Non-bee insects are important contributors to global crop pollination

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.unmanaged pollinator | insect pollinator | fly | bee | beetle

Insights from measuring pollen deposition: quantifying the pre-eminence of bees as flower visitors and effective pollinators

“…Even fewer plants were well-served by butterflies and moths, with much more occasional deposition efficiency from wasps or muscid flies, whilst beetles and ants were largely ineffective. And although 'bees are usually best', and wild bees often better than honeybees, it is also crucially important to recognise that non-bee insects can be vital to particular cases of global crop pollination, as most recently highlighted by Rader et al (2016), and for some more specialised angiosperms (e.g. those that are vertebratepollinated) in other ecosystems.…”

Experimental evidence that honeybees depress wild insect densities in a flowering crop

“…In many parts of the world, wild bee populations have declined, mainly due to habitat degradation and loss caused by land-use conversion, pesticide use, pathogens, and loss of pollen-and nectar-producing flower resources [3], posing a threat to crops dependent on insect pollination [4]. Wild flower-visiting insects other than bees also provide crop pollination [5], but less is known about the factors affecting their densities [3]. Adding managed honeybees to mass-flowering crops is a widespread practice for bolstering pollination, sometimes used to compensate for insufficient numbers of wild pollinators [6], and to produce honey [7].…”

Pollinators and Global Food Security: the Need for Holistic Global Stewardship

“…Globally, over 25,000 species of bees are known (Chagnon et al 2015). However, many insects other than bees are also efficient pollinators, providing 39 % of visits to crop flowers (Rader et al 2015). Wild insect pollinator species are regarded as the most effective pollinators of fruit crops (Chagnon et al 2015).…”