Influence of Wild Bee Diversity on Canola Crop Yields

Rosana Halinski,Charles Fernando Dos Santos,Tatiana Guterres Kaehler,Betina Blochtein

doi:10.13102/sociobiology.v65i4.3467

Abstract

The foraging range of bees determines the spatial scale over which each species can provide pollination services. In agricultural ecosystems, productivity is related not only to the taxonomic diversity of bees per se, but also to the location of their nesting sites, which reflects on their flying range. Within this context, the present study sought to assess how wild bee assemblages affect the yield of Brassica napus at three different distances (25 m, 175 m, 325 m) from forest remnants in Southern Brazil. Bees were sampled by means of pan traps and findings were analyzed using the Shannon diversity index and generalized linear models. We identified 11 species of native bees, both solitary and social, as well as the exotic species Apis mellifera, which was most abundant. Our findings show that canola crop yield were positively influenced by the diversity of bee species. This demonstrates that native bees, not only A. mellifera, can contribute significantly to the productivity of canola crops. In addition, we found that bee body size is significantly associated with flight distance traveled within the canola fields, and demonstrated a relationship with nesting sites. Thus, we hypothesize that canola yields are associated with the presence of wild bee species, both social and solitary, and that maintenance of these pollinators is directly dependent on practices adopted in rural areas, whether within plantation fields per se or in forest remnants used as nesting sites by wild bees.

Highlights

Pollinators play an important functional role within ecosystems by providing environmental services essential to the reproduction and survival of plants (Potts et al, 2016)
Despite the apparent predominant role of A. mellifera bees in the canola fields, native bee species warrant attention, whether because some of them were present in all distances or because their behavior makes them as efficient as A. mellifera for pollination of this crop
This is an interesting finding because, T. spinipes is smaller than A. mellifera

Summary

Introduction

Pollinators play an important functional role within ecosystems by providing environmental services essential to the reproduction and survival of plants (Potts et al, 2016). A full 33% of plants grown for human consumption is known to depend on beemediated cross-pollination (Klein et al, 2007). This beneficial relationship between bees and plants can be threatened in several ways. Pollinator populations are subject to various effects of forest fragmentation, including agriculture, animal husbandry, and other anthropogenic pressures (Cresswell & Osborne, 2004). This gradual reduction of natural landscapes significantly reduces the flow of animals, pollen, and seeds (Samways, 1995). Habitat fragmentation may have negative impacts on richness and diversity of several functional groups, including pollinator insects (Kremen et al, 1993)

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Conclusion