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Predicted pollen dispersal by honey-bees and three species of bumble-bees foraging on oil-seed rape: a comparison of three models

journal contribution
posted on 2023-05-18, 19:04 authored by Cresswell, JE, Andrew BassomAndrew Bassom, Bell, SA, Collins, SJ, Kelly, TB
  1. Comparisons among animal pollinators of the spatial distributions of pollen that they produce have typically been made among morphologically disparate pairs of species. In contrast, we investigated the potential extent of pollen dispersal by honey-bees (Apis mellifera) and bumble-bees (Bombus lapidarius, B. pascuorum and B. terrestris) foraging in rows of oil-seed rape (Brassica napus cv Westar).
  2. We estimated the pollen carryover attributable to individual bees by using particulate fluorescent dye as a pollen analogue. Most of the dye was deposited at the first few flowers probed and smaller proportions were deposited up to the 20th successively probed flower. We found no significant interspecific differences in dye carryover mediated by individuals of A. mellifera, B. lapidarius and B. terrestris with respect to either the amount deposited or the rate of decline in deposition across successively probed flowers. We present evidence that the dye produced a reasonably good analogue of pollen transfer.
  3. Bees typically flew from one plant to another nearby in the same row and were strongly directional in their movements. Bee species differed significantly in their movement patterns, with B. terrestris having the greatest mean move length and directionality.
  4. We used three kinds of model (a numerical simulation and two different sets of diffusion-advection equations) to attempt to emulate bee movements. The predictions from all models were reasonably consistent with the observed bee movements, although the numerical simulation invariably made the most accurate predictions, particularly over the first few moves.
  5. Predicted bee movements were combined with least-squares models of dye deposition to estimate the spatial dispersal of pollen by each bee species. All models ranked the bees in the same order of decreasing effectiveness in dye dispersal: B. terrestris, A. mellifera, B. lapidarius, B. pascuorum, although, except for long-distance dispersal, there was only minor variation among the bee species in the predicted extents of dye dispersal (e.g. the models predicted that the median dispersal distance would be approximately two intervening plants irrespective of the species of bee). Overall, the consensus of the models' predictions is that most of the pollen from a source plant is deposited on immediate neighbours, but that long-distance pollen dispersal in this system extends over approximately 20-40 intervening plants from the originating plant, depending on the identity of the pollinator.

History

Publication title

Functional Ecology

Volume

9

Issue

6

Pagination

829-841

ISSN

0269-8463

Department/School

School of Natural Sciences

Publisher

Blackwell Publishing Ltd

Place of publication

9600 Garsington Rd, Oxford, England, Oxon, Ox4 2Dg

Rights statement

Copyright 1995 British Ecological Society

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the biological sciences

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