Contribution of insect pollinators to crop yield and quality varies with agricultural intensification

Abstract

Background. Up to 75% of crop species benefit at least to some degree from animal pollination for fruit or seed set and yield. However, basic information on the level of pollinator dependence and pollinator contribution to yield is lacking for many crops. Even less is known about how insect pollination affects crop quality. Given that habitat loss and agricultural intensification are known to decrease pollinator richness and abundance, there is a need to assess the consequences for different components of crop production.Methods. We used pollination exclusion on flowers or inflorescences on a whole plant basis to assess the contribution of insect pollination to crop yield and quality in four flowering crops (spring oilseed rape, field bean, strawberry, and buckwheat) located in four regions of Europe. For each crop, we recorded abundance and species richness of flower visiting insects in ten fields located along a gradient from simple to heterogeneous landscapes.Results. Insect pollination enhanced average crop yield between 18 and 71% depending on the crop. Yield quality was also enhanced in most crops. For instance, oilseed rape had higher oil and lower chlorophyll contents when adequately pollinated, the proportion of empty seeds decreased in buckwheat, and strawberries’ commercial grade improved; however, we did not find higher nitrogen content in open pollinated field beans. Complex landscapes had a higher overall species richness of wild pollinators across crops, but visitation rates were only higher in complex landscapes for some crops. On the contrary, the overall yield was consistently enhanced by higher visitation rates, but not by higher pollinator richness.Discussion. For the four crops in this study, there is clear benefit delivered by pollinators on yield quantity and/or quality, but it is not maximized under current agricultural intensification. Honeybees, the most abundant pollinator, might partially compensate the loss of wild pollinators in some areas, but our results suggest the need of landscape-scale actions to enhance wild pollinator populations.

Comparison of buckwheat, red clover, and purple tansy as potential surrogate plants for use in semi-field pesticide risk assessments withBombus impatiens

“…common), red clover ( Trifolium pratense ), and purple tansy ( Phacelia tanacetifolia ) as potential surrogate plants for semi-field pesticide studies with the common eastern bumble bee ( Bombus impatiens Cresson). We focussed on these plants because they are attractive to bumble bees (Williams, 1997; Carreck & Williams, 2002; Pontin et al, 2006; Jacquemart, Gillet & Cawoy, 2007; Colla & Dumesh, 2010; Bartomeus et al, 2014), and purple tansy has previously been used in semi-field studies with bees (Cabrera et al, 2016). Bombus impatiens is abundant throughout eastern Canada and United States, and currently is the only bumble bee available commercially for crop pollination in North America.…”

Functional identity and diversity of animals predict ecosystem functioning better than species-based indices

“…We analysed three separate datasets conducted in three crop systems (field beans, strawberries and spring oilseed rape) in UK, Germany and Sweden, respectively [26]. Bees were sampled in 10 fields in each crop type by hand-netting along a fixed transect.…”

Pollination services mapping and economic valuation from insect communities: a case study in the Azores (Terceira Island)

“…cabbage and other brassicas, carrots, turnips, lettuce, chicory and onions) increases the quality of the seed production (Gallai and Vassière 2009). In addition, insect pollinators enhance fruit and seed quality Bartomeus et al 2014;Garratt et al 2014;Marini et al 2015;Saeed et al 2016) and reinforces pest management (Cross et al 2015) which constitutes an indirect and difficult benefit to measure, but extremely important for the agricultural market. Also, a recent study on pollination by wild insect pollinators has showed their capacity to increase the seed production in 41 agricultural systems globally, regardless of the abundance of honey bees .…”