Proximity to Woodland and Landscape Structure Drives Pollinator Visitation in Apple Orchard Ecosystem

Neelendra K Joshi,Mark Otieno,Edwin G Rajotte,Shelby J Fleischer,David J Biddinger

doi:10.3389/fevo.2016.00038

Abstract

Landscapes of farms and adjacent areas are known to influence abundance of various arthropods such as pollinators in commercial agricultural ecosystems. In this context, we examined the effect of heterogeneous landscapes surrounding and including commercial apple orchards on pollinator visitation and foraging distance during bloom period from 2011 to 2013 in Pennsylvania. Our results showed that the frequency of feral honeybees and solitary bee visits within an apple orchard depends on the proximity of the orchard to an unmanaged habitat (primarily comprised of forest). At the landscape scale, we found that the Mean Proximity Index, the Largest Patch Index and the Number of Patches positively correlated with the visitation rate of dominant bee taxa (Apis mellifera, Bombus spp. and solitary bees) visiting apple flowers at low spatial scales (up to 500 m around the orchards). The Mean Proximity Index at 500 m was related to bee visitation patterns, especially for solitary bees and A. mellifera. Bees in all our study sites preferred to forage in areas with large homogenous patches up to 500 m around an apple orchard. This effect can be attributed to the mass flowering of apples that formed the largest proportion of the 500 m spatial scale. The Number of Patches at 250 m spatial scale was positively correlated with bee visitation, especially Bombus spp., probably because these areas had more habitats and more resources required by these bees. We conclude that retaining unmanaged habitats closer to commercial apple orchards will maintain biodiversity within the landscapes and insure pollination services to apples.

Highlights

Agricultural crop production relies heavily on insects to provide pollination services (Zhang et al, 2007; Potts et al, 2010)
During the last few years, population decline in honey bees and other wild bees like bumble bees have been reported in North America and Europe (Grixti et al, 2009; Cameron et al, 2011), similar trends have not been documented in other parts of the world such as Australia and Africa
Our study showed that the distance of apple orchards from surrounding heterogeneous landscape has significant effects on the foraging activity of bees that provide an important ecosystem service during bloom period

Summary

Introduction

Agricultural crop production relies heavily on insects to provide pollination services (Zhang et al, 2007; Potts et al, 2010). Among several species of insects, managed bees, mainly honey bees (Apis mellifera), and bumble bees (Bombus spp.), commonly make up for shortages in wild pollinators and feral honey bees that provide pollination services in various crops (Potts et al, 2010). Preserving natural and semi-natural habitats surrounding farmlands under commercial crop production may provide nesting and forage resources and buffer pollinators from adverse conditions. Such natural resource management strategy may increase the amounts of ecosystem services provided by pollinators, resulting in increased crop yields, and quality of produce (Holzschuh et al, 2012)

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Results

Conclusion