flowers reabsorb nectar?

The rate of change in the standing crop of nectar allowed to accumulate in flowers, described here as the apparent secretion rate, can be resolved into two components: gross secretion rate and apparent reabsorption rate. A simple model shows how changes in these component rates may affect the apparent secretion rate. The ecological and physiological correlates of various temporal patterns of secretion are discussed in relation to whether the nectar carbohydrates originate from storage tissues or from immediate photosynthate

The pollination of Merremia palmeri (Convolvulaceae): can hawk moths be trusted?

The reproductive biology of Merremia palmeri and the pollination efficiency of its insect visitors were examined for a Sonoran Desert population in northwestern Mexico. Pollen transfer experiments proved that the plant is self-incompatible. Reproduction is, therefore, dependent upon reliable visitation by the primary pollinators, hawk moths. Many aspects of the floral structure are typical of sphingophilous flowers, and the time of flower opening and nectar secretion corresponded to the period of greatest hawk moth activity. A single hawk moth visit to a flower could be sufficient for successful fertilization. Additional visits up to five increased percentage fruit set, but flowers that received six or more visits had lower fruit and seed set. Neither the number of moth visits nor fruit and seed set were correlated with temperature or relative humidity. Over the course of the study 55% of flowers set fruit. We conclude that hawk moths are reliable and efficient pollinators for M. palmeri in a warm desert habita

Floral biology of a primary rain forest palm, Astrocaryum mexicanum Liebm.

Floral biology of a primary rain forest palm, Astrocaryum mexicanum Liebm. A detailed account of the changes in visitor numbers and behaviour, inflorescence phenology, and breeding systems is presented. lnflorescences open early in the morning (05.00 hours). Stigmas remain receptive for 15 h, while anther dehiscence occurs 20 h after inflorescence opening. Maximum pollen viability occurs the next day at 05.00 hours. This combination of features largely precludes self-pollination. Controlled pollinations show that apomixis and auto-pollination are absent, and indicate strong in compatibility. In contrast cross-pollinations do not differ in fruit set from open-pollinated controls. The fruit set in inflorescences exposed to pollinators for different periods after opening (and later stopping pollinator activity by fumigation), indicates that pollination occurs soon after inflorescence opening