[ExI] bees

[Anders Sandberg]

Just came across this paper, which is mildly hopeful in the sense that 
there is a backup for many (but not all) plants:

Non-bee insects are important contributors to global crop pollination
http://www.pnas.org/content/early/2015/11/24/1517092112.full.pdf
http://www.pnas.org/content/early/2015/11/24/1517092112.abstract
> Wild and managed bees are well documented as effective pollinators of 
> global crops of economic importance. However, the contributions by 
> pollinators other than bees have been little explored despite their 
> potential to contribute to crop production and stability in the face 
> of environmental change. Non-bee pollinators include flies, beetles, 
> moths, butterflies, wasps, ants, birds, and bats, among others. Here 
> we focus on non-bee insects and synthesize 39 field studies from five 
> continents that directly measured the crop pollination services 
> provided by non-bees, honey bees, and other bees to compare the 
> relative contributions of these taxa. Non-bees performed 25–50% of the 
> total number of flower visits. Although non-bees were less effective 
> pollinators than bees per flower visit, they made more visits; thus 
> these two factors compensated for each other, resulting in pollination 
> services rendered by non-bees that were similar to those provided by 
> bees. In the subset of studies that measured fruit set, fruit set 
> increased with non-bee insect visits independently of bee visitation 
> rates, indicating that non-bee insects provide a unique benefit that 
> is not provided by bees. We also show that non-bee insects are not as 
> reliant as bees on the presence of remnant natural or seminatural 
> habitat in the surrounding landscape. These results strongly suggest 
> that non-bee insect pollinators play a significant role in global crop 
> production and respond differently than bees to landscape structure, 
> probably making their crop pollination services more robust to changes 
> in land use. Non-bee insects provide a valuable service and provide 
> potential insurance against bee population declines. 

>
>     Significance
>
> Many of the world’s crops are pollinated by insects, and bees are 
> often assumed to be the most important pollinators. To our knowledge, 
> our study is the first quantitative evaluation of the relative 
> contribution of non-bee pollinators to global pollinator-dependent 
> crops. Across 39 studies we show that insects other than bees are 
> efficient pollinators providing 39% of visits to crop flowers. A shift 
> in perspective from a bee-only focus is needed for assessments of crop 
> pollinator biodiversity and the economic value of pollination. These 
> studies should also consider the services provided by other types of 
> insects, such as flies, wasps, beetles, and butterflies—important 
> pollinators that are currently overlooked.
>

-- 
Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University

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