Pollination by wild bees yields larger strawberries than pollination by honey bees

Abstract

A diverse array of wild bee species may provide more effective pollination than the widely employed European honey bee (Apis mellifera L.). High species richness within crop pollinator assemblages has been linked to enhanced fruit and seed yields, but species richness is often confounded with abundance in studies of pollinator communities. We investigated the effects of bee diversity and species identity on pollen deposition and crop yield in the strawberry (Fragaria × ananassa) variety Jewel through a field experiment that independently manipulated the species richness and abundance of flower visitors. We used a new pollen deposition measurement technique to determine the pollen contribution of individual bees in an assemblage of flower visits. We compared the performance of wild bee species and managed honey bees, as pollinators of strawberry. We also calculated the influence of species richness, visit frequency and visitor identity on fruit mass, using the fruit that developed from each sampled flower. Species richness of flower visitors did not influence floral pollen loads or strawberry mass. Honey bees and wild bees deposited the same amount of pollen per visited flower. However, strawberries that developed from flowers visited by wild bees were heavier than flowers visited by honey bees. In addition, flowers visited by a combination of wild and honey bees produced strawberries that weighed less than flowers receiving purely WB visits. Synthesis and applications. Our findings show that honey bee pollination results in lower yields than wild bee pollination in a strawberry crop. Consequently, if managed honey bees in strawberry fields displace wild pollinators, growers may obtain suboptimal yields. Management efforts aimed at the maintenance or enhancement of wild pollinator populations may therefore be a cost‐effective way to increase both crop yield and biodiversity on strawberry farms.

The economic cost of losing native pollinator species for orchard production

“…The most common management practice used to increase yield of pollinator‐dependent crops consists in adding high amounts of honeybees (Aebi et al, ; Goodwin et al, ; Rucker et al, ). However, recent evidence shows that honeybees, even when present at high abundances, are not able to close yield gaps when other wild pollinators that complement crop pollination are not present (Garibaldi et al, ; MacInnis & Forrest, ). Fruit set of apples was reduced by more than half in farms with high densities of honeybees but lacking native bumblebees compared to farms with both pollinator groups.…”

“…Harder, Aizen, & Richards, ). Moreover, because honeybees are not necessarily efficient pollinators of some crops or crop production may depend on different pollinator species, it is not expected that honeybees by themselves are able to maximize crop yield (Garibaldi et al, , ; Grass et al, ; MacInnis & Forrest, ).…”

“…This bumblebee species has been identified as an efficient pollinator of different crops such as tomatoes, strawberries and peppers amongst others (Aldana, Cure, Almanza, Vecil, & Rodríguez, ; Poveda‐Coronel, Riaño Jiménez, Aguilar Benavides, & Cure, ; Riaño, Pacateque, Cure, & Rodríguez, ), and has been reported as a floral visitor in apples (Abrahamovich, Tellería, & Díaz, ). Whereas many studies have focused on the relationship between honeybee density or pollinator diversity and crop production (Garibaldi et al, , ; Geslin, Aizen, et al, ; MacInnis & Forrest, ; Sáez et al, ), only a few have assessed the individual contribution of key native pollinator species in crop production. Furthermore, as far as we know, no study has evaluated the effect on production and economic cost for local farmers of losing a particular pollinator species such as the black bumblebee.…”

Citizen science improves our understanding of the impact of soil management on wild pollinator abundance in agroecosystems

“…As a result, researchers are investigating the role of wild bees as crop pollinators, which are declining due to human disturbances such as habitat loss/fragmentation [6], landscape simplification [7], and increased pesticide use [8]. Management practices that increase abundance and species richness of native bees can ameliorate crop pollination deficiencies [9], especially for crops that are more effectively pollinated by native bees [10][11][12][13][14][15].…”

Varietal and seasonal differences in the effects of commercial bumblebees on fruit quality in strawberry crops

“…Strawberry ( Fragaria x ananassa DUCH) is a major soft fruit crop, worth £284 million in the UK in 2015 (DEFRA, 2015). Several bee species, both managed and wild, have been shown to be effective pollinators of strawberry (Connelly et al, 2015; Dimou et al, 2008; Klatt et al, 2014; MacInnis and Forrest, 2019). The proportion of the strawberry pollinator community that is made up of bumblebees varies.…”