Protective covers are commonly employed in agricultural systems to reduce the impacts of extreme weather events, pest species and to control the environmental conditions in which crop plants are grown. As protected cropping systems are expanding rapidly, there is an urgent need to better understand how variations in netting practices might impact pollination service delivery by wild and managed insects to pollinator dependent crops. We used southern highbush blueberry (Vaccinium corymbosum L. interspecific hybrid) crops to investigate (i) how variations in protected cropping structures (fully netted, partially netted and unnetted blocks) influence the amount and composition of pollen deposited on crop stigmas; (ii) to what extent blueberry floral abundance and plant richness in remnant vegetation influence pollen composition on crop stigmas; and (iii) the difference between stigmatic pollen load composition in the middle and at the edge of crop blocks. We collected data from 15 field blocks of 6 different cultivars distributed on 10 farms. We collected blueberry stigmas to analyse the pollen load and measured blueberry floral abundance and richness of flowering plant taxa in remnant vegetation every two weeks. Our results indicate that blueberry pollen abundance on stigmas was reduced by up to 81% under full netting and 36% by partial netting. On blueberry stigmas, we identified a total of 31 morphospecies of non-blueberry pollen from 20 plant families. There was no relationship between blueberry stigmatic pollen loads and blueberry floral abundance. Moreover, the composition of non-blueberry pollen on stigmas differed between blueberry blocks under different netting categories. However, there was no relationship between plant taxa present in the surrounding remnant vegetation of each block and the pollen load on the stigmas of each block. Combining all netting treatments, stigmas located at the edge of the blocks received a greater amount of both conspecific (5% more) and heterospecific (40% more) pollen grains than those within the middle of blocks. Pollen flow in fields is reduced under netting structures as well as in the middle of blocks. Reduced blueberry pollen flow under nets may be detrimental to fruit yield and quality for some varieties of pollinator dependent crops, particularly those that are self-incompatible.

保护性覆盖物通常用于农业系统，以减少极端天气事件、害虫物种的影响，并控制农作物生长的环境条件。随着受保护的种植系统迅速扩大，迫切需要更好地了解网状做法的变化如何影响野生和管理昆虫向依赖授粉媒介的作物提供授粉服务。我们使用南方高丛蓝莓 ( Vaccinium corymbosumL. 种间杂交）作物以研究（i）受保护的作物结构（完全网状、部分网状和未网状块）的变化如何影响沉积在作物柱头上的花粉的数量和组成；(ii) 蓝莓花的丰富度和残余植被中的植物丰富度在多大程度上影响作物柱头上的花粉组成；(iii) 作物块中间和边缘的柱头花粉量组成之间的差异。我们从分布在 10 个农场的 6 个不同品种的 15 个田块中收集了数据。我们每两周收集蓝莓柱头来分析花粉量，并测量蓝莓花的丰度和残余植被中开花植物类群的丰富度。我们的结果表明，蓝莓柱头上的花粉丰度在完全网播下减少了 81%，在部分网播下减少了 36%。在蓝莓柱头上，我们共鉴定出来自 20 个植物科的 31 种非蓝莓花粉形态。蓝莓柱头花粉量与蓝莓花丰度之间没有关系。此外，在不同网络类别下的蓝莓块之间，柱头上非蓝莓花粉的组成也不同。然而，每个区块周围残余植被中存在的植物类群与每个区块柱头上的花粉量之间没有关系。结合所有的结网处理，位于块边缘的柱头比块中间的柱头接收到更多的同种（多 5%）和异种（多 40%）花粉粒。在网状结构下以及在街区中间，花粉在田间的流动减少了。网下蓝莓花粉流量减少可能不利于某些依赖授粉媒介的作物品种的果实产量和质量，尤其是那些自交不亲和的作物。