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Bees make choices about what flowers to visit among the options in the floral market. Bee specialization to visit only one plant species at a time is relevant to maintain the plant-bee mutualism. angiosperms derive a clear benefit in their sexual reproduction from the fidelity exhibited by the bees; less obvious is why the insects engage in this behavior. The phenomenon of flower constancy in bees is known from more than two millennia ago yet there is no general theory that can explain all kinds of flower constancy. In this paper I review different theories on flower constancy, providing evidence in favor and against each model, and then I discuss the possible scenario in which each behavior can have an ecological advantage. Finally, I present evidence of flower constancy exhibited by other groups of insects and vertebrate pollinators.

AMAYA-MÁRQUEZ, M. (2009). Floral constancy in bees: a revision of theories and a comparison with other pollinators. Revista Colombiana De Entomología, 35(2), 206–216. https://doi.org/10.25100/socolen.v35i2.9221

AMAYA MÁRQUEZ M. 1991. Análisis Palinológico de la Flora del Parque Nacional Natural Amacayacu (Amazonas) visitada por colibríes (Aves: Trochilidae). Trabajo de grado, Departamento Biología, Facultad de Ciencias, Universidad Nacional de Colombia. Bogotá, D. C. 60 p. 214 Revista Colombiana de Entomología Marisol Amaya-Márquez

AMAYA MÁRQUEZ ,M.; STILES , F. G.; RANGEL , J. O. 2001. Interacción planta-colibrí en Amacayacu (Amazonas, Colombia): Una perspectiva palinológica. Caldasia 23 (1): 301-322.

AMAYA -MÁRQUEZ , M.; HILL , P. S. M.; BARTHEL , J. F.; PHAM, L. L.; DOTY, D. R.; WELLS , H. 2008. Learning and memory during foraging of the blue orchard bee, Osmia lignaria Say (Hymenoptera: Megachilidae). Journal of the Kansas Entomological Society 81 (4): 315-327.

BENÉ, F. 1941. Experiments on the color preference of the blackchinned hummingbird. Condor 43 (5): 237-242.

BENÉ, F. 1945. The role of learning in the feeding behavior of black-chinned hummingbirds. Condor 47 (1): 3-22.

BERNAL, R.; ER VIK, F. 1996. Floral biology and pollination of the dioecious palm Phytelephas seemannii in Colombia: An adaptation to staphylinid beetles. Biotropica 28 (4b): 682-696.

BOLTEN, A. B.; FEINSINGER , P. 1978. Why do hummingbird flowers secrete dilute nectar? Biotropica 10 (4): 307-309.

BRONSTEIN, J. L. 1995. The plant-pollinator landscape, pp. 256-288. In: Hansson, L.; Fahrig, L.; Merriam, G. (Eds.). Mosaic Landscapes and Ecological Processes. Chapman & Hall, London, UK.

ÇAKMAK, I.; WELLS , H. 1995. Honeybee Forager individual Constancy: Innate or Learned? BeeScience 3: 165-174.

ÇAKMAK, I.; WELLS , H. 2001. Reward frequency: effects on flower choices made by different honeybee subspecies endemic to Turkey. Turkish Journal of Zoology 25: 169-176.

CHITTKA, L. 1992. The colour hexagon: A chromaticity diagram based on photoreceptor excitations as a generalized representation of colour opponency. Journal of Comparative Physiology A 170 (5): 533-543.

CHITTKA, L.; THOMPSO N, J. D. 1997. Sensori-motor learning and its relevance for task specialization in bumblebees. Behavioral Ecology and Sociobiology 41 (6): 385-398.

CHITTKA, L.; KEVAN, P. G. 2005. Flower colour as advertisement, pp. 157-196. In: Dafni, A.; Kevan, P. G.; Husband, B. C. (Eds.). Practical Pollination Biology. Enviroquest, Ltd. Cambridge, Ontario, Canada.

CHITTKA, L.; GUMBER T, A.; KUNZE , J. 1997. Foraging dynamics of bumblebees: Correlates of movements within and between plant species. Behavioral Ecology 8 (3): 239-249.

