The importance of multi‐year studies and commercial yield metrics in measuring pollinator dependence ratios: A case study in UK raspberries Rubus idaeus L
The benefit of pollinators to crop production is normally calculated using “pollinator dependence ratios,” which reflect the proportion of yield lost (here reported as a value between 0 and 1) in the absence of pollinators; these ratios are quantified experimentally using pollinator exclusion experi...
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| Published in: | Ecology and evolution Vol. 13; no. 5; pp. e10044 - n/a |
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| Main Authors: | , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
England
John Wiley & Sons, Inc
01-05-2023
John Wiley and Sons Inc Wiley |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The benefit of pollinators to crop production is normally calculated using “pollinator dependence ratios,” which reflect the proportion of yield lost (here reported as a value between 0 and 1) in the absence of pollinators; these ratios are quantified experimentally using pollinator exclusion experiments. Pollinator dependence ratio estimates can vary considerably for a single crop, creating large, frequently overlooked, uncertainty in economic valuations of pollinators. The source of this variation is usually unclear. We experimentally measured the pollinator dependence ratio of two UK commercial cultivars of raspberry Rubus idaeus L., using a range of yield metrics—fruit set, marketable fruit set, fruit weight, and marketable fruit weight—over 3 years (2019–2021), to quantify the effects of yield metric, interannual variation, and cultivar on pollinator dependence ratio estimates. We found a difference in the pollinator dependence ratio for fruit set of 0.71 between 2019 and 2020, showing the importance of carrying out exclusion studies over multiple years. Averaged over multiple years and two cultivars, the dependence ratio was 0.68 measured using marketable fruit set and 0.64 using marketable fruit weight. Imposing a quality threshold (size and shape) below which fruits would not be of commercial value (marketable fruit set/weight) dramatically increased both the pollinator dependence ratio and subsequent economic valuations of pollination service derived from it. Our study shows that, for raspberry, estimates of the pollinator dependence ratio, and therefore, the economic value of insect pollinators, are highly sensitive to the choice of yield metric and can change between years and cultivars. Many economic decisions about pollinator management, at farm, regional and national scales rely on estimates of pollinator dependence. We, therefore, recommend that for estimating pollinator dependence ratios, pollinator exclusion studies are conducted over three or more years and use yield metrics that incorporate quality criteria linked to actual market values and commercial thresholds.
Pollinator dependence ratios are important for quantifying the benefit of pollinators to crops. Pollinator dependence ratios often are not calculated using commercially relevant yield metrics and are frequently informed by single‐year studies. We show that the pollinator dependence on raspberry varied greatly between years and with differing yield metrics. Imposing a threshold fruit quality (size and shape) below which fruits would not be of commercial value (marketable fruit set) dramatically increased both the pollinator dependence ratio and subsequent economic valuations of pollination service derived from it. Our results show the influence of yield metrics on pollinator dependence estimates and the economic value of pollinators, and we recommend that pollinator exclusion studies are conducted over multiple years (three or more) and use yield metrics that incorporate quality criteria linked to actual market values and commercial thresholds of the product in question. |
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| Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 2045-7758 2045-7758 |
| DOI: | 10.1002/ece3.10044 |