Summary
Bumble bees (Bombus spp.) picked up a pollen packet (pollinium) of milkweed (Asclepias syriaca L.) every 2–5 h, usually more rapidly on their feet than on their mouthparts. Pollinia were retained an average of slightly over one day on the mouthparts and one-quarter day on the feet. This long retention period enhances the possibility of outcrossing in this largely or completely self-incompatible species. Although many more pollinia were carried on the feet, the longer retention of those on the mouthparts resulted in their collective outcrossing potential exceeding that of pollinia on the feet. Once pollinia became attached to the bees (via their attachment mechanisms, the corpuscula), others often attached to the translator arms (connecting corpusculum with pollinia) of the first pollinia. Long strings of pollinia and corpuscula often resulted, but they frequently were shed down to a single corpusculum, which was usually retained for long periods (estimated retention time=12–43 days). During the middle and latter part of the flowering period about two-thirds of the bees' feet carried only a single corpusculum. Feet in this condition picked up extremely few pollinia and thus were largely unavailable as sites for pollen transfer. Having several single corpuscula on the feet greatly lowered the number of pollinia carried by a bee over the season. Single corpuscula occurred much less frequently on the mouthparts and were shed over 25 times as rapidly as those on the feet. Many more bumble bees moved between clones than did other possible diurnal pollinators, largely a result of being several times more abundant than all other visitors combined. This factor, plus their heavy pollinia load, suggests that they were the most important diurnal pollinators of these clones.
Similar content being viewed by others
References
Bertin RI, Willson MF (1980) Effectiveness of diurnal and nocturnal pollination of two milkweeds. Can J Bot 58:1744–1746
Frankie GW, Opler PA, Bawa KS (1976) Foraging behaviour of solitary bees: implications for outcrossing of a neotropical forest tree species. J Ecol 64:1049–1057
Free JB, Butler CG (1959) Bumblebees. Collins London
Handel SN (1976) Restricted pollen flow of two woodland herbs determined by neutron-activation analysis. Nature 260:422–423
Heinrich B (1979) “Majoring” and “minoring” by foraging bumblebees, Bombus vagans: an experimental analysis. Ecology 60:245–255
Levin DA, Berube D (1972) Pholox and Colias: the efficiency of a pollination system. Evolution 26:242–250
Levin DA, Kerster HW (1974) Gene flow in seed plants. Evol Biol 7:139–220
Linhart YB (1973) Ecological and behavioral determinants of pollen dispersal in hummingbird-pollinated Heliconia. Amer Natur 107:511–523
Lynch SP (1977) The floral ecology of Asclepias solanoana Woods. Madroño 24:159–177
Macior LW (1965) Insect adaptation and behavior in Asclepias pollination. Bull Torrey Bot Club 92:114–126
Morse DH (1977) Resource partitioning in bumblebees: the role of behavioral factors. Science 197:678–680
Morse DH (1981a) Modification of bumblebee foraging: the effect of milkweed pollinia. Ecology 62:89–97
Morse DH (1981b) Prey capture by the crab spider Misumena vatia (Clerck) (Thomisidae) on three common native flowers. Amer Midl Natur 105:358–367
Morse DH, Fritz RS (in press) Experimental and observational studies of patch choice at three scales by the crab spider Misumena vatia. Ecology
Reincke DC, Bloom WL (1979) Pollen dispersal in natural populations: a method for tracking individual pollen grains. Syst Bot 4:223–229
Robertson C (1887a) Insect relations of certain asclepiads. II. Bot Gaz 12:244–250
Robertson C (1887b) Insect relations of certain asclepiads. I. Bot Gaz 12:207–216
Schlising RA, Turpin RA (1971) Hummingbird dispersal of Delphinium cardinale pollen treated with radioactive iodine. Amer J Bot 58:401–406
Schmitt J (1980) Pollinator foraging behavior and gene dispersal in Senecio (Compositae). Evolution 34:934–943
Snodgrass RE (1956) Anatomy of the honey bee. Cornell University Press Ithaca New York
Thomson JD, Plowright RC (1980) Pollen carryover, nectar rewards, and pollinator behavior with special reference to Diervilla lonicera. Oecologia (Berl) 46:68–74
Wiklund C, Eriksson T, Lundberg H (1979) The wood white butterfly Leptidea sinapis and its nectar plants: a case of mutualism or parasitism? Oikos 33:358–362
Woodson RE (1954) The North American species of Asclepias L. Ann Missouri Bot Gard 41:1–211
Wyatt R (1976) Pollination and fruit-set in Asclepias: a reappraisal. Amer J Bot 63:845–851
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Morse, D.H. The turnover of milkweed pollinia on bumble bees, and implications for outcrossing. Oecologia 53, 187–196 (1982). https://doi.org/10.1007/BF00545662
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00545662