CHITTKA, L.; THOMSO N, J. D.; WASER , N. M. 1999. Flower constancy, insect psychology, and plant evolution. Naturwissenschaften 86 (8): 361-377.

CREPET, W. L.; FRIIS, E. M.; NIXON, K. C.; LACK, A. J.; JARZE MBOWSKI, E. A. 1991. Fossil Evidence for the Evolution of Biotic Pollination. Philosophical Transactions: Biological Sciences 333 (1267): 187-195.

CUNNINGHAM, J. P.; MOORE , C.J.; ZALUCKI, M. P.; WES T, S. A. 2003. Learning, odour preference and flower foraging in moths. The Journal of Experimental Biology 207 (1): 87-94.

DAFNI, A.; BERNHAR DT, P.; SHMIDA, A.; IVRI, Y; GREE NBAU M, S.; O’TOOLE , C.; LOS ITO, L. 1990. Red bowl-shape flowers: convergence for beetle pollination in the Mediterranean region. Israel Journal of Botany 39 (1-2): 81-92.

DARWIN, C. 1876. On the effects of cross and self fertilization in the vegetable kingdom. John Murray, London, UK. 482 p.

DE LOS MOZOS , PASCUAL M.; DOMINGO, L. M. 1991. Flower constancy in Heliotaurus ruficollis (Fabricious 1781), Coleoptera, Alleculidae. Elytron 5: 9-12.

DUKAS , R.; ELLNER , S. 1993. Information processing and prey detection. Ecology 74 (5): 1337-1346.

DUKAS , R.; WASER , N. 1994. Categorization of food types enhances foraging performance of bumblebees. Animal Behaviour 48 (5): 1001-1006.

ENDLER , J. A. 1981. An overview of the relationships between mimicry and crypsis. Biological Journal of the Linnean Society 16 (1): 25-31.

ENDRESS , P. K. 1994. Diversity and evolutionary biology of tropical flowers. Cambridge University Press, Cambridge, UK. 511 p.

ENGLUND, R. 1993. Movement patterns of Cetonia beetles (Scarabaeidae) among flowering Viburnum opulus (Caprifoliaceae). Oecologia 94 (2): 295-302.

ERIKSSO N, R. 1994. The remarkable weevil pollination of the neotropical Carludovicoideae (Cyclanthaceae). Plant Systematics and Evolution 189 (1-2): 75-81.

FAEGRI, K.; VAN DER PILJ, L. 1979. The principles of Pollination Ecology. Pergamon Press Ltd., Oxford, UK. 244 p.

FEISINGER , P. 1978. Ecological interactions between plants and hummingbirds in a succesional tropical community. Ecological Monographs 48 (3): 269-287.

FENSTER , C. B.; W. S. ARMBRUS TER , W. S.; WILSO N, P.; DUDAS H, M. R.; THOMSO N, J. D. 2004. Pollination syndromes and floral specialization. Annual Review of Ecology, Evolution, and Systematics 35: 375-403.

FLEMING, T. H. 1992. How do fruitand nectar-feeding birds and mammals track their food resources?, pp. 355-391. In: Hunter, M. D.; T. Ohgashi; P. W. Price, P. W. (Eds.). Effects of resource distribution on animal-plant interactions. Academic Press, New York.

FRANKIE, G. W.; BAKER , H. G. 1974. The importance of pollinator behavior in the reproductive biology of tropical bees. Anales del Instituto de Biología, Universidad Nacional Autónoma de México 45 (1): 1-10.

FREE , J. B.; WILLIAMS, I. H. 1973. The pollination of hybrid kale, Brassica oleraceae L. Journal of Agricultural Science 81: 557-559.

FREE , J. B.; WILLIAMS, I. H. 1983. Foraging behavior of honeybees and bumblebees on Brussels sprout grown to produce hybrid seed. Journal of Apicultural Research 22 (2): 94-97.

