Pollen transport differs among bees and flies in a human-modified landscape

Authors

  • Romina Rader,

    Corresponding author
    1. School of Marine and Tropical Biology, James Cook University, PO Box 6811, Cairns 4870, Qld, Australia
    2. The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, New Zealand
    • Romina Rader, School of Marine and Tropical Biology, James Cook University, PO Box 6811 Cairns 4870, Qld, Australia.
      E-mail: RominaRader@gmail.com

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  • Will Edwards,

    1. School of Marine and Tropical Biology, James Cook University, PO Box 6811, Cairns 4870, Qld, Australia
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  • David A. Westcott,

    1. School of Marine and Tropical Biology, James Cook University, PO Box 6811, Cairns 4870, Qld, Australia
    2. CSIRO Ecosystem Sciences, PO Box 780, Atherton, Qld 4883, Australia
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  • Saul A. Cunningham,

    1. CSIRO Ecosystem Sciences, Box 1700, Canberra, ACT 2601, Australia
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  • Bradley G. Howlett

    1. The New Zealand Institute for Plant and Food Research Limited, Private Bag 4704, Christchurch, New Zealand
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Abstract

Aim  Dispersal distances of insect pollinators are critical in defining their contribution to landscape-wide pollen movement and ultimately gene flow in natural and agricultural systems. We ask whether bee and fly pollinator taxa differ in their dispersal distances and transport of viable pollen in a human-modified system.

Location  Canterbury and Otago region, South Island, New Zealand.

Methods  We captured pollen-carrying insects travelling outside of a model mass-flowering agricultural crop, Brassica rapa, using insect flight intercept traps at five distances (0, 100, 200, 300 and 400 m) from the pollen source. We examined pollen loads and pollen viability to determine whether pollen transport distance and viability differ among pollinator taxa.

Results  A total of 5453 insects were collected of which 717 individuals from 26 insect taxa were positively identified as dispersing pollen up to 400 m from the source. These taxa consisted of four species from two bee families (Hymenoptera: Apidae and Halictidae), and eight species from four fly families (Diptera: Bibiondae, Stratiomyidae, Syrphidae and Tachinidae). Apidae generally carried higher pollen loads and more viable pollen than most fly taxa. Taxa in the fly families Stratiomyidae and Syrphidae, however, carried pollen to 400 m, which is further than both bee families.

Main conclusions  A diverse array of wild and managed flower visitors can transport viable pollen from a pollen source to at least 400 m. Knowledge of the differences in transport distances among generalist pollinators in human-modified environments is crucial to understand the potential extent to which (1) pollen transport can facilitate gene flow and (2) unwanted hybridization may occur between crops and related weeds.

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