Crowther, Lucy
(2019)
1. The effect of agri-environment schemes on bees on Shropshire farms. 2. The effect of agri-environment schemes on bumblebee colony success.
MRes thesis, University of Nottingham.
Abstract
The decline of bees and other invertebrate pollinators is cause for global concern, endangering the stability of ecosystems and economic markets. Modern intensive agriculture has been identified as a key driver causing this decline, through the loss of foraging and nesting habitats and agrochemical applications. Alterations to land management techniques and farming styles through Government-run agri-environment schemes (AES) have the potential to restore the local landscape to benefit wild bees. Bee abundance and species richness were surveyed over a season, along with forage plant usage, on 18 farms in Shropshire (UK) to assess the effectiveness of AES in conserving and restoring local bee communities. Farms were classified into three treatment groups: (i) Conventional (intensive farming with little to no input into “wildlife-friendly” farming actions), (ii) Entry-Level Stewardship AES (ELS: broad, flexible, non-competitive admission), and (iii) Higher-Level Stewardship AES (HLS: strict, high-input options, competitive admission), covering a range of farm types. Bee abundance and species diversity were significantly higher on AES-compliant farms when compared to Conventional farms. AES-compliant farms also showed greater flowering plant diversity used as foraging resources. Small non-significant differences in abundance and species richness were identified between ELS and HLS, with ELS slightly higher in mean species diversity and HLS slightly higher in overall abundance. This study highlights that set-aside of uncultivated field margins, hedgerow restoration, late-cut meadows and the sowing of nectar-rich flower mixes are effective AES options to improve the agricultural landscape for bee communities. Flowering plants currently considered agricultural weeds are important forage resources for bees throughout the season and can benefit local bee communities.
As with other species linked to agricultural environments, bumblebees are exhibiting significant population declines. The key drivers of this decline are habitat loss and fragmentation and application of agrochemicals, both resulting in a lack of foraging resources. With Apis mellifera unable to fulfil the current demand for crop pollination services, the services provided by domesticated and wild bumblebees are gaining importance. This study assesses the ability of Bombus terrestris audax (a species used for commercial crop pollination) colonies to be successful in agricultural ecosystems and compares whether current agri-environment schemes can increase colony success. Artificial nest boxes, containing B. terrestris audax colonies were places out in farmland, either conventionally managed or compliant with Entry-Level Stewardship (ELS) or Higher-Level Stewardship (HLS) agri-environment schemes (AES). Monitoring of colony growth rates through total nest box weight showed that colonies on AES-compliant farms gained significantly more weight than those on conventional farms, with nest boxes on conventional farms showing weight loss. Nests located on conventional farms were also more likely to become infested by the parasite Aphomia sociella, followed by ELS-compliant farms. The results of this study suggest that current AES have the potential to increase the likelihood of B. terrestris audax colony success, through the production of larger colonies, with greater ability to combat parasites infestations. Land management under AES generated ecosystems with greater floral diversity, more mid-succession habitats, and connectivity between these habitats, significantly benefiting bumblebee colony success.
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