FUKUSHI, T. 1973. Classical conditioning in the housefly, Musca domestica. Annotationes Zoologicæ Japonenses 46: 135-143.

FUKUSHI, T. 1989. Learning and discrimination of coloured papers in the walking blowfly, Lucilia cuprina. Journal of Comparative Physiology A 166 (1): 57-64.

GARDENER , M. C.; GILLMAN, M. P. 2002. The taste of nectar neglected area of pollination ecology. Oikos 98 (3): 552-557.

GASS , C. E.; SUTHERLAND, G. D. 1985. Specialization by territorial hummingbirds on experimental enriched patches of flowers: energetic profitability and learning. Canadian Journal of Zoology 63: 2125-2133.

GEGEAR , R. J.; LAVERTY, T. M. 1998. How many flower types can bumble bees forage on at the same time. Canadian Journal of Zoology 76 (7): 1358-1365.

GEGEAR , R. J.; LAVERTY, T. M. 2004. Effect of a colour dimorphism on the flower constancy of honey bees and bumble bees. Canadian Journal of Zoology 82 (4): 587-594.

GENTRY , A. H. 1974. Flowering phenology and diversity in tropical Bignoniaceae. Biotropica 6 (1): 64-68.

GEORGE, M. W. 1980. Hummingbird foraging behavior at Malvaviscus arboreous var. drummondii. Auk 97: 790-794.

GILBER T, L. E. 1975. Ecological consequences of a coevolved mutualism between butterflies and plants, pp. 210-240. In: Gilbert, L. E.; Raven, P. H. (Eds.). Coevolution of Animal and Plants. University of Texas Press, Austin, Texas.

GILL , F. B. 1988. Trapline foraging by hermit hummingbirds: Competition for an undefended, renewable resource. Ecology 69 (6): 1933-1942.

GOLDSMITH, T. H.; GOLDSMITH, K. M. 1979. Discrimination of colors by the black-chinned hummingbird, Archilochus alexandri. Journal of Comparative Physiology 130: 209-220.

GÓMEZ , J. M. 2002. Generalización en las interacciones entre plantasy polinizadores. Revista Chilena de Historia Natural 75: 105-116.

GORDON, W. F.; Opler, P. A.; Bawa, K. S. 1976. Foraging ofsolitary bees: Implications for out crossing of a neotropical forest. Journal of Ecology 64: 1049-1057.

GOULD, J. L. 1987. Honey bees store learned flower-landing behavioraccording to time of the day. Animal Behaviour 35 (5): 1579-1581. Floral constancy in bees 215.

GOULD, J. L. 1991. The ecology of honeybee learning, pp.306-321. In: Goodman, L. J.; R. C. Fisher (Eds.). The behavior and physiology of bees. CAB International, Wallingford, UK.

GOULSON, D. 2000. Are insects flower constant because they usesearch images to find flowers?. Oikos 88 (3): 547-552.

GOULSON, D. 2003. Bumblebees. Their Behavior and Ecology. Oxford University Press, New York. 235 p.

GOULSON, D.; WRIGHT, N. P. 1998. Flower constancy in the hoverflies Episyrphus balteatus (Degeer) and Syrphus ribesii (L.) (Syrphidae). Behavioral Ecology 9 (3): 213-219.

GOULSON, D.; STOU T, J. C; HAWSON, S. A. 1997. Can flower constancy in nectaring butterflies be explained by Darwin’s interference hypothesis? Oecologia 112 (2): 225-232.

GRANT, V. 1949. Pollination systems as isolating mechanisms in angiosperms. Evolution 3 (1): 82-97.

GRANT, V. 1950. The flower constancy of bees. The Botanical Review 16 (7): 379-398.

GREGGERS , U.; MENZEL , R. 1993. Memory dynamics and foraging strategies of the honeybee. Behavioral Ecology and Sociobiology 32 (1): 17-29.

GREGGERS , U.; MAUELSHAGEN, J. 1997. Matching behavior of honeybees in a multiple-choice situation: The differential effect of environmental stimuli on the choice process. Animal Learning & Behavior 25 (4): 458-472.

