Proximity to natural habitat and flower plantings increases insect populations and pollination services in South African apple orchards

Fabrizia Ratto,William Kunin,Steven M Sait,Peter Steward,Rene Gaigher,James Stephen Pryke,Michael J Samways

doi:10.1111/1365-2664.13984

Fabrizia Ratto, William Kunin + Show 5 more

Open Access

https://doi.org/10.1111/1365-2664.13984

Copy DOI

Abstract

Abstract Introducing areas of wildflower vegetation within crop fields has been shown to enhance pollinator activity and pollination services to crops, and findings in Europe showed an interaction effect between floral treatments and landscape context. Natural fynbos patches in the South African Cape Floristic Region (CFR) are potential reservoirs for beneficial insects that could enhance pollinator populations and crop pollination in commercial apple orchards. However, the effect of proximity to natural habitat and floral enhancement treatments on crop pollinators and yield are yet to be fully tested in southern temperate regions. To elucidate the impact of enhanced floral resources to apple flower visitors and crop yield, we established small experimental patches of flowers in non‐productive areas of commercial apple Malus domestica orchards in the CFR. Experimental orchards were embedded in landscapes with varying proportions of natural habitat within 1 km. We used pollinator exclusion experiments to determine the benefits of insect pollination on apple yield, quality and economic value. We found that the primary pollinator of apple flowers in the region is the endemic Cape honey bee, Apis mellifera capensis. Floral plantings enhanced overall pollinator abundance and honey bee flower visitation within the orchards, and positively affected apple size and economic value. Increased landscape complexity had a significantly positive effect on wild bees but not on honey bees. Synthesis and applications. We demonstrate that presence of floral plantings within orchards enhances pollinator activity within apple orchards and apple quality. This sustainable management practice may represent a profitable choice for growers, which could increase pollination services while reducing reliance on renting hives. These practices can indirectly contribute to increased landscape‐scale resilience and connectivity while also benefiting pollinators within the remaining natural habitat.

Highlights

Animal pollination is required for most of the world's flowering plants (Ollerton et al, 2011) and plays a key role in agroecosystems worldwide, where it enhances yield of many crops (Klein et al, 2007)
We found that the primary pollinator of apple flowers in the region is the endemic Cape honey bee, Apis mellifera capensis
This is the first study to quantify the impact of floral enhancement on apple orchard insects and on both yield and quality of this economically important crop in South Africa

Summary

| INTRODUCTION

Animal pollination is required for most of the world's flowering plants (Ollerton et al, 2011) and plays a key role in agroecosystems worldwide, where it enhances yield of many crops (Klein et al, 2007). Growing evidence suggests that integrating floral resources into farms increases both abundance of wild insects and the services they provide (Blaauw & Isaacs, 2014; Tscharntke et al, 2012). This is usually achieved by sowing mixes of native grassland flower species on arable land (Carvell et al, 2004), and, in Europe, it forms part of Agri-Environment Schemes (Pywell et al, 2006). We hypothesise that flower visitor abundance, fruit yield and quality measures, and economic value would increase in apple trees adjacent to floral plantings, and that these benefits would be greater in orchards surrounded by simple landscapes

| MATERIALS AND METHODS

Position of experimental tree

Findings

| DISCUSSION