Pollination deficits and their relation with insect pollinator visitation are cultivar-dependent in an entomophilous crop

Insects contribute considerably to global crop pollination, with pollination deficits being documented for multiple entomophilous or pollinator-dependent crops. Different cultivars of crops are being cultivated within and across production regions, so it is essential to understand the cultivar variability of pollination deficits. Here, we used a dataset from 286 sites from multiple production regions to develop a synthesis on pollination deficits in two widely cultivated highbush blueberry cultivars, ‘Bluecrop’ and ‘Duke’. Additionally, we determined if bee visitation or bee richness reduces pollination deficits in these cultivars. On average, neither cultivar showed pollination deficits regarding fruit set. However, for ‘Bluecrop’ we found pollination deficits for berry weight and seed set, which was not the case for ‘Duke’. Increasing total bee visitation reduced pollination deficits of both berry weight and seed set for ‘Bluecrop’. More specifically, a non-linear, negative exponential model best predicted this relation between bee visitation and pollination deficits. Our results highlight that pollination deficits and responses to pollinator visitation are variable between different cultivars of a single crop, which suggests opportunities to use certain cultivars that are less dependent on insect-mediated pollination in landscapes and regions where pollination services have been compromised. In addition, the non-linear response between bee visitation and pollination deficits suggests that optimal bee visitation rates need to be determined to improve pollination management and crop yield and to support accurate economic valuations of pollination services.昆虫对全球作物授粉贡献显著，已有研究证实多种虫媒授粉（entomophilous）或依赖传粉者的作物（pollinator-dependent crops）存在授粉不足（pollination deficits）问题。不同作物品种在各生产区域内外广泛种植，因此探究授粉不足的品种间差异至关重要。本研究利用来自多个生产区域的286个样地数据集，对两个广泛栽培的高丛蓝莓品种‘Bluecrop’与‘Duke’的授粉不足情况开展综合分析。此外，本研究还探究了蜜蜂访花频次（bee visitation）与蜜蜂物种丰富度（bee richness）是否可缓解这两个品种的授粉不足问题。平均而言，两个品种的坐果率（fruit set）均未出现授粉不足情况。但针对‘Bluecrop’，研究发现其浆果重量（berry weight）与结籽量（seed set）存在授粉不足问题，而‘Duke’则无此现象。总蜜蜂访花频次的提升可缓解‘Bluecrop’的浆果重量与结籽量相关的授粉不足问题。具体而言，非线性负指数模型（non-linear, negative exponential model）最能拟合蜜蜂访花频次与授粉不足之间的关联。本研究结果表明，同一作物的不同品种间，授粉不足情况以及对传粉者访花的响应均存在差异，这意味着在授粉服务受损的景观与区域中，可选择对昆虫介导授粉（insect-mediated pollination）依赖度更低的品种进行种植。此外，蜜蜂访花频次与授粉不足之间的非线性响应关系表明，需确定最优访花频次，以优化授粉管理、提升作物产量，并为授粉服务的精准经济估值提供支撑。