GUMBER T, A. 2000. Color choices by bumble bees (Bombus terrestris): Innate preferences and generalization after learning. Behavioral Ecology and Sociobiology 48 (1): 36-43.

HEALY , S. D.; HURLEY , T. A. 1995. Spatial memory in rufuos hummingbirds (Selasphorous rufus): a field test. Animal Learning & Behavior 23: 63-68.

HEALY , S. D.; HURLEY , T. A. 1998. Hummingbirds’ memory for flower: patterns or actual spatial location? Journal of Experimental Psychology: Animal Behavior Processes 24: 1-9.

HEALY , S. D.; HURLEY , T. A. 2001. Foraging and spatial learning in hummingbirds, pp. 127-147. In: Chittka, L.; J. D. Thomson, J. D. (Eds.). Cognitive Ecology of Pollination: Animal behavior and floral evolution. Cambridge University Press, Cambridge, UK.

HEINRICH, B. 1975. Bee flowers: A hypothesis on flower variety and blooming times. Evolution 29 (2): 325-335.

HEINRICH, B. 1976a. Bumblebee foraging and the economics of sociality. American Scientist 64 (4): 384-395.

HEINRICH, B. 1976b. The foraging specialization of individual bumble bees. Ecological Monographs 46 (2): 105-128.

HEINRICH, B. 1979. Majoring and minoring by foraging bumblebees, Bombus vagas: An experimental analysis. Ecology 60 (2): 245-255.

HEINRICH, B. 1983. Do bumblebees forage optimally, and does it matter? American Zoologist 23 (2): 273-281.

HEINRICH, B.; MUDGE, P. R.; DERINGIS, P. G. 1977. Laboratory analysis of flower constancy in foraging bumble bees: Bombus ternarious and B. terricola. Behavioral Ecology and Sociobiology 2 (3): 247-265.

HEITHAUS , E. R.; FLEMING, T. H.; OPLER , P. A. 1975. Foraging patterns and resource utilization in seven species of bats in a seasonal tropical forest. Ecology 56 (4): 841-854.

HERNÁNDEZ DE SALOMON, C.; SPATZ, H-C. 1983. Colour vision in Drosophila melanogaster: wavelength discrimination. Journal of Comparative Physiology 150 (1): 31-37.

HILL , P. S. M.; WELLS , P. H.; WELLS , H. 1997. Spontaneous flower constancy and learning in honey bees as a function of colour. Animal Behaviour 54 (3): 615-628.

HILL , P. S. M.; HOLLIS, J.; WELLS , H. 2001. Foraging decisions in nectarivores: Unexpected interactions between flower constancy and energetic rewards. Animal Behaviour 62 (4): 729-738.

HURLEY , T. A.; HEALY , S. D. 1996. Location or local visual cues? Memory for flowers in rufous hummingbirds. Animal Behaviour 51 (5): 1149-1157.

JANZEN, D. H. 1971. Euglossine bees as long-distance pollinators of tropical plants. Science 171 (3967): 203-205.

JOHNSON, S. D. 1994. Evidence for Batesian mimicry in a butterfly-pollinated Orchid. Biological Journal of the Linnean Society 53:91-104[S].

KANDORI, I.; OHSAKI, N. 1996. The learning abilities of the white cabbage butterfly, Pieris rapae, foraging for flowers. Researches on Population Ecology 38 (1): 111-117.

KEASAR , T.; MOTRO , U.; SHUR , Y.; SHMIDA, A. 1996. Overnight memory retention of foraging skills by bumblebeesis imperfect. Animal Behaviour 52 (1): 95-105.

KELBER , A. 1996. Colour learning in the hawkmoth Macroglossum stellatarum. The Journal of Experimental Biology 199 (5): 1127-1131.

KELBER , A.; PFAFF, M. 1997. Spontaneous and learned preferences for visual flower in a diurnal moth. Israel Journal of Plant Sciences 45:235-246.

KLOSTERHALFEN, S.; FISHER , W.; BITTERMAN, M. E. 1978. Modification of attention in honey bees. Science 201 (4362): 1241-1243.

KODRIC-BROWN, A.; BROWN, J. H. 1978. Influence of economics, interspecific competition, and sexual dimorphism on territoriality of migrant rufous hummingbirds. Ecology 59 (2): 285-296.

KOLTERMANN, R. 1974. Periodicity in the activity and learning performance of the honeybee, pp. 218-236. In: Browne, L. B. (Ed.). Experimental Analysis of Insect Behaviour. SpringerVerlag, New York.

KUNIN, W. E. 1993. Sex and the single mustard: population density and pollinator behavior effects on seed-set. Ecology 74 (7): 2145-2160.

LARSON, B.; KEVAN, P. G.; INOUYE , D. W. 2001. Flies and flowers. I. The taxonomic diversity of anthophilous and pollinating flies. Canadian Entomologist 133 (4): 439-465.

LAVERTY, T. M. 1980. The flower-visiting behavior of bumble bees: Floral complexity and learning. Canadian Journal of Zoology 58 (7): 1324-1335.

LAVERTY, T. M. 1994. Costs to foraging bumble bees of switching plant species. Canadian Journal of Zoology 72 (1): 43-48.

LAVERTY, T. M.; PLOWRIGHT, R. C. 1988. Flower handling by bumble bees: A comparison of specialists and generalists. Animal Behaviour 36: 733-740.

LAWRENCE, E. S.; ALLE N, J. A. 1983. On the term ‘search image’. Oikos 40: 313-314.

LEWIS, A. C. 1986. Memory constraints and flower choice in Pieris rapae. Science 232 (4752): 863-865.

LEWIS, A. C. 1989. Flower visit consistency in Pieris rapae, the cabbage butterfly. Journal of Animal Ecology 58 (1): 1-13.

LEWIS, A. C. 1993. Learning and the evolution of resources: Pollinators and flower morphology, pp. 219-242. In: Papaj, D. R.; Lewis, A. C. (Eds.). Insect learning: Ecological and evolutionary Perspectives. Chapman & Hall, Inc, London, UK.

LISTABAR TH, C. 1996. Pollination of Bactris by Phyllotrox and Epurea: implications of the palm breeding beetles on pollination at the community level. Biotropica 28 (1): 69-81.

MACHADO, C. A.; ROBBINS, N.; THOMAS , M.; GILBERT, P; HERRE , E. A. 2005. Critical review of host specificity and its coevolutionary implications in the fig/fig-wasp mutualism, pp. 120-142. In: Hey, J.; W. M. Fitch; Ayala, F. J. (Eds.). Systematics and the origin of species. On Ernst Mayr’s 100th Anniversary. The National Academies Press. Washington, D. C.

MARDEN, J. H.; WADDINGTON, K. D. 1981. Floral choices by honey bees in relation to the relative distances to flowers. Physiological Entomology 6 (4): 431-435.

MELÉNDEZ -ACKERMAN, E.; CAMPBELL , D. R.; WASER , N. W. 1997. Hummingbird behavior and mechanisms of selection on flower color in Ipomopsis. Ecology 78 (8): 2532-2541.

MENZEL , R. 1979. Behavioral access to short-term memory in bees. Nature 281:368-369.

MENZEL , R. 1985. Learning in honey bees in an ecological and behavioral context, pp. 55-74. In: Hölldobler, B.; Lindauer, M. (Eds.). Experimental Behavioral Ecology and Sociobiology: in 216 Revista Colombiana de Entomología Marisol Amaya-Márquez Memoriam Karl von Frisch 1886-1982. Erlbaum Associates. Hillsdale, New Jersey.

MENZEL , R. 1999. Memory dynamics in the honeybee. Journal of Comparative Physiology A 185 (4): 323-340.

MENZEL , R. 2001. Behavioral and neural mechanisms of learning and memory as determinants of flower constancy, pp. 21-40. In: Chittka, L.; Thomson, J. D. (Eds.). Cognitive ecology of pollination. Animal behavior and floral evolution. Cambridge University Press, Cambridge, UK.

MENZEL , R.; ERBER , J. 1978. Learning and memory in bees. Scientific American 239 (1): 102-111.

MENZEL , R.; ERBER , J.; MASUHR, T. 1974. Learning and memory in the honeybee, pp. 195-217. In: Browne, L. B. (Ed.). Experimental Analysis of Insect Behaviour. Springer-Verlag, New York.

MEVI-SCHUTZ, J.; GOVER DE, M.; ERHAR DT, A. 2003. Effects of fertilization and elevated CO2 on larval food and butterfly nectar aminoacid preference in Coenonympha pamphilus L. Behavioral Ecology and Sociobiology 54 (1): 36-43.

MICHENER , C. D. 2000. The bees of the World. The Johns Hopkins University Press, Baltimore, Maryland. 913 p.

MILLER , R. S.; MILLER , R. E. 1971. Feeding activity and color Preferences of ruby-throated hummingbirds. Condor 73 (3): 309-313.

MILLER , R. S.; TAMM, S.; SU THERLA ND, D. G.; GASS , C. L.1985. Cues for orientation in hummingbird foraging: Color and position. Canadian Journal of Zoology 63 (1): 18-21.

NUÑEZ -AVELLANEDA, L. A.; ROJAS -ROBLES , R. 2008. Biología reproductiva y ecología de la polinización de la palma milpesos Oenocarpus bataua en los andes colombianos. Caldasia 30 (1): 101-125.

PELLMYR , O.; PATT, J. 1986. Function of olfactory and visual stimuli in pollination of Lysichiton americanum (Araceae) by a staphylinid beetle. Madroño 33 (1): 47-54.

PERCIVAL , M. 1965. Floral Biology. Pergamon Press Ltd., Oxford, UK. 243 p.

PLEASANTS, J. M. 1981. Bumblebee response to variations in nectar availability. Ecology 62 (6): 1648-1661.

PROCTOR , M.; YEO , P.; LACK, A. 1996. The natural history of pollination. Timber Press, Portland, Oregon. 479 p.

PROKOPY, R. J.; AVERILL , A. L.; COOLEY , S. S.; ROITBER G, C. A. 1982. Associative learning in egg-laying site selection by apple maggot flies. Science 218 (4567): 76-77.

PYKE, G. H. 1978. Are animals efficient harvesters? Animal Behaviour 26: 241-251.

PYKE, G. H. 1979. Optimal foraging in bumblebees: Rules of movement between flowers within inflorescences. Animal Behaviour 27: 1167-1181.

PYKE, G. H.; PULLIAM, H. R.; CHARNOV, E. L. 1977. Optimal foraging: A selective review of theory and tests. The Quarterly Review of Biology 52 (2): 137-155.

REAL , L. A. 1981. Uncertainty and pollinator-plant interactions: The foraging behavior of bees and wasps on artificial flowers. Ecology 629 (1): 20-26.

SANDERSO N, C. E.; OROZCO, B. S.; HILL , P. S. M.; WELLS , H. 2006. Honeybee (Apis mellifera ligustica) response to differences in handling time, rewards, and flower colours. Ethology 112 (10): 937-946.

SEELEY , T. D. 1985. The information-center strategy of honeybee foraging. Fortschritte der Zoologie 31: 75-90.

SPATZ, H-C.; RE ICHER T, H. 1974. Associative learning of Drosophila melanogaster. Nature 248: 359-361.

STEPHENS, D. W.; KRE BS, J. R. 1986. Foraging Theory. Princeton University Press. Princeton, New Jersey. 247 p.

STILES , F. G. 1976. Taste preferences, color preferences and flower choice in hummingbirds. Condor 78 (1): 10-26.

STILES , F. G. 1981. Geographical aspects of bird-flower coevolution, with particular reference to Central America. Annals of the Missouri Botanical Garden 68 (2): 323-351.

SWIHART, C. A. 1971. Colour discrimination by the butterfly, Heliconious charitonious Linn. Animal Behaviour 19: 156-164.

SWIHART, C. A.; SWIHART, S. L. 1970. Colour selection and learned feeding preferences in the butterfly, Heliconious charitonious Linn. Animal Behaviour 18: 60-64.

THOMSON, J. D.; PETERSON, S. C.; HARDER , L. D. 1987. Response of traplining bumble bees to competition experiments: Shifts in feeding location and efficiency. Oecologia 71 (2): 295-300.

TINBERGEN, L. 1960. The natural control of insects in pinewoods. I. Factors influencing the intensity of predation by songbirds. Archives Neerlandaises de Zoologie 13: 266-343.

TROJE, N. 1993. Spectral categories on the learning behavior of blowflies. Zeitschrift Fur Naturforschung 48 (1-2): 96-104.

WADDINGTON, K. D.; HOLDEN, L. R. 1979. Optimal foraging: On flower selection by bees. The American Naturalist 114 (2): 179-196.

WADDINGTON, K. D.; GOTTLIEB, N. 1990. Actual vs. perceived profitability: A study of floral choice of honey bees. Journal of Insect Behavior 3 (4): 429-441.

WALLER , D. A.; GILBERT, L. E. 1982. Roost recruitment and resource utilization: observations on Heliconius charitonious L. roost in Mexico. Journal of the Lepidopterists’ Society 36 (3): 178-184.

WASER , N. M. 1979. Pollinator availability as a determinant of flowering time in Ocotillo (Fouquieria splendens). Oecologia 39 (1): 107-121.

WASER , N. M. 1983. Competition for pollination and floral character differences among sympatric plant species: A review of evidence, pp. 277-309. In: Jones, C. E.; Little, R. J. (Eds.). Handbook of experimental pollination biology. Van Nostrand Reinhold Company Inc., New York.

WASER , N. M. 1986. Flower constancy: Definition, cause, and measurement. The American Naturalist 127 (5): 593-603.

WASER , N. M.; CHITTKA, L.; PRICE, M. V.; WILLIAMS, N. M.; OLLERTON, J. 1996. Generalization in pollination systems, and why it matters. Ecology 7794: 1043-1060.

WEISS , M. R. 1995. Associative colour learning in a nymphalid butterfly. Ecological Entomology 20 (3): 298-301.

WEISS , M. R. 1997. Innate colour preferences and flexible colour learning in the Pipevine swallowtaill. Animal Behaviour 53 (5): 1043-1053.

WEISS , M. R. 2001. Vision and learning in some neglected pollinators: beetles, flies, moths, and butterflies pp. 171-190. In: Chittka, L.; Thomson, J. D. (Eds.). Cognitive ecology of pollination. Animal behavior and floral evolution. Cambridge University Press, Cambridge, UK.

WELLS , H.; WELLS , P. H. 1983. Honey bee foraging ecology: Optimal diet, minimal uncertainty or individual constancy? Journal of Animal Ecology 52 (3): 829-836.

WELLS , H.; WELLS , P. H. 1984. Can honey bees change foraging patterns? Ecological Entomology 9(4): 467-473.

WELLS , H.; WELLS , P. H. 1986. Optimal diet, minimal uncertainty and individual constancy in the bee Apis mellifera. Journal of Animal Ecology 55 (3): 881-891.

WELLS , H.; HILL , P. S. M.; WELLS , P. H. 1992. Nectarivore foraging ecology: Rewards differing in sugar types. Ecological Entomology 17 (3): 280-288.

WEST-EBERHAR D, M. 2003. Developmental Plasticity and Evolution. Oxford University Press, Inc., New York. 794 p.

WOODWAR D, G. L.; LAVERTY, T. M. 1992. Recall of flower handling skills by bumble bees: a test of Darwin’s interference hypothesis. Animal Behaviour 44 (6): 1045-1051.

YOU NG, H. J. 1986. Beetle pollination of Dieffenbachia longispatha (Araceae). American Journal of Botany 73 (6): 931-944.